Janaira platyoura, Doti, Brenda Lía & Wilson, George D. F., 2010

Janaira platyoura View in CoL sp. nov.

( Figs 15–20 View FIGURE 15 View FIGURE 16 View FIGURE 17 View FIGURE 18 View FIGURE 19 View FIGURE 20 )

Etymology. The species name is combined from the Greek "platy" meaning flat and "oura" meaning tail, alluding to the flattened uropods present in this species.

Type fixation. Holotype brooding Ƥ, 1.5 mm, P.81231, here designated.

Type locality. Australia, New South Wales, Batemans Bay, northwest side of Tollgate Island, NSW 2001, 35º44.82’S, 150º15.53’E, 7.9 m, coll. by G.D.F. Wilson & A.J.K. Millar, 28 Oct 2002, among Caulerpa flexilis (alga).

Paratypes. 3 (1.3 mm), P.81232; BƤ (1.5 mm), P.81233, dissected; 3, P.81234, dissected; 56 inds, P.81235; Ƥ, P.81116, SEM stub MI176; 3, P.81117, SEM stub MI177; 896 inds, ethanol preservation only, P.81236.

Other material. Australia, New South Wales. Jervis Bay, Bowen Island, 35º6.81'S, 150º46.11'E, coll. by G.D.F. Wilson & P. Serov, 0 8 Dec 1993: 3 ƤƤ, 1 3, P.84101, NSW 932, 13 m, among dense bryozoans under rock ledge.

Twin Peaks, ~ 6 n. mi. from Tathra, ~ 1.5n.mi. east of Wharf at Gillards Beach, 36º40.12'S, 150º1.06'E, coll. by G.D.F. Wilson & J. Eu, 26 Mar 2001: 3 3, P.84094, NSW 1793, 25 m, among white bushy hydroid tufts.

Bitangabee Bay (Inlet), ~ 4 n. mi. north of Green Cape, 37º12.88'S, 150º1.02'E, coll. by A.J.K. Millar & party, 27 Mar 2001: 1 3, P.84095, NSW 1806, 6 m, among surface plankton (may be a contaminant from another sample).

Broulee Island, south of Batemans Bay, 35º50.83'S, 150º11.09'E, coll. by A.J.K. Millar & party, 25 Oct 2002: 4 3, 1 Ƥ, P.84096, NSW 1989, 8 m, among branching coralline algae Amphiora anceps & Jania natalensis ; 63 inds, P.84097, NSW 1990, 8 m, among Halopteris platycena (alga); 1 Ƥ, 1 3, P.84098, NSW 1991, 8 m, among Zonaria diesingiana (alga).

Burrewarra Point, Gutters, south of Batemans Bay, 36º40.12'S, 150º1.06'E, coll. by A.J.K. Millar & party, 27 Oct 2002: 1 3, P.84099, NSW 1996, 24 m, among Pachymenia prostrata (alga); 1 Ƥ, P.84100, NSW 1997, 23 m, among Codium lucasii (alga).

Batemans Bay, Tollgate Islands, 35º44.83'S, 150º15.53'E, coll. by A.J.K. Millar & party, 28 Oct 2002: 12 inds (2 BƤƤ, 10 3), P.84102, NSW 2003, 28 Oct 2002, 7.9 m, among Chondria succulenta (alga); 6 inds (1 Ƥ, 3 3, 2 juvs), P.84103, NSW 2005, 12 m, among Galaxuara marginata (alga); 14 inds (6 ƤƤ, 4 3, 4 juvs), P.84104, NSW 2006, 12 m, among Sporochnus radiciformis (alga).

Jimmy's Island, south of Batemans Bay, 35º48.94'S, 150º14.1'E, coll. by A.J.K. Millar & party, 29 Oct 2002: 5 inds (1 BƤ, 1 Ƥ, 3 3), P.84105, NSW 2009, 16 m, among Apjohnia laetevirens (alga) with epiphytic coralline red algae.

Batemans Bay, Tollgate Islands, coll. by A.J.K. Millar & party: 19 inds (13 3, 5 BƤƤ, juv. Ƥ), P.84106, NSW 2012, 29 Oct 2002, 35º44.76'S, 150º15.45'E, 12 m, among Asparagopsis taxiformi s (alga); 3, P.81401, NSW 2018, 24 Mar 2004, 35º44.84'S, 150º15.48'E, 11 m, among Asparagopsis armata (alga); 26 inds (4 BƤƤ, 6 ƤƤ, 14 3, 2 juvs), P.81400, NSW 2022, 0 8 Feb 2003, Batemans Bay, north Tollgate Island, 35º44.84'S, 150º15.48'E, 11 m, among Halopteris platycena (alga); 1 3, P.84108, NSW 2024, 0 8 Feb 2003, Batemans Bay, north Tollgate Island, 35º44.84'S, 150º15.48'E, 11 m, among mixed algae.

Broulee Island, south of Batemans Bay, coll. by A.J.K. Millar & party: 2 BƤƤ, P.84107, NSW 2017, 30 Oct 2002, 35º51.34'S, 150º11.64'E, 16 m, among Phacelocarpus pepperocarpus (alga).

Brush Island, Batemans Bay, 35º31.65'S, 150º24.96'E, coll. by A.J.K. Millar & party, 0 9 Feb 2003: 3 inds (2 3, 1 juv), P.84109, NSW 2031, 12 m, among Caulerpa flexilis (alga).

Burrewarra Point, south of Batemans Bay, 35º44.76'S, 150º15.45'E, coll. by P. Berents & party, 23–24 Mar 2004: 1 BƤ, 1 3, P.84110, NSW 2511, 17 m, among rock with Hydrodendron australe (hydroid) & other encrusting fauna; 1 BƤ, P.84111, NSW 2521, 35º49.78'S, 150º13.96'E, 13.4 m, among Amathia sp. (bryozoan).

Diagnosis. Head anterior margin in dorsal view sinuate with medial convexity; anterolateral margin angular, lateral margin linear. Eyes posterior margin adjacent to pereonite 1. Pereonites 1–7 lateral margins broadened, coxae covered, visible in dorsal view on pereonites 5–7 only. Pleotelson posterior margin broadly rounded, without posterior inflection. Antenna article 5 near length of articles 1–4 and shorter than head median length. Pereopod I of adult (terminal) male merus not elongate, near length of merus of posterior pereopods; carpus proximal width greater than distal width. Pleopod II of adult male endopod stylet curving laterally with no inflections. Uropod shorter than pleotelson, rami crossectional shape flattened with linear sides.

Description. Pigmentation in preservative scattered brown pigment. Body length of male 1–1.5 mm, female 1.5–2 mm (BƤ), male length 2.92 width, widest at pereonite 3 in both sexes.

Head ( Figs 15 View FIGURE 15 B; 18A, C). Width 1.53 length. Frontal margin sinuate, medial section rounded (concentrated in small projection between antennulae). Anterolateral margin angular. Eyes large, with more than 10 ocelli, length 0.46 head medial length, dorsolateral, extending to lateral margin.

Pereonites ( Fig. 15 View FIGURE 15 B). Pereonites 1–7 medial length ratios relative to pereonite 2: 0.71, 1.0, 1.47, 1.04, 0.47, 0.71, 0.66, respectively. Pereonites 2–3 laterally convex. Pereonite 4 laterally linear.

Pleon ( Figs 15 View FIGURE 15 B; 18D). Pleotelson length 1.2 width, lateral margin nearly straight flattened curve, denticles absent.

Antennula and Antenna ( Figs 15 View FIGURE 15 A–C; 18A–C; 19A). Antennula of male length 1.1 head median length, female length 1.46 head median length, with 9 articles in both sexes, article 1 length 1.29 width, article 2 length 1.55 article 3 length. Antenna length 1.1 body length, articles 1–6 length 0.37 body length, article 5 near length of articles 1–4 and shorter than head median length, article 5 length 1.35 article 6 length, flagellum with 45–50 articles.

Mouthparts ( Figs 15 View FIGURE 15 D–F; 16A–C). Mandible left spine row with 4 spines; right spine row with 7 spines; molar distal margin with paired blade-like ridges. Mandible palp length 0.98 mandibular body length, article 1 simple setae absent. Maxillula lateral lobe distal margin with 14 robust denticulate setae. Maxilla lateral lobes with 4 curved denticulate setae. Maxilliped palp article 2 width 1.28 endite width, article 3 distally subrectangular, distomedial margin with distinct inflection, in terminal male distomedial margin linear; endite length 1.56 width, with 2 receptaculi, distal margin with 4 fan setae.

Pereopod I ( Figs 16 View FIGURE 16 D–E; 18F). Coxa projecting anterolaterally, angular (but not visible in dorsal view). Pereopod I adult female length 0.84 body length. Carpus sexual dimorphism not pronounced, adult female carpus narrower and less robust than in male, approximately 40% narrower in adult female than in terminal male.

Pereopod I of adult (terminal) male ( Figs 16 View FIGURE 16 E; 19B). Length 0.5 body length; basis not elongate, near length of bases on posterior pereopods, basis length subequal to carpus. Ischium not elongate, near length of ischium on posterior pereopods, length 0.86 carpus length. Merus length 0.44 carpus length. Carpus with few short setae, robust setae in two rows, 5 robust setae altogether (3 medially, 2 laterally), width 0.4 length; ventral margin proximal to palm approximately linear, slightly sinuous. Propodus length 0.79 carpus length, ventral margin with 1 robust distal seta and without spines. Dactylus length 1.0 propodus distal width, well developed.

Pereopods II–VII ( Figs 17 View FIGURE 17 A–B). Pereopod II length 0.78 body length; coxa anterolateral margin rounded. Pereopod VII length 0.92 body length.

Pleopods ( Figs 17 View FIGURE 17 D–G; 19E, F). Operculum of female length 1.4 width, distal margin concave, with few setae. Pleopod I of adult male distal width 0.69 proximal width; dorsal surface stylet guides lateral margin without denticles; lateral lobe distal margin present, single, projecting posterolaterally, without setae; medial lobe with distinct indentation at inner margin of lateral lobe, margin convex, projecting posteriorly, width 1.25 pleopod (both sides) distal width, with 11–12 setae, of which 4–5 setae longer than others. Pleopod II of adult male protopod distal margin setae absent, endopod proximal article near maximum width of distal article, endopod stylet length 0.87 protopod length. Pleopod III exopod length 1.06 endopod and protopod length, distal margin acute, tapering to narrowly rounded tip, with 1 simple seta.

Uropods ( Figs 17 View FIGURE 17 C; 18D; 19C–E). Length in adult male 0.78 pleotelson length, length in adult female 0.75 pleotelson length. Protopod length 1.4 width, elongate trapezoidal, proximal width narrower than 0.5 distal width. Endopod length 1.85 protopod length, 1.14 exopod length.

Distribution. Jervis Bay to Batemans Bay region (NSW, Australia), 6–25 m ( Fig. 20 View FIGURE 20 ).

Remarks. Janaira platyoura sp. nov. differs from the type species, J. gracilis , by the following features (those of J. gracilis are in parenthesis): antennula with 9 articles (12 articles); antenna articles 5 and 6, each one shorter than the head (each one longer than the head); male pleopod I, medial lobes convex projecting posteriorly with a distinct indentation at inner margin of lateral lobe (medial lobes straight angling smoothly into posteriorly pointed lateral lobes); uropods rami broad and flat (thin and cylindrical). Since Janaira platyoura sp. nov. is the second species to be added to this genus, it provides new information that allows a revision of the definition of Janaira . Specifically, regarding the male pleopod I and the uropods, the interspecific variation in Janaira is unlike the consistency of form seen in other genera, such as Ianiropsis . The genus Carpias , however, also shows some variation in the morphology of the male pleopod I. As mentioned above, the genera Janaira , Carpias , Ianiropsis and Janira are similar in general habitus, and Wilson & Wägele (1994) found differences between Janaira and Janira to be subtle. Nevertheless, we conclude that the new species described herein is best placed in Janaira Moreira & Pires, 1977 owing to weakly modified pereopods I, and unmodified pereopods II of the adult male.

The male pleopod II protopod of Janaira platyoura sp. nov. has an unusual transverse fold on its ventral surface ( Fig.17 View FIGURE 17 G). This transverse fold was seen in several specimens and is not an artefact. This is a new structure and is not homologous to a podomere because it occurs distally and laterally to the exopod, and does not have intrinsic musculature.

J. platyoura sp. nov. appears to be limited to southern New South Wales ( Fig. 20 View FIGURE 20 ), extending from Green Cape (possibly - see Additional Material) to Jervis Bay. No specimens of this species were found outside NSW based on our inspection of the Australian Museum and Queensland Museum collections. J. platyoura was collected primarily on algae. In particular, the highest number of specimens were found on the algae Caulerpa flexilis and Halopteris platycena . This species was also found occasionally on bryozoans, which are a dominant structural component of benthic assemblages in southeastern Australia.