Austinixa roblesi Theil & Felder 2020, sp. nov.
Creators: name: Theil, Emma Palacios
name: Felder, Darryl L.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Pinnotheridae
Austinixa
Austinixa roblesi

description: Austinixa roblesi sp. nov.
(Figs 8, 9, 12 D–F)
urn:lsid:zoobank.org:act: 5AEFF4CA-FD14-4C49-92E8-F13E43C4DE99
Austinixa sp. 3. — Palacios Theil et al. 2016: 4 (table 2), 9 (fig. 1), 10 (fig. 2), 16 (fig. 5b); present paper: Figs 1–3, Tables 1, 2.
Material examined. Holotype: USNM 1558341, adult male, cw 9.9 cl 3.9 mm, Dangriga, Belize, 16°58.89’ N 88° 13.55’ W, beach next to Pelican Beach Resort, intertidal zone, yabby pump, 16 Dec 2002, coll. D.L.F., R. Lemaitre, and R. Robles.
Paratypes: USNM 1558340, 4 adult males, cw 6.8–9.0 cl 3.0– 3.5 mm, 4 ovigerous females, cw 8.2–9.8 cl 3.7–4.2 mm, adult female, cw 7.0 cl 3.2 mm, collection data same as holotype; USNM 1558342, adult female, cw 6.2 cl 3.1 mm, Boca del Drago, Isla Colón, Bocas del Toro, Panama, 09° 24.79’ N 82° 19.92’ W, intertidal, yabby pump, 6 Aug 2011, coll. D.L.F., F. Mantelatto, E.P.T. et al.; ULLZ 5518, 2 ovigerous females, cw 9.7 and 9.2 cl 4.3 and 4.3 mm, Dangriga, Belize, collection data same as holotype, DNA vouchers; ULLZ 12114, adult male, cw 8.6 cl 3.5 mm, ovigerous female, cw 11 cl 4.8 mm, adult female, cw 6.8 cl 3.5 mm, Dangriga, Belize, collection data same as holotype, photograph vouchers; ULLZ 12115, 2 adult males, cw 9.3 and 9.4 cl 3.7 and 3.8 mm, ovigerous female, cw 9.4 cl 3.8 mm, Dangriga, Belize, collection data same as holotype; ULLZ 13143, 10 males, cw 4.9–9.5 cl 1.9–3.9 mm, 7 ovigerous females, cw 7.2–10.4 cl 3.1–4.6 mm, 5 adult females, cw 5.3–6.6 cl 2.4–3.2 mm, juvenile, cw 3.0 cl 1.6 mm, Dangriga, Belize, collection data same as holotype; ULLZ 13335, ovigerous female, cw 7.8 cl 3.2 mm, collection data same as paratype USNM 1558342, DNA voucher, photograph voucher; ULLZ 13733, adult male, cw 6.2 cl 2.8 mm, Boca del Drago, Isla Colón, Bocas del Toro, Panama, 09° 24.79’ N 82° 19.92’ W, intertidal, yabby pump, 10 Aug 2011, coll. D.L.F., F. Mantelatto, E.P.T. et al.; ULLZ 15337, adult male, cw 6.5 cl 2.9 mm, adult female, cw 6.6 cl 3.0 mm, seagrass flat near Bucaneer Resort, Isla Carenero, Bocas del Toro, Panama, 9° 20.45’N 82° 13.87’ W, 14 Nov 2006, coll. A. Anker et al..
Additional material: UF 18893, male, cw 6.4 cl 2.9 mm; UF 18912, ovigerous female, cw 7.5 cl 3.2 mm, female, cw 7.6 cl 3.1 mm, UF 18926, ovigerous female, cw 9.4 cl 3.8 mm, DNA voucher; UF 18939, female, cw 6.0 cl 2.3 mm, intertidal zone, sand flat with sparse seagrass, Playa de las Estrellas, Bocas del Toro, Panama, 9° 25.06’ N 82° 19.46’ W, yabby pump, 28 Oct 2005, coll. A. Anker; UF 18905, ovigerous female, cw 8.1 cl 3.7 mm, fine sand close to seagrass, Isla Grande, Panama, 09° 37.68’ N 79° 34.14’ W, 7 Oct 2005, coll. A. Anker; UF 18932, ovigerous female, cw 8.3 cl 3.7 mm, same location as previous, 11 Jun 2006, coll. A. Anker; UF 18928, male, cw 6.9 cl 2.8 mm; UF 18945, male, cw 5.2 cl 2.3 mm, UF 18943, female, cw 6.8 cl 2.8 mm, DNA voucher, 5 Oct 2005, other collection data same as previous.
Size. Males cw 4.9–9.9 mm (n = 23), ovigerous females cw 7.2–11 mm (n = 20), females cw 5.3–7.0 mm (n = 12), one juvenile cw 3.0 mm.
Distribution. Known from Dangriga (Belize), Bocas del Toro and Isla Grande (Panama).
Diagnosis. Carapace with each branchial region transversed by ridge, nearly reaching orbit, turning laterally sharply towards posterior; male carapace with dorsal setal patch on posterior third, anterior to cardiac ridge; P4 propodus opposable margin bicarinate; P4 merus with setose depression on posterior half of distal end of dorsal surface, depression not continuing into posterior surface.
Description. Carapace smooth, 2.0–2.6 times wider than long, with sharp cardiac crest extending entirely across cardiac region, above posterior margin; branchial regions each crossed by sharp ridge, nearly reaching orbit and turning laterally sharply towards posterior end, nearly reaching posterolateral margin; mesolateral margins tuberculate; male carapace with a setal patch on posterior half, anterior to cardiac ridge. Antennae with 9 articles, third longest (Figs 8A, B, 9 A–C). Third maxilliped ischiomerus indistinguishably fused, elongate; three-segmented palp, nearly as long as ischiomerus; carpus very short; dactylus and propodus elongate, margins with long setae, dactylus inserted near base of propodus, reaching clearly beyond end of propodus. Exopod with angle on non-opposable margin (Fig. 8C). Chelipeds of male and female similar, with exception male chelipeds being slightly stouter. Chela strong, stout, smooth with the exception of a line of setae on internal surface, near and subparallel to inferior margin, extending from proximal palm end reaching distal end and continuing up to proximal third to half of fixed finger; distal palm surface with excavate region at dactylus base, region delimited by serrated edges and 2 large triangular teeth, palm superior margin with ridge extending end to end, and continuing on dactylus exterior margin, nearly reaching dactylus tip, palm ventral margin blunt; fixed finger straight, about third to half as long as palm, cutting edge serrated, triangular tooth median, gape very setose; dactylus strongly deflexed, unarmed, cutting edge serrated (Figs 8D, 9D, E). P2– P5 long and slender, relative lengths P4> P3> P2> P5, margins setose, but not densely, dactyli slender; P2 and P3 dactyli slightly curved, P4 dactylus straight, P5 dactylus straight, with exception of deflected tip; P4 and P5 dactyli with anterior and posterior ridges; P4 merus with depression on posterior half of dorsal surface, as long as one third of merus, depression separated from posterior surface of merus and covered with patch of short setae, posterior (opposable) surface of merus also covered with short setae; P4 propodus posterior surface bicarinate (Fig. 8A, E, F). Male pleon with 6 somites plus telson, none fused, first somite subtrapezoidal, somites 2–6 subrectangular, slightly decreasing in width, telson quasi semiellipsoid, about as long as sixth somite (Fig. 8G). Female pleon subcircular with 6 somites plus telson, none fused, somite 4 widest, somites 3–6 and telson of about same length, somites 1 and 2 each of about half the length of somite 3; telson subtriangular, apex rounded (Fig. 9F). Male first gonopod as illustrated (Fig. 8H, I).
Etymology. The species name honors Rafael Robles, a valued friend and colleague who helped collect the first specimens of this species and has extensively contributed to much of our other work with his comments, company, and always welcomed humor.
Remarks. Austinixa roblesi sp. nov. resembles A. chacei and A. behreae in the presence of branchial ridges that turn sharply at the lateral edges and continue toward the posterior region of the carapace, unlike for other species of Austinixa with those kinds of ridges, where the branchial ridges simply continue laterally to the lateral margins, or fall short of margins. Austinixa roblesi sp. nov. differs from A. chacei and A. behreae in the presence of a setal patch on the posterior part of the male carapace. In addition, A. roblesi sp. nov. can be distinguished from A. chacei by the posterior margin of the P4 propodus, which is bicarinate in A. roblesi sp. nov. but unicarinate in A. chacei. Austinixa roblesi sp. nov. resembles A. aidae in the presence of a setal patch on the posterior part of the male carapace, but A. aidae lacks branchial ridges. Austinixa roblesi sp. nov. can be distinguished from congeners by the presence of a characteristic depression on the posterior surface of P4 merus. Austinixa leptodactyla also bears a depression on the P4 merus. Unfortunately, no specimens of A. leptodactyla were available for examination, although when comparing the description given by Coelho (1997) of that depression, it is different than the one observed in A. roblesi sp. nov. When describing the third ambulatory leg, Coelho (1997: 179) writes: “... com mero inflado; uma depressão na superficie posterior, continuando dorsalmente, onde os quintos pereiópodos se encaixam com certa liberdade. ” (... with merus swollen; a depression on posterior or posterodorsal surface, continuing dorsally, where the fifth pereopods fit somewhat freely). Although Coelho (1997) does not specify it, we assume the depression he describes occupies the proximal end of the posterior surface of the P4 merus, in order for the fifth pereopods to “fit freely”. The depression in A. roblesi sp. nov. is in the distal half of the merus, beyond reach of the P5 dactylus, which cannot fit into it (Fig. 8E).
description: Published as part of Theil, Emma Palacios & Felder, Darryl L., 2020, Phylogeny of the genus Austinixa Heard & Manning, 1997, inferred from mitochondrial and nuclear molecular markers, with descriptions of three new species and redescription of Austinixa felipensis (Glassell, 1935) (Decapoda: Brachyura: Pinnotheridae), pp. 101-134 in Zootaxa 4778 (1) on pages 123-126, DOI: 10.11646/zootaxa.4778.1.4, http://zenodo.org/record/3823672