Atyoida pilipes (Newport 1847)

(Figure 3)

Atya pilipes Newport, 1847: 160 [type locality: “Apia, Upolu, New Zealand ” (corrected to “Apia, Upolu, Navigator or Samoan group” by Dana, 1852: 533].

Atyoida pilipes - Chace, 1983: fig. 3 page 13.

Atyoida pilipes - Keith et al. 2002: 38-39 (partim).

Atyoida pilipes - Keith and Marquet, 2011: 34-35.

Atyoida pilipes - Mary et al. 2006: 33.

Atyoida pilipes - Keith et al. 2010: 32-33 (partim).

Atyoida pilipes - Keith et al. 2013: 72-73 (partim).

Not Atya serrata - not Ortmania alluaudi. Adamson, 1939: 36.

Not Atya serrata - Edmondson, 1935: 14, fig.i.

Material examined

Polynesian material: SAMOA. UPOLU: Tuafaleloa river, 1♂, cl 5mm (MNHN-IU-2018-3023; DNA: CA1950), 1♂, cl 4.8mm (MNHN-IU-2019-242; DNA: CA1949), 1♀ ovig., 7.9mm (MNHN-IU-2019-497; DNA: CA2363) and 1♀ ovig., cl 8.8mm (MNHN-IU-2019-155), 13°53.774’S, 171°40.026’W, July 08, 2014, 250m a.s.l., coll. P. Gerbeaux. – Falefa river, 1juv., cl 3.2mm, (MNHN-IU-2019-162; DNA: CA2362), 1♂, cl 4.6mm (MNHN-IU-2018- 3213; DNA: CA2367), 1♂, cl 5.2mm (MNHN-IU- 2018-2979; DNA: CA2364), 1♂, cl 5.2mm (MNHN-IU- 2018- 2976; DNA: CA2366), 1♀ ovig., cl 8.8mm (MNHN-IU-2019-499; DNA: CA2361), 13°54.728’S, 171°36.137’W, July 10, 2014. 53m a.s.l., coll. P. Gerbeaux. SAVAI: Faleata river, 1juv., cl 4,6mm (MNHN-IU- 2018-2952; DNA: CA2370), 1♂, cl 5.5mm (MNHN-IU- 2018-2948; DNA: CA2369), 1♀ ovig., cl 7.8mm (MNHN-IU-2019-239; DNA: CA2368), and 1♀ ovig., cl 7.9mm (MNHN-IU-2019-495; DNA: CA2365), 13°43.761’S, 172°19.548’W, July 12, 2014, 195m a.s.l., coll. P. Gerbeaux. – Seugagogo river, 1♂, cl 4.9mm (MNHN-IU-2019-489; DNA: CA2371), 13°40.313’S, 17219.548’W, August 09, 2013, 773m a.s.l., coll.? WALLIS AND FUTUNA TERRITORY. FUTUNA: Vainifao river, 1juv., cl 4.3mm (MNHN-Na-15750; DNA: CA2135), 1juv., cl 4.7mm (MNHN-Na-15750; DNA: CA2136), and 1♂, cl 4.5mm (MNHN-IU- 2018-2983; DNA: CA2377), 14°17.738’S, 178°08.423’W, October 12, 2004, 150m a.s.l., coll. P. Keith, G. Marquet, N. Mary. FRENCH POLYNESIA. HIVA OA: Taooa river, 1♂, cl 4.6mm (MNHN-IU- 2018-2988; DNA: CA2069), and 1♀ ovig., cl 5.5mm (MNHN-IU- 2018-2989; DNA: CA2068), 09°49.750’S, 139°04.419’W, October 09, 2017, 220m a.s.l., coll. E. Feunteun, P. Keith, G. Marquet. NUKU HIVA: Taipivai river, 1♂, cl 4.9mm (MNHN-IU- 2018-2975; DNA: CA2385), 1♂, cl 5mm (MNHN-IU-2018-3003; DNA: CA2386), 1♂, cl 5.6mm (MNHN-IU- 2018-2987; DNA: CA2374), and 1♀, cl 8.3mm (MNHN-IU- 2018-2984; DNA: CA2375), 08°51.126’S, 140°06.066’S, 140°06.066’W, October 18, 2017, 130m a.s.l., coll. E. Feunteun, P. Keith, G. Marquet. UA POU: Unnamed rivulet, 1 juv., cl 4.0mm (MNHN-IU- 2018-2982; DNA: CACA2388), 1 juv., cl 4,9mm (MNHN-IU- 2018-2993; DNA: CA2389), 1 juv., cl 4.7mm (MNHN-IU-2019-156; DNA: CA2391), 1 juv., cl 4.9mm (MNHN-IU- 2018-2949; DNA: CA2395), 1 juv., cl 4.8mm (MNHN-IU-2019-159; DNA: CA2072), 1♂, cl 4.2mm (MNHN-IU- 2018-2953; DNA: CA2393), 1♂, cl 5.1mm (MNHN-IU-2018-3017; DNA: CA2392), 1♂, cl 5.5mm (MNHN-IU-2019-477; DNA: CA2390), 1♂., cl, 4.9 mm (MNHN-IU-2019-166), 1♀, cl 5.7mm (MNHN-IU- 2018-2985; DNA: CA2394), 1♀, cl 6.2 mm (MNHN-IU-2018-3274; DNA: CA2396), 1♀, cl 6.8mm (MNHN-IU-2018-3275; DNA: CA2397), 1♀, cl 9.1mm (MNHN-IU-2018-3276; DNA: CA2398), 09°25.452’S, 140°03.409’W, October 14, 2017, 149m a.s.l., Coll. E. Feunteun, P. Keith, G. Marquet.

Other material: FIJI. TAVEUNI: Lavena river, 1♂, cl 5.2mm (MNHN-IU-2018-3277; DNA: CA1962), and 1♀, cl 5.2mm (MNHN-IU-2018-3278; DNA: CA1961), 16°52.164’S, 179°54.333’W, February 25, 2013, altitude 91m a.s.l., coll. P. Gerbeaux, P. Keith, G. Marquet. VANUATU. TANNA: Lembau river, 1♂, cl 5.6mm (MNHN-IU-2018- 3279; DNA:CA1952), and 1♀, cl 6.3mm (MNHN-IU-2018-3280; DNA: CA1951), 19°23.005’S, 169°18.852’E, June 29, 2015, 260m a.s.l., coll. D. Kalfatak, C. Lord, G. Segura. ANEITYUM: Inugé river, 1♂, cl 4.8mm (MNHN-IU-2018-3281; DNA: CA1956), 1♂, cl 4.8mm (MNHN-IU-2018-3282; DNA: CA1955), 20°12.458’S, 169°46.993’E, June 25, 2015,219m a.s.l., coll. D. Kalfatak, C. Lord, G. Segura.

Description

Cephalothorax. Rostrum short (Fig. 3n), 0.2-0.4 of cl, reaching near to or slightly beyond end of basal segment of antennular peduncle, with dorsal margin convex, apex slightly ventrally, ventral margin unarmed; Antennal spine fused with inferior orbit angle, acute; pterygostomian margin acute.

Eyes well developed. Antennular peduncle stout, 0.43 (♀) - 0.63 (♂) times as long as carapace; basal segment shorter than half length of antennular peduncle, second segment longer than third segment. Stylocerite reaching 0.86-0.93 length of the basal segment of antennular peduncle.

Pereiopods. Epipods on first 4 pereiopods. P1 and P2 similar in size and shape. Chelae dimorphic, caridinoid in shape in males and atyoid in females. ♂ P1 (Fig. 3b) chela about 1.7-4.7 times as long as wide, movable finger 3.5- 6.1 times as long as wide1.8-12.0 times length of palm; ♀ P1 (Fig. 3a) chela 1.9-4.2 times as long as wide, dactylus 3.5-5.3 times as long as wide, with tufts of long setae distally, carpus excavated strongly anteriorly, 0.9-1.4 times as long as wide. ♂ P2 chela 2.1-4.0 times as long as wide: movable finger 3.6-5.3 times as long as wide, 1.6-11.5 times length of palm; ♀ P2 (Fig. 3c) chela 2.1-4.3 times as long as wide, dactylus 3.6-5.2 times as long as wide, with tufts of long setae distally, P2 carpus excavated strongly anteriorly, 1.0-1.6 times as long as wide. P3 (Fig. 3d) with row of setae on outer surface of each joint, very short dactylus (Fig. 3f) ending in a strong claw, 1.7-3.7 times as long as wide (terminal spine included) with 3-5 spines on flexor margin in addition to the terminal spine; propodus 3.9-7.5 times as long as wide, 2.2-3.7 times as long as dactylus. P5 (Fig. 3e) with setae only present on merus; dactylus (Fig. 3g) short 2.1-5.1 as long as wide with 4-14 spines on flexor margin; propodus 6.0-10.4 times as long as wide, 2.9-4.8 times as long as dactylus.

Abdomen. Sixth abdominal somite 0.37 times of carapace, 1.1 time as long as fifth somite, 0.84 as long as telson.

Telson (Fig. 3j) 2.3-3.1 times as long as wide, with one to five pairs of dorsal spinules, often not in pairs, one pair of dorsolateral spinules near dorsal end; posterior margin rounded with 4 to 9 plumose intermediate setae distinctly longer than lateral ones.

Pl1 (Fig. 3k): Endopod of male subtriangular, 2.7 times as long as wide, reaching 0.57 times of endopod, with a distinct appendix interna near distal end of endopod.

Pl2 (Fig. 3l): Appendix masculina of male reaching 0.57 times length of endopod, inner and distal surface densely lined with long spines; appendix interna at basal 0.36 times length of appendix masculina, extending to distal 0.34 length of appendix interna.

Preanal carina triangular (Fig. 3h) without spine.

Uropodal diaeresis (Fig. 3i) with 15-22 spinules.

Eggs (Fig. 3m): developed (visible eyes): 0.35-0.42 × 0.56-0.68mm; undeveloped: 0.32-0.36 × 0.49-0.58mm.

Habitat

In Nuku-Hiva (Marquesas islands), large males and females of A. pilipes are present, although in small numbers, at all altitudes; females, small males and ovigerous females are more abundant below 100m. A. pilipes, particularly females, occur mainly in water with high velocities and on coarse substrata (less sands, gravels and pebbles, more rocks). On contrary, males were indifferent with water velocity and their abundance did not depend on rocks. Large males appeared more frequent where the riverbeds have less vegetation, while small males were more frequent in shallow habitats (see Fossati & Keith, 2002). This habitat difference between males and females is to put in relation with their chelae. Indeed, females with their atyoid chelae are adapted for filter-feeding and males with their caridinoid chelae, to sweeping. Thereby females are localised in the currents and on the rocks and males in vegetation.

Colour pattern

The back (Fig. 5) is orange-yellow as well as the antennular peduncle, telson and uropods. The flanks are whitish ornamented with numerous blue-black patterns of various shapes.

Distribution

This species (Fig. 7) occurs in Vanuatu (Tanna, Aneityum), Fiji, Samoa, Futuna and Marquesas archipelago.

Remarks

As the type locality of A. pilipes, described by Newport, is Apia, Upolu Island, capital city of Samoa, we affirm that all specimens genetically and morphologically similar to those of Upolu belong to this species. The description of one specimen of A. pilipes by Newport is very succinct and therefore not informative: “Body smooth, rostrum simple, triangular, very short with a slight median ridge, fourth and five pairs of legs nearly equal, femoral joint with an oblique sulcus on the external surface, fringed with a margin of dense fine hairs”.