Dulichiella pattaniensis, Wongkamhaeng, Koraon, Pattaratumrong, Manasawan Saengsakda & Puttapreecha, Ratchanee, 2014

Wongkamhaeng, Koraon, Pattaratumrong, Manasawan Saengsakda & Puttapreecha, Ratchanee, 2014, Melitid amphipods from the Gulf of Thailand, with a description of Dulichiella pattaniensis, a new species, ZooKeys 408, pp. 1-18 : 3-4

Dulichiella pattaniensis sp. n.

Type material.

Holotype. ♂, THAILAND, Lower Gulf of Thailand, Pattani Bay (6°51'55"N, 101°10'7"E), artificial reef (associated with coral settlement plate), 1 September 2010, Puttapreecha, R., PSUZC-CR-0192. Allotypes, ♀ collected with holotype; PSUZC-CR-0193; Paratype, collected with holotype (PSUZC-CR-0194 (5♂; 5♀)).

Description.

Based on male holotype. Body length 6.3 mm (from tip of rostrum to apex of telson). Body compressed, subcylindrical. Head, lateral cephalic lobe truncate, anteroventral corner with setae, eyes round. Antenna 1, setiferous, ratios of peduncular articles 1-3 4:5:1; peduncular article 1 with 3 ventromarginal robust setea and distoventral setae; accessory flagellum with 5 articles, last article reduced; primary flagellum 16-articulate (possibly regenerating in this specimen), flagellum can be 25-articulate (observed from additional material). Antenna 2, Antenna 2 setiferous, peduncular article 2 cone gland not reaching end of article 3; article 5 subequal to 4, flagellum 9-articulate.

Upper lip, (labrum) distally rounded. Lower lip, inner lobes well developed, pubescent. Mandible, both similar, left incisor 3 dentates, right incisor 4 dentate; left and right lacinia mobilis armed with 3 and 4 dentates respectively; palp slender with marginal setae, article 1 smooth, article 3 slightly longer than article 2. Maxilla 1, inner plate narrow with 2 apical plumose setae; outer plate with 8 apical serrate robust setae; palp 2-articulate, article 1 with 3 distal setae, article 2 with 4 apical robust setae and 4 apical setae. Maxilla 2, inner plate with mediofacial row of 29 setae and 14 apical plumose setae; outer plate broader than inner plate, distally setose. Maxilliped, inner plate borad, with 6 plumose marginal setae; outer plate margin with 11 conate robust setae, terminal with 4 plumose setae; palp 4-articulate, article 2-3 with marginal setae, article 4 tapering with fine marginal setae.

Pereon. Gnathopod 1 subchelate, smaller than gnathopod 2; coxa anterodistal corner not produced, posteroventral corner notch present, anterior margin straight; length ratio of articles from basis to dactylus 10: 3:4:7:5: 3; basis slender; merus–propodus setose; palm slightly convex, defined by posterodistal corner, without posterodistal robust setae. Gnathopod 2 sexually dimorphic; left and right gnathopods unequal in size; coxa posteroventral corner notch present; (larger) length ratio of article from basis to dactylus 8:1:3:1:10:11; propodus distolateral corner crown with 4 rounded spines, palm straight, posterodistal corner produced, upturned, fit with dactylus; dactylus apically blunt; (smaller) subchelate; length ratio of article from basis to dactylus 9:3:4:6:6:4; merus with sharp posteroventral spine; carpus subequal to propodus; palm straight, without posteroventral spine. Pereopod 3-4 alike. Pereopod 5 basis posterior margin straight, posteroventral corner rounded; carpus and propodus sparsely setose; dactylus unguis anterior margin with accessory spines. Pereopod 6-7 alike, basis, merus, carpus, propodus with long marginal setae. Pereopod 6 basis posterior margin straight, minutely castelloserrate; dactylus unguis anterior margin with accessory spines. Pereopod 7 basis posterior margin straight, with posterior margin minutely castelloserrate, posteroventral corner; dactylus unguis anterior margin with accessory spines.

Pleon. Pleonite/urosomite dorsal spine formula (7-7-7-5-6-2). Pleonites 1-3 with dorsal setae. Epimera 1-3 posteroventral margin without spines above posteroventral corner. Epimeron 3 posterior margin smooth, posteroventral corner with strongly produced acute. Urosomite 1 with spine at midline, no medial gape. Urosomite 2 with dorsal setae. Urosomite 3 with dorsal setae, with 2 dorsal spines. Uropod 3 inner ramus scale-like, much shorter than outer ramus; outer ramus much longer (more than 2 × length) than peduncle, 2-articulate. Telson with dorsal robust setae.

Female. (sexually dimorphic characters). Length, 7.4 mm. Gnathopod 1 coxa 4 anterodistal corner not produced, posteroventral corner notch present, anterior margin excavated. Gnathopod 2 equal, coxa subrectangular, palm crenulated, oblique with setae on margins. Pereopod 7 basis expanded, posterior margin slightly convex.

Etymology.

This species is named after the type locality.

Remarks.

Dulichiella pattaniensis sp. n., with pleonite/urosome formular of 7-7-7-5-6-2 has only Dulichiella cotesi , Dulichiella oahu , Dulichiella pacifica and Dulichiella tulear that share this characters. This new species can be distinguished from Dulichiella cotesi , Dulichiella oahu and Dulichiella tulear by having male gnathopod 2 (large) with 4 spines on distolateral crown while those three species have 3 spines. Dulichiella pattaniensis differs from Dulichiella pacifica in the following: the male large gnathopod 2 has a fourth spine on its distolateral crown that is not well developed vs. its well-developed fourth set of spines. The male gnathopod 1 has carpus longer than its propodus vs. a carpus subequal to its propodus. Pereopods 3-4 have a dactyli with 2 accessory spines vs. 3-4 dactyli with 1 accessory spine.

The new species also has four spines on the distolateral crown of the male gnathopod 2. Only 7 species, Dulichiella appendiculata , Dulichiella cuvettensis , Dulichiella celestun , Dulichiella fresnellii , Dulichiella guinea , Dulichiella lecroyae , Dulichiella pacifica and Dulichiella takedai share this distinct character. Dulichiella pattaniensis can be distinguished from amphipods by having pleonite/urosome formular of 7-7-7-5-6-2 while Dulichiella appendiculata , Dulichiella cuvettensis , Dulichiella fresnellii , Dulichiella lecroye and Dulichiella pacifica pleonite/urosome formula 7-7-7-5-4-2, Dulichiella guinea 9-9-7-5-4-2 and Dulichiella celestun 9-9-9-5-6-2. Moreover, Dulichiella pattaniensis differs from Dulichiella cuvettensis , Dulichiella guinea and Dulichiella lecroyae by having 2 accessory spines on pereopods 3-4 dactyli vs. 1 accessory spine. A summary of these distinguishing characters are given in Table 1.