Zootaxa 4422 (4): 451–477 http://www.mapress.com/j/zt/ ISSN 1175-5326 (print edition) Article Copyright © 2018 Magnolia Press ZOOTAXA ISSN 1175-5334 (online edition) https://doi.org/10.11646/zootaxa.4422.4.1 http://zoobank.org/urn:lsid:zoobank.org:pub:678C3281-5FAD-4BEA-B08A-2584E5897B4C A taxonomic revision of the genus Thalia Blumenbach, 1798; Weelia Yount, 1954; Brooksia Metcalf, 1918 (Salpida: Salpidae) from East Coast of Peninsular Malaysia NURUL HUDA BINTI AHMAD ISHAK1,2,4, NUR ‘ALIAH BINTI ADAM2 & ZALEHA KASSIM3 1 School of Marine and Environmental Sciences, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia Institute of Oceanography and Environment, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia 3 Marine Science and Technology Department, Kuliyyah of Science, International Islamic University Malaysia, 25200 Kuantan, Pahang, Malaysia 4 Corresponding author. E-mail: huda@umt.edu.my 2 Abstract The marine pelagic tunicates of Family Salpidae Lahille, 1888 presence in the coastal waters of Terengganu was studied for the first time. Samples were collected from April to July 2016 using 200µm Bongo net; hauled vertically from a stationary vessel; and preserved in 5% buffered formaldehyde. A total of 4 species under this family were found, observed and identified: Thalia rhomboides (Quoy and Gaimard 1824); Thalia sibogae (van Soest 1973); Weelia cylindrica (Cuvier 1804) and Brooksia rostrata (Traustedt 1893). All species were identified as new records in Malaysian waters. The description on morphological characteristics and a key to the solitary and aggregate of the recorded species is added. The distribution was analyzed from the 18 sampling stations in theTerengganu waters including Pulau Bidong, Pulau Yu and Pulau Kapas. The collected data was then compiled with previous available global literature on the distribution and occurrence of these four species, consequently updating the biodiversity of Malaysian fauna and its worldwide biogeography distribution. Key words: salp, pelagic tunicates, South China Sea, Terengganu Introduction Thaliaceans are conspicuous members of gelatinous zooplankton comprised of salps, doliolids and pyrosomes (Bone 1998). They are extremely diverse in morphology (Esnal & Daponte 1999; Sutherland 2010), life history (Alldredge & Madin 1982; Heron & Benham 1985; Verity & Smetacek 1996; Daponte et al. 2001; Lobón, et al. 2011; Deibel & Lowen 2012) and mode of reproduction (Purcell & Madin 1991; Daponte et al. 2013). The species are mostly distinguished by their shape and the numbers and arrangement of the muscle bands which encircle their bodies (Borgelt 1968; Esnal & Daponte 1999). Salps are pelagic tunicates which are widely distributed in all oceans (Van Soest, 1998) and the geographic ranges of most species are wide and distributed by the ocean currents (Van Soest 1973a, 1973b, 1974a, 1974b, 1975a, 1975b; Diaz, et al. 2008). In more recent years, there has been increased appreciation of the importance of gelatinous animals in the marine ecosystem (Esnal & Daponte 1999; Briand 2002). Salps are able to feed efficiently on phytoplankton and zooplankton, consuming particles from <1 µm to 1 mm in size (Acuna 2001; Vargas & Madin 2004), but they are also a slightly selective feeder (Ahmad Ishak et al. 2017). They transfer the carbon out of the euphotic zone through fast-sinking carbon-rich faecal pellets and carcasses (Henschke et al. 2013) and deposit them into the bottom of the ocean (Bruland & Silver 1981). Despite their significant ecological importance, there is a lack of data on their basic ecological traits and function in the ecosystem (Heron 1972; Harbison et al. 1986; Raskoff et al. 2003, Henschke et al. 2016), presumably because it has been a major challenge to obtain information on their ecologically-related variables. Ideally,it is because of their hardly predictable and intermittent occurrence in various parts of the oceans. Accepted by R. Brunetti: 9 Apr. 2018; published: 25 May 2018 451 Generally, salps are present in low abundances in relation to other zooplankton groups (Diaz et al. 2008) and they often occur in a patchy distribution in the water column (Alldredge & Madin 1982; Voronina 1998; Pakhomov & Hunt 2017). Moreover, they are particularly prone to damage both during capture and subsequent preservation process (Foxton 1965; Alldredge & Madin 1982; Sameoto 1984; Romeo et al. 1992; Menard et al. 1994; Nishikawa & Terazaki 1996; Weikert & Godeaux 2008; Liu et al. 2012; Hereu et al. 2014). At times when wellpreserved salps collection becomes almost impossible (Madin et al. 1996), it caused significant difficulties in identifying the species due to the tunic fragility (Diaz et al. 2008). The order Salpida contains 1 family with 2 subfamilies: Cyclosalpinae Yount, 1954 including 2 genera, and Salpinae Yount, 1954 with eleven genera. The Salpidae, one of the largest families of holoplanktonic tunicates with 48 species in 11 genera, have been described (Chihara and Murano 1997; Godeaux 1998; Esnal and Daponte 1999; Purushothaman et al. 2017). New discovered species are remarkably scanty (Hereu et al. 2014) with only one new species been added in 2000s (Garic and Batistic, 2016). While most extensive taxonomical studies of marine zooplankton in Malaysia are focused on group Crustacea (Copepoda), Cyanobacteria, eukaryotic algae, Protozoa, Platyhelminthes, Nematoda and Tunicata (Yasin et al. 2015), only limited information was available on Thaliacea. In fact, no records of taxonomical studies on salps in Malaysian waters are recorded. Most of our awareness on the presence of salps in Malaysia comes from very few studies (Hoeksema & Waheed 2012; Waheed & Hoeksema 2014; Mehrotra et al. 2016). Still, little is known on Thaliaceans general biology, ecology and distribution and this information is particularly scarce in this region. Therefore, it is the aim of this study to describe morphological characteristics to aid in identification of the species in Malaysian waters, to list the species diversity and to enlarge the distribution of the salps. A key for the identification of these salps species is also included with a basic set of morphological data. Materials and methods Study area. The South China Sea (SCS) lies in the tropical zone of the western Pacific Ocean. The southern SCS is bordered by Peninsular Malaysia in the west and Borneo in the East. The region in general is primarily subjected to the monsoon seasons (Chu et al. 1999). The northeast monsoon dominates the southern SCS region from November to March which results in strong northeasterly monsoon winds, while the southwest monsoon provides the region with southwesterly wind between April to August. The surveyed region is located along Terengganu coast facing to SCS. The physical properties and dynamical movements in Terengganu are influenced by SCS condition. Its coastal area is a shallow shelf area with water depth less than 80 m (Rabitah et al. 2016). This region experiences a relative dry season from April to July, while the heaviest precipitation in November and December which reaches more than 1,000 mm of rainfall (Camerlengo & Somchit 2000). The surface waters are relatively warm, 29 °C in the SW monsoon, because of the low latitude. Monsoon winds influence the equatorial current by moving the warm water into the region (Nicholson 2011; Thompson & Tkalich 2014). It is reported that during the northeast monsoon, temperature and salinity recorded are lower (Chua 1984; Zainal 1993; Saadon & Carmerlengom 1996). Sampling procedure. Four monthly samplings were conducted from April 2016 to July 2016 during the Southwest monsoon (warmer waters) at 18 sampling stations (Fig.1) around Terengganu Waters. Specimens were collected with a cylindrical-conical paired-Bongo net of mesh size 200 μm and mouth diameter of 60 cm, fitted with a calibrated flowmeter to determine the volume of filtered water during each tow (unit: m3). The net was hauled vertically from different depths (15–45 m) but always started at 5 m above the seafloor. The specimens collected were preserved immediately in 5% buffered formaldehyde diluted with seawater prior to identification and enumeration. Temperature and salinity were measured on board at each station using a HydroLab Quanta Multiparameter Water Quality probe. Laboratory procedure. In the laboratory, the zooplankton samples were sorted and all salps were separated. Salps were submerged for 24 hours in 2% Rose Bengal or Toluidine blue solution for better observation of the taxonomic characters and later observed under a stereoscopic and a compound microscope. Salps were identified to species level based on taxonomy references of Thompson (1948), Yount (1954), van Soest (1973 & 1975), Chihara & Murano (1997), Godeaux (1998), and Esnal and Daponte (1999). The specimens were identified by the characters their muscle bands, atrial palps, projections and the morphology of the specimen. Identified specimens 452 · Zootaxa 4422 (4) © 2018 Magnolia Press AHMAD ISHAK ET AL. were photographed using a digital camera mounted onto the stereo microscope. All the photographs are original, based on the collected material. Specimens examined in this study are deposited at the South China Sea Repository and Reference Center, Institute of Oceanography and Environment, Universiti Malaysia Terengganu (UMTTn), Kuala Nerus. FIGURE 1. Area and sampling stations in Terengganu waters. Results Description and distribution of Salpidae from East coast of Malay Peninsular 1. Thalia rhomboides Quoy & Gaimard, 1824 Salpa rhomboides Quoy & Gaimard, 1824 (cited from van Soest 1973; Kott 2005) Salpa pyramidalis sensu Quoy & Gaimard, 1834 (cited from van Soest 1973, Kott 2005) Salpa mucronata Apstein, 1906 (cited from Purushothaman 2017) Thalia democratica Sewell, 1926 Thalia democratica var. orientalis Tokioka, 1937 SALPS FROM THE EAST COAST OF PENINSULAR MALAYSIA Zootaxa 4422 (4) © 2018 Magnolia Press · 453 Thalia democratica var. orientalis f. echinata Tokioka, 1937 Thalia democratica echinate form Yount, 1954 Thalia democratica intermedia Borgelt, 1968 Thalia rhomboides van Soest, 1973: 199–200, 1998: 238 fig. 14.3, table 14.3; Godeaux, 1998: 288 fig. 17.17, 293 fig. 17.21; Chihara & Murano, 1997: 1384-1385; Kim, 2011: 147–148 Specimens examined. A2: 1 aggregate zooid, 5°39'55.02"N, 103° 0'6.03"E, April 2016; A3: 3 aggregate zooids, 5°40'51.01"N, 103° 1'51.06"E, April 2016; A6: 1 aggregate zooids, 5°39'50.59"N, 103° 9'36.64"E, April 2016; C1: 2 aggregate zooids, 5°20'47.59"N, 103° 8'59.91"E, Jun 2016; C2: 5 solitary zooids, 12 aggregate zooids, 5°25'33.93"N, 103°17'32.72"E, Jun 2016; C3: 3 solitary zooids, 8 aggregate zooids, 5°28'54.80"N, 103°22'55.42"E, Jun 2016; D3; 3 solitary zooid, 3 aggregate zooids, 5°15'50.06"N, 103°17'44.13"E, July 2016. Malaysia: East Cost of Peninsular Malaysia. UMTTn 0004. Description. Solitary (Fig. 2a–b, 2d): 3.6–8.4 mm long, excluding posterior projections. Body elongated cylindrical. All test echinate, especially projections, strongly papillated all over the test. Test cylindrical, thickened ventrally around nucleus, with two long posterior projections. Oral opening terminal, atrial opening postero-dorsal. Atrial palps bifurcate. Medioventral projections well developed and lower one longer than upper one. Lateral projections well developed, fairly long. Body muscles thick. Five body muscles, MI to MIV continuous dorsally and ventrally, MV interrupted ventrally. MI to MIII and MIV to MV contiguous or fused in mid-dorsal line. Intermediate muscle interrupted dorsally and converge to MI. the number of muscle fibres varies from 77–106. Dorsal tubercle simple and small, separated from ganglion with short distance. Branchial septum slender, extending from ganglion to gut. Endostyle thin, extending from behind oral to posterior ventrally. Gut forming a compact nucleus, stolon coiled around it. Aggregate (Fig. 2c, 2d): 0.8 mm long. Body pentagonally shaped anteriorly with relatively hard, sharp-edged test. Test echinated. Sharply pointed posterior. The attachment organs vary in number and never protruding beyond test wall left posterior. Body muscles MI–MIII and MIV–MV fused over a short section. Muscle bands are wide, number of muscle fibres is usually 16. Gut forming a compact oval nucleus. Nucleus projection absent. The endostyle is short, only nearing to the MII. Ovary and embryo are situated on MIV, close to the nucleus. The gill are slender. Remarks. Both solitary and aggregate zooids of this species were collected during this study. Both stages agrees with the description by Yount in 1954, van Soest in 1973 and Purushothaman et al. in 2017. Distributions. T.rhomboides seems to be restricted to the Indo-Pacific waters (van Soest 1973), and to date there is still no record of this species found to be present in the Atlantic. It was first found by Quoy & Gaimard (1834) and recorded as Salpa pyramidalis on Agulhas Bank in the southeast African waters of the Indian Ocean, as did Borgelt (1968). It has been found in the Red Sea and Gulf of Suez (Godeaux 1974), Gulf of Aden (Godeaux 1987). Yount (1954) has recorded the presence of this species in the Central Pacific Ocean while Takioka (1960) found it in the South Pacific Ocean. Distribution from the North Pacific Ocean includes the records from the East coast of middle Japan (Tokioka 1937), Kaoping Trench of southwestern waters of Taiwan (Tew & Lo 2005), Eastern Tropical Pacific off Mexico (Hereu et al. 2010), Korean waters (Kim et al. 2011), the Kuroshio Extension and the Oyashio–Kuroshio mixed Water Region (Takahashi et al. 2013) and Taiwan waters (Liao et al. 2013 & Franco et al. 2017). The compilation of previous literature and present data distribution of Thalia rhomboides is shown in Figure 3. 2. Thalia sibogae van Soest, 1973 Thalia democratica var. orientalis (Takioka 1967) Thalia sibogae van Soest, 1973: 204–205, 1998: 239 fig. 14.3, table 14.3; Kim 2011: 147–149; Purushothaman et al. 2017 Specimens examined. A1: 1 solitary zooid, 1 aggregate zooid, 5°38'53.08"N, 102°58'39.07"E, April 2016; A3: 8 aggregate zooids, 5°40'51.01"N, 103° 1'51.06"E, April 2016; A4: 1 solitary zooid, 1 aggregate zooid, 5°38'6.00"N, 103° 3'48.06"E, April 2016; A6: 2 aggregate zooids, 5°39'50.59"N, 103° 9'36.64"E, April 2016; C1: 1 aggregate zooids, 5°20'47.59"N, 103° 8'59.91"E, Jun 2016; C2: 9 solitary zooids, 45 aggregate zooids, 5°25'33.93"N, 103°17'32.72"E, Jun 2016; C3: 8 solitary zooids, 30 aggregate zooids, 5°28'54.80"N, 103°22'55.42"E, Jun 2016; D2: 1 solitary zooid, 5°14'5.20"N, 103°16'36.04"E, July 2016; D3; 1 solitary zooid, 10 aggregate zooids, 5°15'50.06"N, 103°17'44.13"E, July 2016. Malaysia: East Cost of Peninsular Malaysia. UMTTn 0005. 454 · Zootaxa 4422 (4) © 2018 Magnolia Press AHMAD ISHAK ET AL. FIGURE 2a. Thalia rhomboides (Quoy & Gaimard, 1824). Top, Solitary, dorsal view; Bottom, ventral view. Br, branchial septum; Dt., dorsal tubercle; End, endostyle; G, ganglion, i.m., intermediate muscle; Lp. Lateral projection, ; Mp., medioventral projection; N, nucleus ; o.m., oral musculature; Pp., posterior projection. SALPS FROM THE EAST COAST OF PENINSULAR MALAYSIA Zootaxa 4422 (4) © 2018 Magnolia Press · 455 FIGURE 2b. Thalia rhomboides (Quoy & Gaimard, 1824). Top, Solitary, lateral view; Bottom, posterior part. Ap., atrial palp; Br, branchial septum; Dt., dorsal tubercle; End, endostyle; G, ganglion, i.m., intermediate muscle; Lp. Lateral projection, ; Mp., medioventral projection; N, nucleus ; o.m., oral musculature; Pp., posterior projection. 456 · Zootaxa 4422 (4) © 2018 Magnolia Press AHMAD ISHAK ET AL. FIGURE 2c. Thalia rhomboides (Quoy & Gaimard, 1824). Top, Aggregate, ventral view; Bottom, Stolon, dorsal view. Br, branchial septum; Dt., dorsal tubercle; End, endostyle; G, ganglion, i.m., intermediate muscle; N, nucleus ; o.m., oral musculature; Pp., posterior projection. SALPS FROM THE EAST COAST OF PENINSULAR MALAYSIA Zootaxa 4422 (4) © 2018 Magnolia Press · 457 FIGURE 2d. Drawing of Thalia rhomboides (Quoy & Gaimard, 1824). Left, Solitary; Right, aggregate zooid. Ap., atrial palp; Br, branchial septum; Dt., dorsal tubercle; End, endostyle; G, ganglion, i.m., intermediate muscle; Lp. Lateral projection, ; Mp., medioventral projection; N, nucleus ; o.m., oral musculature; Pp., posterior projection. 458 · Zootaxa 4422 (4) © 2018 Magnolia Press AHMAD ISHAK ET AL. FIGURE 3. Distribution of Thalia rhomboides (Quoy & Gaimard, 1824). Red dots: specimen examined by the author; black dots: records based on compilation of previous literature data. Description. Solitary (Fig. 4a–c, 4e): 4.8–8.8 mm long. Test firm, rounded, and smooth except for test projections and edge around the oral aperture. Atrial palps is fairly small and bifurcate. Posterior projections fairly short. Lateral projections very short. Medioventral projections are small and of uneven length, upper one shorter than lower one. Muscle bands broad, MII–IV touch dorsally, MV–MVI near but do not touch dorsally. Number of muscle fibres 56–84. Aggregate (Fig. 4c, 4e): 4.8 mm long. Body oval with test bulkily rounding anteriorly. Test smooth. Anterior part is somewhat rounded, with posterior pointed pentagonally. The attachment organs variable in number and never protruding beyond test wall left posterior. Body muscles MI–MIII and MIV–MV fused over a short section. Muscle bands are wide, number of muscle fibres is usually 16. Gut forming a compact nucleus. The endostyle is short, only nearing to the MII. Ovary and embryo is situated on MIV, close to the nucleus. The gill is slender. Remarks. Solitary and aggregate zooids of this species were collected during this study. For solitary zooid, van Soest describe of his specimen as having no lateral projection, while Kim et al. in 2011 reported that his specimen has a very short lateral projection. In this specimen, because of the presence of the short lateral projection, we would say that this specimen is resembling Kim’s specimen. Aggregate zooid closely resembles the description by van Soest in 1973. Distribution. T.sibogae occurrence is very scarce. There are very few literature that record the presence of this species in their specimen. Distribution from Pacific Ocean includes the record from East coast of middle Japan (Tokioka 1937), Bohol and Limosana Island of Philippine archipelago (Van Soest 1973), Central Indo-Pacific (van der Land 2008) and Korean waters (Kim et al. 2011). The compilation of previous literature and present data distribution of Thalia sibogae is shown in Figure 5. 3. Weelia cylindrica Cuvier, 1804 Salpa cylindrica Cuvier, 1804 (cited from van Soest 1973); (Ritter & Byxbee 1905); (Survey 1918); (Tokioka 1937); Thompson 1948; Godeaux 1998 Iasis cylindrica Savigny, 1816 (cited by Kott 2005); Franco et al. 2017; Purushothaman et al. 2017 Salpa coerulescens Chamisso 1819 (cited by Kott 2005) Weelia cylindrica; (Yount 1954); Van Soest 1975, 1998; Al-Yamani et al. 2011; Hereu & Suárez-Morales 2012 Specimens examined. 1 solitary zooids, 17 aggregate zooids, 5°25'33.93"N, 103°17'32.72"E, Jun 2016. Malaysia: East Cost of Peninsular Malaysia. UMTTn 0006. SALPS FROM THE EAST COAST OF PENINSULAR MALAYSIA Zootaxa 4422 (4) © 2018 Magnolia Press · 459 FIGURE 4a. Thalia sibogae (van Soest, 1973). Top, Solitary, dorsal view; Bottom, ventral view. Br, branchial septum; Dt., dorsal tubercle; End, endostyle; G, ganglion, i.m., intermediate muscle; Lp. Lateral projection; Mp., medioventral projection; N, nucleus; o.m., oral musculature; Pp., posterior projection. 460 · Zootaxa 4422 (4) © 2018 Magnolia Press AHMAD ISHAK ET AL. FIGURE 4b. Thalia sibogae (van Soest, 1973). Top, Solitary, lateral view; Bottom, posterior part. Ap., atrial palp; Br, branchial septum; Dt., dorsal tubercle; End, endostyle; G, ganglion, i.m., intermediate muscle; Lp. Lateral projection, Mp., medioventral projection; N, nucleus ; o.m., oral musculature; Pp., posterior projection. SALPS FROM THE EAST COAST OF PENINSULAR MALAYSIA Zootaxa 4422 (4) © 2018 Magnolia Press · 461 FIGURE 4c. Thalia sibogae (van Soest, 1973). Top, Aggregate, ventral view; Bottom, Chain of aggregate zooids. Br, branchial septum; Dt., dorsal tubercle; End, endostyle; G, ganglion, i.m., intermediate muscle; N, nucleus ; o.m., oral musculature; Pp., posterior projection. 462 · Zootaxa 4422 (4) © 2018 Magnolia Press AHMAD ISHAK ET AL. FIGURE 4d. Comparison between A: Thalia sibogae (van Soest, 1973) and B: Thalia rhomboides (Quoy & Gaimard, 1824). Top, Solitary, dorsal view, showing length of posterior projections; Bottom, body test part showing presence of echination. Description. Solitary (Fig. 6a, Top; 6b): Body length reaches 20.7 mm. Body is elongated and cylindrical; rounded anteriorly, and squarely cut off posteriorly. The test is thin, soft and smooth with no projection or echination. There are 9 body muscles that extend rather far ventrally and are usually separated. The first four body muscles; MI–MIV are seen closely approaching in the mid-dorsal line. The muscle fibers for MI–MIX is a total of 181. There are 3 sphincters present in the upper lip. The broad oral retractor, after crossing the intermediate muscle and the 3rd sphincter of the upper lip, gives 2nd sphincter where it appears to be continuous across the middle line. The retractor finally divided into the 1st short sphincter of the upper lip and the 1st and 2nd sphincters of the lower lip, which both the lower lips are continuous across the middle line. The transverse ribs of the gill bar meet dorsally, narrowing sharply toward the ventral surface, so that they are far apart from one another ventrally. The dorsal tubercle is a simple elongated arched stick. The alimentary canal is coiled into a tight nucleus. The gill is long and slender. Stolon runs forward in a straight course on the mid ventral line. There is no outgrowths from the ganglion. SALPS FROM THE EAST COAST OF PENINSULAR MALAYSIA Zootaxa 4422 (4) © 2018 Magnolia Press · 463 FIGURE 4e. Drawing of Thalia sibogae (van Soest, 1973). Left, Solitary; Right, aggregate zooid. Ap., atrial palp; Br, branchial septum; Dt., dorsal tubercle; End, endostyle; G, ganglion, i.m., intermediate muscle; Lp. Lateral projection; Mp., medioventral projection; N, nucleus ; o.m., oral musculature; Pp., posterior projection. Aggregate (Fig. 6a, Bottom, 6b): Body length reaches 3.1 mm. Body is oval in form, with short hollow projections anteriorly and posteriorly present, which are slightly asymmetricaly arranged. The test is voluminous, thickly fusiform, soft and smooth with no echination. Five body muscles, all approaching in the mid-dorsal line in two separate groups; MI–MIII are merged in the mid-dorsal region as are MIV–MV; the two groups for the most part touch in the mid-dorsal line. The MV is branched, where its posterior branches on each side passing the base of the atrial siphon; and it unites behind the siphon. The transverse ribs of the gill bar meet dorsally, tapering severely toward the ventral surface, so that they are far-off from one another ventrally. The dorsal tubercle is a simple elongated arched stick. The alimentary canal is coiled into a tight nucleus. The gill is thick and short. Ovary and embryo are situated at MIV ¼. Remarks. Both solitary and aggregate zooids of this species were found during the sampling of this study. According to Sewell in 1926 (p. 81, fig. 11), in the solitary stage some specimens have ten body muscles instead of nine while van Soest in 1975a (p. 111) stated that specimens from Atlantic Ocean were found to have 8 body muscles instead of nine. This specimen has nine body muscles. Sewell (p. 81, fig. 10, A–D) have also notes the fours variations in the connections of the MI–MIV. The four anterior muscles of this specimen were observed to be closely matching with variation A, where the first MI–MIII muscles are connected together and MIV is approaching MIII. Metcalf in 1918 (p. 95) describes the oral musculature as “consisting of an oral retractor, which 464 · Zootaxa 4422 (4) © 2018 Magnolia Press AHMAD ISHAK ET AL. give rise to two sphincters of the lower lip and is connected with the 1st sphincter of the upper lip, a broad independent 2nd sphincter of the upper lip, and the intermediate muscle, both of these latter lying internal to the retractor”. From near the dorsal end of the intermediate muscle, a short horizontal muscle runs forwards. Sewell states that in two large Indian Ocean specimens examined by him, there was an additional sphincter in the upper lip. There are 3 sphincters present in the upper lip (p. 80, fig. 9). This specimen resembles of Sewell’s but with a slight different on the upper lip length. The broad oral retractor, after crossing the intermediate muscle and the 3rd sphincter of the upper lip, gives of a 2nd sphincter where it appeared to be continuous across the middle line. The retractor divided into the 1st short sphincter of the upper lip and the 1st and 2nd sphincters of the lower lip, which both the lower lips are continuous across the middle line. A distinct variation is also found in the number of muscular fiber. Van Soest (p. 112) stated the number of fibers could varies from 91–261 fibers. In this specimen, for MI–MIX there is a total of 181 muscle fibers. For aggregate zooids, this specimens closely resemble of Thompson’s rather than the elongated variation collected from Goa by Dr. S.W. Kemp as noted in Sewell (p. 82, fig. 12). FIGURE 5. Distribution of Thalia sibogae (van Soest, 1973). Red dots: specimen examined by the author; black dots: records based on compilation of previous literature data. Distribution. Weelia cylindrica is the most common species of Salpidae (van Soest 1975), widely distributed in the Atlantic, Indian and Pacific Ocean. Records from the Atlantic Ocean includes of Dall’s (1871), occurrence on the coast of Rhode Island and Block Island (Metcalf 1918), Sardinera Lagoon of Puerto Rico (Tokioka & Bhavanarayana 1979), Harbison et al. (1978), Harbison & Campenot (1979), Pomeroy & Deibel (1980), Madin & Cetta (1984), Caron et al. (1989), southeast of Bermuda (Madin et al. 1996), Mid-Atlantic Bight (Vargas & Madin 2004) and Caribbean Sea and the Gulf of Mexico (Hereu & Suárez-Morales 2012). It has also been found in the Arabian Sea (including the Laccadive Sea), the Bay of Bengal and the Andaman Sea (Sewell 1926), Red Sea and Gulf of Suez (Godeaux 1974; Al-Yamani et al. 2011 & Kannathasan, et al. 2014), Gulf of Aden & Hanish Hill (Godeaux 1987). Records found from the Pacific Ocean includes (Yount 1954; 1958), Australian Seas (Herdman 1891 & Thompson 1948), Ritter & Byxbee (1905), Great Barrier Reef lagoon (Russell & Colman1935), Province of Izu (Tokioka 1937; 1960) California Current region (Berner 1967), Florida Current and Gulf of California Mexico (Madin 1974; Felder & Camp 2009), Bermuda (Madin et al. 1996), European waters (van der Land & van Soest 2001), Mid-Atlantic Bight (Vargas & Madin 2004), Kaoping Trench, southwestern waters of Taiwan (Tew & Lo 2005), coast of Panama (Sutherland 2010), eastern tropical of Mexico (Hereu et al. 2010), Taiwan waters (Liao et al. 2013 & Franco et al. 2017), Singapore Straits (Tey 1967), northwest continental shelf of South China Sea (Li et al. 2011), Sabah, Borneo of Malaysia. The compilation of previous literature and present data distribution of Weelia cylindrica is shown in Figure 7. SALPS FROM THE EAST COAST OF PENINSULAR MALAYSIA Zootaxa 4422 (4) © 2018 Magnolia Press · 465 FIGURE 6a. Weelia cylindrica (Cuvier, 1804). Top, Solitary; Bottom, Aggregate. Br, branchial septum; Dt., dorsal tubercle; End, endostyle; G, ganglion, i.m., intermediate muscle; N, nucleus; o.m., oral musculature. 466 · Zootaxa 4422 (4) © 2018 Magnolia Press AHMAD ISHAK ET AL. FIGURE 6b. Drawing of Weelia cylindrica (Cuvier, 1804). Left, Solitary; Right, aggregate. Br, branchial septum; Dt., dorsal tubercle; End, endostyle; G,ganglion, i.m., intermediate muscle; N, nucleus; o.m., oral musculature. 4. Brooksia rostrata Traustedt, 1893 Salpa rostrata Traustedt, 1893, pp. 8, pl. I, figs. 1–4 (cited in Thompson 1948 and Sewell 1926; Apstein, 1894, pp. 16, 36, pl. ii, figs. 9, 17–19 (cited in Sewell 1926) Brooksia rostrata Metcalf, 1918, pp. 50 (cited in Sewell 1926); Fraser, 1947; Thompson, 1948: 120, pl. 43, pl. 45; Yount, 1954; van Soest, 1975; Chihara & Murano, 1997: 1381, pl. 7; Godeaux: 1998, pp. 287, fig. 17.16c; Kott, 2005; Hereu & SuárezMorales, 2012; Garic & Batistic, 2016; Purushothaman et al. 2017; Franco et al. 2017 Specimens examined. In my study, this species was the present at 5 sampling sites. C2: 15 solitary zooids, 31 aggregate zooids, 5°25'33.93"N, 103°17'32.72"E, Jun 2016; C3: 16 solitary zooids, 13 aggregate zooids, 5°28'54.80"N, 103°22'55.42"E, Jun 2016; D1: 1 aggregate zooid, 5°14'5.31"N, 103°14'40.12"E, July 2016; D2: 4 aggregate zooid, 5°14'5.20"N, 103°16'36.04"E, July 2016; D3; 3 aggregate zooids, 5°15'50.06"N, 103°17'44.13"E, July 2016. Malaysia: East Cost of Peninsular Malaysia. UMTTn 0007. Description. Solitary (Fig. 8a, Top & Middle; 8b): Body length reach 4.3 mm without anterior projection, and reaching 6 mm including the anterior projection. Body is elongatedly cylindrical; squaring posteriorly while strongly developing a projection anteriorly, below the lower lip, bearing four longitudinal muscles; which are extensions of the dorsal sphincters, and two ventral longitudinal muscles. The projection may be as long as the SALPS FROM THE EAST COAST OF PENINSULAR MALAYSIA Zootaxa 4422 (4) © 2018 Magnolia Press · 467 body, although in most specimen it is shorter. The test is lost in this specimen. There are 7 body muscles observed in the specimens. The muscles are arranged in two dorsal group (MI–MIII and MIV–MVII), where MI is joined by the intermediate muscle and MIII and MIV are converging laterally. The body muscles are ventrally interrupted by two longitudinal muscles which run from MVII to the anterior tip of the anterior projection. The dorsal tubercle located close in front of the ganglion, very slightly curved. The ganglion carries the broad horseshoe eye and located in front of MI. The alimentary canal is coiled into a loose nucleus, located immediately behind MVII. The endostyle is slightly curved, reaches back to at least near MIV. Ihle states that it reaches between MIV and MV, but according to Traustedt it only reaches to MIII. This specimen resembles more to Ihle than to Traustedt. The gill is slender. Stolon runs forward in a more or less straight course on the mid ventral line. FIGURE 7. Distribution of Weelia cylindrica (Cuvier, 1804) Red dots: specimen examined by the author; black dots: records based on compilation of previous literature data. Aggregate (Fig. 8a, Bottom; 8b): Body is oval shaped. The test is lost in this specimen. Due to the poor state of preserved specimens, it is impossible to study the body muscles. Van Soest (p. 116) stated the number of fibers could vary from 14–26 fibers. This specimen agree to the range of fibers count. The alimentary canal is coiled into a rather tight nucleus, which lies at the posterior most part of the body. The endostyle is short, bent to a hook in front, near its point of origination neighboring behind the oral siphon. Ovary and embryo is situated between MIII and M IV on the right side. The gills are slender. Remarks. Both solitary and aggregate zooids of this species were found during the sampling of this study. The aggregate seems to be unfit for critical taxonomy study due to poor preservation that caused specimen shrinkage. The solitary and aggregate zooids conforming to Thompson's (1948) figures. Fedele (1926) figured an aggregate specimen with very long attachment organs; no such specimens were encountered in the present material. Distribution. Distributional data on Brooksia rostrata reported that it mainly occurred in temperate waters (van Soest 1975). Records from the Atlantic Ocean includes the occurrence on southeast of Bermuda (Madin et al. 1996) and Caribbean Sea and the Gulf of Mexico (Hereu & Suárez-Morales 2012). It has also been found in the Arabian Sea (including the Laccadive Sea), the Bay of Bengal and the Andaman Sea (Sewell 1926), Gulf of Naples (Fedele 1926), Red Sea and Gulf of Suez (Godeaux 1974), Gulf of Aden and Hanish Hill (Godeaux 1987) and Adriatic Sea (Sigl 1912; Batistić et al. 2014). Records found from the Pacific Ocean includes (Yount 1954; 1958), Australian Seas (Thompson 1948), Province of Izu (Tokioka 1937; 1960), European waters (Costello et al. 2001), Kaoping Trench, southwestern waters of Taiwan (Tew & Lo 2005), Taiwan waters (Liao et al. 2013 & Franco et al. 2017) and Indo-West Pacific (van der Land 2008). The compilation of previous literature and present data distribution of Brooksia rostrata is shown in Figure 9. 468 · Zootaxa 4422 (4) © 2018 Magnolia Press AHMAD ISHAK ET AL. FIGURE 8a. Brooksia rostrata (Traustedt, 1893). Top, Solitary zooid; Middle, posterior part; Bottom, Aggregate. Br, branchial septum; Dt., dorsal tubercle; End, endostyle; G, ganglion, i.m., intermediate muscle; N, nucleus; o.m., oral musculature. SALPS FROM THE EAST COAST OF PENINSULAR MALAYSIA Zootaxa 4422 (4) © 2018 Magnolia Press · 469 FIGURE 8b. Drawing of Brooksia rostrata (Traustedt, 1893). Left, Solitary; Right, aggregate. Br, branchial septum; Dt., dorsal tubercle; End, endostyle; G, ganglion, i.m., intermediate muscle; N, nucleus; o.m., oral musculature. FIGURE 9. Distribution of Brooksia rostrata (Traustedt, 1893). Red dots: specimen examined by the author; black dots: records based on compilation of previous literature data. 470 · Zootaxa 4422 (4) © 2018 Magnolia Press AHMAD ISHAK ET AL. Key to the life cycles of Salpidae species 1. - Animals bearing a stolon emerging ventrally or posteriorly, gonad always absent, oozooid or solitary form . . . . . . . . . . . . . A Animals bearing one or several eggs or embryos on the posterior right, stolon always absent, blastozooid or aggregate form .B Key to salp species from East coast of Malay Peninsular A. Oozooids or solitary forms 1 2 3 - Five body muscle, test bearing projections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 More than five body muscles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Test papillated strongly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thalia rhomboides Test smooth and bulky . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thalia sibogae Seven body muscles continuous in two dorsal groups (M I–III and M IV–VII), M III and M IV touching or fusing laterally, a long proboscis bearing longitudinal muscles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Brooksia rostrata Nine body muscles; M I to M IV fused or closely approaching dorsally, test smooth . . . . . . . . . . . . . . . . . . . Weelia cylindrica B. Blastozooids or aggregate forms 4 5 6 - Body asymmetrical, body muscles conjoining ventrally and dorsally as a simple mass, body oval . . . . . . . . Brooksia rostrata Body muscles symmetrically arranged . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Two groups of body muscles, M I–III and M IV–V fusing or closely approaching dorsally, body fusiform. . Weelia cylindrica Two groups of body muscles, M I–III and M IV–V fusing or closely approaching dorsally, body oval . . . . . . . . . . . . . . . . . 6 Posterior part of the test rounded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thalia sibogae Posterior part of the test pentagonal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thalia rhomboides Discussion Taxonomy. In the present study, focus was on the taxonomy, diversity and biogeography of Salpidae in the east coast of Malaysia. Of the four species found in Terengganu waters, identification for the three different Genus was straightforward as they have distinct morphological characteristics. However, the identification of the species within the genus Thalia; for T.rhomboides and T.sibogae proves to be a bit challenging. The most distinct character between the two species was their muscle fibers count. The muscle fibers for Thalia rhomboides range from 84– 108, while the muscle fibers for Thalia sibogae range from 62–90. Foxton in 1961 concluded that the most important taxonomic character to differentiate between thaliaceans species was the total number of muscle fibers based on the finding of research done by Apstein (1906), Takioka (1937), Sewell (1953) and Berner (1954). The importance of muscle fibers was again highlighted in the recent studies by Hereu et al. in 2014 which mentioned that Helicosalpa komaii was distinguished from the other 2 species of the genus by its total number of muscle fibers (M I–M VII). Moreover, Esnal et al. (1998) stated that chemical will have no effect on this characteristic. Aside from having different range of muscle fibers count, these two species also have few other different morphological characteristics (Fig. 4d). T.rhomboides seems to have an elongated cylindrically body with strong echination all over the test and fairly long posterior and lateral projection. Both solitary and aggregate zooids of this species were collected during this study. Both stages agrees with the description by Yount in 1954, van Soest in 1973 and Purushothaman et al. in 2017. T.sibogae has rounded bulky body with smooth test except for test projections and ridge around oral aperture and both posterior and lateral projections is fairly short. For solitary zooid, van Soest describe of his specimen as having no lateral projection, while Kim et al. in 2011 reported that his specimen has a very short lateral projection. In this specimen, because of the presence of the short lateral projection this specimen is resembling Kim’s specimen. Aggregate zooid closely resembles the description by van Soest in 1973. Distribution and biogeography. Salps although patchily distributed, are a significant component of zooplankton communities in the open ocean due to their wide coverage of distribution (Van Soest 1975b; Kashkina 1978). In the South China Sea, a total of 13 species were observed (Zhang et al. 2003; Liao et al. 2013; Franco et al. 2017). Fraser (1962) stated that the biogeography of salps is crucial to be investigate due to few species have been use as the indicators of ocean currents and the interferences of warm oceanic waters into colder zones. This claim can be supported by findings of Blackburn (1979), McAlice (1986), Sims (1996) and Iguchi & Kidokoro (2006) where species such as Salpa fusiformis is often associated as colder water species, and the presence of SALPS FROM THE EAST COAST OF PENINSULAR MALAYSIA Zootaxa 4422 (4) © 2018 Magnolia Press · 471 warmer water species such as Thalia democratica and Thetys Vagina often indicates the rising of water temperature. In our study, we found a total of 4 salp species; Thalia rhomboides, Thalia sibogae, Brooksia rostrata and Weelia cylindrica; in Terengganu waters during the southwest monsoon. These four species occurring simultaneously in the same station only happened once, where the sample was taken in the open water area which had the highest temperature amongst other station. This finding is consistent with Liao et al. (2013) whom stated that salps favor waters of higher salinities and higher temperatures; 24–31° C; which provide suitable conditions to enhance their asexual reproduction. We also observed that in Malaysian waters, Thalia sibogae was the most abundant species. It is a surprise to discover that Thalia sibogae dominates the collection of Salpida from Terengganu waters as Thalia sibogae can be considered as one of the least encountered of Thalia species, with little record of its occurrences restricted to 100º– 140ºE, 0º–40ºN area. Van Soest in 1973a firstly described the species using specimens from the type locality of Celebes Sea and from a specimen caught in the Philippine Archipelago by the Albatross Expedition in 1908. The most recent record comes from South Korea where Kim et al. (2011) found 9 solitary zooids but no aggregate zooids of this species were collected during the study. Van Soest (1975b) had previously stated that this species is a warm-water species which seem to be restricted to tropical areas of the Indian Sea and Pacific Ocean only. This finding somehow seems to agree to what Van Soest previously stated, as the result helps to expand out the distribution discovery, but still restricted to the Pacific Ocean. TABLE 1. Thaliaceans encountered in the China Sea from previous literature. Taiwan waters Korea waters (Franco et al. 2017) (Kim et al. 2010; 2011; 2012) Singapore Straits (Yap & Lee 2016) Terengganu waters (present study) Family: Salpidae Thalia democratica / / Thalia orientalis / / Thalia cicar / / Thalia sibogae / / / / / Thalia longicauda Thalia rhomboides / Brooksia rostrata / Weelia cylindrica / Soestia zonoria / Salpa fusiformis / Salpa maxima / Traustedtia multitentaculata / Pegea confoederata / Ihlea punctata / Ritteriella amboinensis / Ritteriella picteti / / / / / / / Cyclosalpa bakeri Cyclosalpa pinnata / Cyclosalpa affinis / / Cyclosalpa polae / / Cyclosalpa quadriluminis / Cyclosalpa sewelli / Cyclosalpa floridana / 472 · Zootaxa 4422 (4) © 2018 Magnolia Press / AHMAD ISHAK ET AL. Uncollected thaliaceans species. Analyzing and comparing the studies of thaliaceans distribution from China Sea (Table 1), we observed that there are species which were recorded in the China Seas that could not be identified from Terengganu waters as yet: Thalia democratica, Thalia orientalis, Thalia cicar, Thalia sibogae, Thalia longicauda, Thalia rhomboides, Soestia zonoria, Salpa fusiformis, Salpa maxima, Traustedtia multitentaculata, Pegea confoederata, Ihlea punctata, Ritteriella amboinensis, Ritteriella picteti, Cyclosalpa bakeri, Cyclosalpa pinnata, Cyclosalpa affinis, Cyclosalpa polae, Cyclosalpa quadriluminis, Cyclosalpa sewelli and Cyclosalpa floridana which all belong to the class Salpidae. The thaliaceans diversity result of this study might be undervalued due to a few limitations throughout the course of the study. In fact, our research was conducted within a span of four months within a year and not throughout a single year and that the area coverage for the sampling site is limited. This could cause some problems for the comparison with other kind of work of the same nature. Next, deep-water or seasonally restricted occurrences may also influence the results of the study. The collection of organisms was carried out at restricted regions covering only the southwest monsoon season and at an average depth of 15 m. Through sampling in deeper waters and with a wider sampling location, we could expect to have found a higher diversity of species of salps. Although with several limitations, this study provides valuable baseline information regarding the distribution of salps in Malaysian waters given that there are no historical records of Thalia rhomboides, Thalia sibogae, Weelia cylindrica and Brooksia rostrata have been previously identified in the area and at the same time extends the latitudinal distribution of these species in the South China Sea. It could also serve as a starting point for further research, especially about the ecology of these organisms. 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