Wiyufiloides osornoensis, Pérez-Schultheiss & Wilson, 2021

Wiyufiloides osornoensis View in CoL gen. & sp. nov.

( Figs 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Aff. Anneckella sp. Pérez-Schultheiss, 2009: 151–152, Fig. 5 View FIGURE 5 .

Type Fixation. Holotype male, MNHNCL ISO-15132, here designated.

Holotype. ♂, body length 4.6 mm (MNHNCL ISO-15132): Ovejería, X-2012, Col. JPS.

Paratypes. Ovejería . 8-IX-2004, JPS , under stones, upwelling spring, at the base of a compacted gravel wall: ♀ (dissected, figured, photos) ( LACM: DISCO:19982), 1 ♀ 1 juv. specimen ( LACM: DISCO:19983), 1 ♀ ( LACM: DISCO:19984) . 16-X-2006, JPS & U. Mosqueira, spring filtration, between stones: ♀, body length 8.25 mm (MNHNCL ISO-15124), 1 ♂ 2 ♀ (MNHNCL ISO-15125), 1 dissected ♂ (MNHNCL ISO-15131). 25-IX-2007, JPS , Upwelling spring: 3 ♀ (MNHNCL ISO-15126). 11- IV- 2010, JPS & U. Mosqueira, Karaman-Chappuis in gravel-sand inlet, upwelling spring: 3 ♂ 3 ♀ (MNHNCL ISO-15123). X-2012, JPS , vertiente: 1 ♂ 6 ♀ (MNHNCL ISO-15128).

Ñadi Pichidamas, 2- IV- 2010, JPS, Upwelling spring: 2 ♀ (MNHNCL ISO-15127).

Other material. Ovejería. 10-IX-2011, JPS, Upwelling spring, collection with drift net: 1 damaged specimen, sex undetermined (MNHNCL ISO-15129).

Ñadi Pichidamas, 20-II-2011, JPS , Spring : 2 juv. specimens (MNHNCL ISO-15130) . 4-IX-2005, JPS , El Moro river tributary spring, between clay sediments: 1 ♀ ( LACM: DISCO:19988) .

Río Pilmaiquen, 15-IX-2005, JPS, Between stones, upwelling spring: 1 dissected ♂ (pls, figured) ( LACM: DISCO:19985), 2 juv. ( LACM: DISCO:19986), 1 ♀ ( LACM: DISCO:19987) .

Etymology. The new species is named for Osorno, the city where the first specimen was collected. The animal was found at the entrance of the neighbourhood called Ovejería, in a spring that flowed at less than 10 meters of a principal street, a place that years later was destroyed to construct a short by pass road.

Diagnosis. as for the genus.

Description. Body ( Fig. 1 View FIGURE 1 ). Colouration translucent white in life. Narrower anteriorly (pereionite 1 width 0.93 pereionite 6 width), pereion length 5.1 width. Largest male length 6.6 mm. Largest preparatory female length 8.4 mm. Largest brooding female length 8.2 mm.

Head ( Fig. 5A View FIGURE 5 ). Eyes absent. Length subequal to width, 0.98–1 width (F, M). Width 0.91–0.93 pereionite 1 width (♂, ♀). Anterior margin rostrate, with angular ridge rising from clypeus, interantennal lobes anteriorly projecting, obtusely angular.

Pereionites ( Fig. 1 View FIGURE 1 ) lateral margins convex (1–4 anteriorly, 5–7 projecting posteriorly), coxae visible in dorsal view as small arcs. Body margins narrower anteriorly, wider posteriorly (only slightly – 5% difference); lengths increasing posteriorly (relative to pereionite 1 lengths increasing from 1.1 to 1.5).

Anterior pleonites ( Fig. 5C View FIGURE 5 ). Pleonite 1 width 0.65 pereionite 7 width (N = 2). Pleonite 2 dorsal articulation not expressed, only pleonite 1 articulated.

Pleotelson ( Fig. 5C View FIGURE 5 ) with anterior inflection after pleonite 1, posteriorly rounded. Width 0.9–0.92 pereionite 7 width (F, M), maximum on anterior margin (at inflection point after pleonite 1); length 1.25–1.39 width. Lateral margin with around 21 setae; lateral margin smooth. Posterolateral margin without spines, margin uninterrupted.

Antennula ( Figs 2A View FIGURE 2 , 5A–B View FIGURE 5 ). Of male length 1.5 median head length, with 18 articles, article 1 length 1.7 width, article 2 length 1.6 article 3 length. Of female length 0.53 median head length, with 14 articles, article 1 length 1.7 width, article 2 length 1.6 article 3 length. Flagellum with aesthetascs, one each for third article onwards.

Antenna ( Figs 2B View FIGURE 2 , 5B View FIGURE 5 ). Of male length 0.58 body length. Of female length 0.67–0.73 body length. Articles 1–6 length 0.28 body length (male). Article 5 length less than articles 1–4 length, 0.71 article 3 length; article 6 longest. Flagellum with 32–56 articles. Scale vestigial, reduced to tiny articulated segment (with 2 setae).

Mandible ( Fig. 2C–D View FIGURE 2 ). Molar process penicil-like, terminating in large multispinulate spine, distally tapering and angular, posteromedial margin with 15–24 long and straight spinules, without setules. Incisor process with 5 cusps, without anterior tusk in male. Left lacinia mobilis three dentate. Spine row with 8–11 setae. Palp article 2 longest, with row of 6 short and two long robust setae in distal half, article 3 curved, with dense fringe of slender setae and two uneven distal strong setae.

Maxilla 1 ( Fig. 2F View FIGURE 2 ). Outer lobes as long as inner lobe, each with 2 long and 2 shorter distal setae. Inner lobe width 1.8 outer lobes width, lateral margin with 6 distal robust setae and 3 longer subdistal robust setae.

Maxilla 2 ( Fig. 2E View FIGURE 2 ). Lateral endite distal margin with 8 serrate robust setae and 4 simple robust setae.

Maxilliped ( Fig. 2G View FIGURE 2 ). Palp article 2 length around 1.8 article 1 or article 3 length. Basis endite reaching palp article 3, medial margin with 6 receptaculi. Basis endite subdistal margin without robust setae or fan setae. Basis endite distal margin with slender setae, without elongate setuate setae, medial margin with slender setae. Epipod lenticular and distally acute with rounded tip.

Pereiopod I ( Figs 3A View FIGURE 3 , 5D View FIGURE 5 ). Strongly propodosubchelate; distal articles similar in male and female. Merus dorsal projection shorter than half carpus length; with 2–4 setae (2 larger than others); length 0.93 carpus length. Carpus unequally triangular with distodorsal projection; width 1.6 length; with large robust seta on distoventral margin. Propodus unequal subtriangular with convex dorsal margin, proximal margin length 0.62 carpus length, with palm on ventral margin. Palm linear before inflection, with low obtuse projection at proximal inflection of palm, width 0.53 palm length, length 0.72 propodus length, margin without more projections distally. Palm margin with robust seta at inflection distinctly larger than more distal setae. Propodus ventral margin with 22–23 robust setae (♂, ♀), with 1–4 setae adjacent to proximal large seta, 9–15 smaller setae on posterior margin and 9 larger setae on anterior margin, smooth. Propodus ventral half with 4–5 simple setae proximally and 6 simple setae more distally along margin and 4–6 submarginal setae. Dactylus length 0.8 propodus length; ventral margin with row of 10–15 robust setae (approximately) (recumbent, in both sexes); lower claw absent.

Pereiopods II–VII ( Fig. 3B–G View FIGURE 3 ). Pereiopod II–IV carpus ventral margin with 10–11 robust setae, pereiopod V–VII carpus ventral margin 2–4 robust setae. Propodus ventral margin with 4–5 robust setae, distal margin with articular plate. Dactylus with accessory third claw. Pereiopod VII penes separate from coxa, paired at midline and projecting posteriorly, tapering to thin parallel-sided tubes.

Pleopod I of male ( Figs 4A View FIGURE 4 , 6A View FIGURE 6 ) rami covering pleopodal cavity and other pleopods, length 0.81 pleotelson length, and 1.2 pleopod II length, proximomedial margins without articulation, rami with single articulation, distal margin broadly rounded, from distal margin. Protopod not exposed in ventral view (covered by pleopod I).

Pleopod II of male ( Figs 4B View FIGURE 4 , 6B View FIGURE 6 ) protopod length at exopod insertion greater than half pleopod I length; distal lobe absent, exopod emerging from distal margin. Exopod with clearly flexible articulation, with intrinsic musculature; distal segment length greater than width, greater than proximal segment length; approximately linear, flattened in cross section; article distal margin 1 elongate setae. Pleopod II of male endopod ( Figs 4B View FIGURE 4 , 6D View FIGURE 6 ). Appendix masculina length 0.91 protopod length, greater than exopod length; distal stylet length 0.33 appendix masculina length; tip width distinctly less than basal article width; nearly linear, without distinct curve, tapering but not acute, with cuticular ridges. Appendix masculina sperm guide tubular, enclosed at least partially, tube length short, distinctly less than distance from proximal opening to distal tip; proximal opening length large, substantially more than distal article width, elongate trough with proximal rounded opening; distal opening subdistally with medially directed open trough (with small angular medial plate). Pleopod II of female ( Fig. 4G View FIGURE 4 ). Length near width, 1.1 width; operculum lateral margin smoothly convex without inflection until distal margin, posterior margin broadly concave with rounded corners distolaterally.

Pleopod III, IV and V ( Fig. 4C–E View FIGURE 4 ). Exopod distally rounded.

Uropod ( Figs 4F View FIGURE 4 , 5C View FIGURE 5 ). Length 0.68–0.9 pleotelson length (female longest). Protopod length 0.87–0.9 endopod length, 2.6 width, proximal width less than distal width. Endopod length 1.2–1.6 exopod length. Exopod length 0.8 protopod length. Both rami with scattered slender setae in both margins and with distal group.

Distribution. Chile, Osorno province, Los Lagos region.

Habitat. Springs associated with riverine groundwater.

Remarks. Wiyufiloides osornoensis gen. & sp. nov. is endemic to a small area of the Rahue river basin, a sub-basin of the river Bueno, in Los Lagos Region, southern Chile. This species was only found in some springs restricted to the central depression in the Osorno province. One of these sites is subject to intensive agriculture and cattle breeding, and the type locality is located in middle of Osorno city. The spring, however, was drained and destroyed some years ago for construction a short road. The species may still persist in the aquifer but this is unknown.

The animals inhabit phreatic groundwater that flows through coarse sand and gravel, and have been observed only among the accumulated sediments in the upwelling area and excavating a few centimeters down, where several (up to nine) specimens can be found at the same time.

Until now, the only other groundwater crustacean known to inhabit the same locality with Wiyufiloides osornoensis gen. & sp. nov. is the bogidiellid amphipod Patagongidiella wefkoi Pérez-Schultheiss, 2013 .