Grandidierella phetraensis, Wongkamhaeng, Koraon, Coleman, Charles Oliver & Pholpunthin, Pornsilp, 2013

Wongkamhaeng, Koraon, Coleman, Charles Oliver & Pholpunthin, Pornsilp, 2013, Three new species from the Aoridae and Maeridae (Crustacea, Amphipoda) from Thai Waters, Zootaxa 3693 (4), pp. 503-533 : 512-519

Grandidierella phetraensis sp. nov.

( Figs 8–13 )

Type material. Holotype, male, 7.2 mm, PSUZC-CR-0268, sandy beach of Satun province 6°50'7"N 99°45'20"E Thailand, 27 November 2011, 2 m, Rodcharoen, E. Allotype: female, 7.1 mm, PSUZC-CR-0269, same station data. Dissected appendages were kept in six semi-permanent slides mounted on glycerol. Paratype, 4 males and 2 females, ZMB 27976 same station data.

Additional material. PSUZC-CR-275 5 males and 2 females, same station data.

Type locality. Phetra Beach Satun Province, Thailand, Andaman Sea.

Etymology. This species is named after the type locality.

Description. Based on holotype male, 7.2 mm, PSUZC-CR-0268.

Head subequal in length to first 2 pereonites. Antenna 1 longer than antenna 2, peduncular article 1–3 ratio 7:8:2; flagellum longer than peduncle with 14 articles, each article with short setae distally and last 8 article additionally with aesthetascs; accessory flagellum uni-articulate. Antenna 2 peduncle stout, inner margin of article 3 with a robust seta; article 5 shorter than 4; flagellum short, with 4 articles, all article setiferous with a pair of curved robust setae. Mandible, both incisors 4-dentate; lacinia mobilis armed with 3 teeth on left and 4 teeth on right side; molar armed a single seta; palp article 1–3 subequal.

Pereon lacking sternal processes. Gnathopod 1 coxal plate suboval, unproduced; basis stout, 1.8 × as long as broad; carpus 1.5 times as long as broad, posterodistal corner produced into a tooth, inner face oblique with two smaller teeth, posterior margin smooth and setose; propodus longer than dactylus in length, posterior margin proximally excavate, distally expanded; dactylus curved, distal end concave with 3 robust setae. Gnathopod 2 subchelate; coxa posteroventrally produced into a tooth; basis slender, not expanded distally; carpus longer than propodus, 2.2 × as long as wide, posterior margin crenulated, bearing pectinate setae; propodus palmar margin transverse, with fine setae and 2 defining bifid robust setae; dactylus slightly longer than palmar margin, inner margin with accessory tooth and 3 robust setae. Pereopod 3 and 4 similar, coxal plate slightly posteroventrally produced; basis slender, sparsely setose; propodus narrow, both margin bearing setae; dactylus long and slender, shorter than propodus. Pereopod 5–7 length ratios 5: 8:11, pereopod 7 basis with plumose setae on posterior margin.

Pleopod. Uropod 1 peduncle longer than both rami, fringed with robust setae, peduncular apex bearing a posteroventral process; rami lined with a row of robust setae, distal bearing several robust setae. Uropod 2 peduncle shorter than both rami with two apical robust setae, rami beset with robust setae; outer ramus longer than inner one. Uropod 3 uniramous, peduncle expanded, much shorter than ramus with a distal robust seta; ramus with short second article, apex with 3 long setae. Telson subtrapezoidal, ending in two pointed telsonic angles providing a long robust seta plus one short seta on each lobe.

Female - sexually dimorphic characters. (Based on allotype female, 7.1 mm, PSUZC-CR-0269).

Pereon. Gnathopod 1 coxa not produced; basis more slender, 2.8 × as long as broad; carpus trapezoid, about 2.4 × as long as broad, posterior margin setose; propodus oval, shorter than carpus, palm oblique and defined by a robust seta, palmar margin with short setules, distal end sparsely covered with setae; dactylus curved with 4 short stout robust setae on inner marginal. Gnathopod 2 similar to that of male, slightly smaller than gnathopod 1; basis slender; carpus about 1.8 × as long as wide; propodus with 3 bifid robust setae on posterior margin; dactylus curved, grasping margin with fine setules and 4 short stout robust setae.

Remarks. This species resembles Grandidierella trispinosa Bano & Kazmi, 2010 from India and Grandidierella bonnieroides (Stephensen 1948) which is distributed in the Atlantic and the Indian Ocean in the following: gnathopod 1 basis robust, less than 2 × as long as broad; coxa 2 produced posteriorly into a tooth; uropod 3 peduncle expanded, rami with 2 articles, second article rudimentary. However, the current species differs from both species in not having any sternal processes (vs. with sternal processes in both species), male gnathopod 1 without posteromarginal tooth (vs. bearing posteromarginal tooth) and the ratio of mandibular palp articles is 1:1:1 while that of G. bonnieroides is 5:8:8 and that of G. trispinosa is 2:3:3.

Figures

FIGURE 8. Grandidierella phetraensis sp. nov., holotype, male (PSUZC-CR- 0268), 7.2 mm, sandy beach of Satun province, Andaman Sea. Scale bars for A 1 represent 0.5 mm, A 2 0.2 mm, UL and LL 0.1 mm.

FIGURE 9. Grandidierella phetraensis sp. nov., holotype, male, (PSUZC-CR- 0268), 7.2 mm, sandy beach of Satun province, Andaman Sea. All scale bars represent 0.1 mm.

FIGURE 10. Grandidierella phetraensis sp. nov., holotype, male (PSUZC-CR- 0268), 7.2 mm. sandy beach of Satun province, Andaman Sea. All scale bars represent 0.2 mm.

FIGURE 11. Grandidierella phetraensis sp. nov., holotype, male (PSUZC-CR- 0268), 7.2 mm, sandy beach of Satun province, Andaman Sea. Scale bar for T represents 0.1 mm, remaining represent 0.2 mm.

FIGURE 12. Grandidierella phetraensis sp. nov., holotype, male (PSUZC-CR- 0268), 7.2 mm. sandy beach of Satun province, Andaman Sea. Scale bars for P 6 and P 7 represent 0.5 mm, U 1 and U 2 represent 0.2 mm, U 3 represents 0.1 mm.

FIGURE 13. Grandidierella phetraensis sp. nov., alllotype, female (PSUZC-CR- 0269), 7.1 mm, sandy beach of Satun province, Andaman Sea. Scale bar for A 1 represents 0.5 mm, remaining represent 0.2 mm.