Paragrandidierella Ariyama, 2002

Ariyama, Hiroyuki, 2013, Reinstatement of Paragrandidierella (Crustacea: Amphipoda: Aoridae) from Japan, with the Description of a New Species, Species Diversity 18, pp. 223-235 : 223-224

Paragrandidierella Ariyama, 2002

[Japanese name: Himedorosokoebi-zoku]

Paragrandidierella Ariyama, 2002: 155 .

Grandidierella: Ren 2006: 368 (in part).

Emended diagnosis. Body subcylindrical, somewhat compressed dorsoventrally, smooth. Rostrum indistinct. All pereon segments lacking ventral process. Urosomites free, short. Antenna 1 slender, peduncular article 3 much shorter than article 1, accessory flagellum vestigial; antenna 2 peduncle rather stout. Upper lip entire. Mandibular palp slender, articles 2 and 3 longer than article 1, article 3 rectolinear; incisor small, with 3–4 cusps, lacinia mobilis with 2–3 cusps, accessory blades 4 in left mandible, 5 in right. Lower lip with long mandibular process; apical margin of inner lobe with minute projection. Inner plate of maxilla 1 indistinct; outer plate pointed apically, with 3 stout robust setae and 5–7 normal setae distally; palp 2-articulate, slen- der, curved medially, with 3 short setae at tip. Inner plate of maxilla 2 elongate-triangular, margin with row of setae; apical margin of outer plate truncate, bearing many setae. Inner plate of maxilliped lacking distal robust setae; outer plate broad, exceeding apex of palp article 2, with 6 marginal robust setae; palp consisting of 4 articles, article 3 bearing robust seta dorsodistally, article 4 with claw. Coxae small, almost disjunct, coxa 5 widest; coxal gills present on pereopods 2–6; oostegites of female narrow, present on pereopods 2–5. Male gnathopod 1 enlarged, carpochelate; basis wide, ischium short, merus triangular, carpus broad, with tooth on posterodistal corner, propodus smaller than carpus. Female gnathopod 1 smaller than that of male, simple; carpus longer than propodus, propodus with 3–4 robust setae on posterior margin. Gnathopod 2 of both sexes smaller than gnathopod 1, simple; carpus longer than propodus, propodus with 2 robust setae each on posterodistal corner and posterior margin, dactylus short. Pereopods 3 and 4 similar to each other, slender; bases and propodi elongate, dactyli narrow. Pereopods 5–7 progressively increasing in length, pereopod 7 more than twice as long as pereopod 5; posteroproximal corner of basis of pereopods 5 and 6 produced, posterior margin of both coxae bearing plumose setae. Epimeral plates rounded posteroventrally. Pleopods short, peduncles each with a few plumose setae and 2 coupling hooks, outer ramus shorter than inner. Uropods reduced; uropod 1 biramous, stout, peduncle shorter than rami, with long inter-ramal process, both rami with several dorsal and distal robust setae; uropod 2 biramous, about half as long as uropod 1, inter-ramal process absent, tips of outer and inner rami with 2 and 4 robust setae, respectively; uropod 3 uniramous, about half as long as uropod 2, with several long setae terminally. Telson extremely short, entire, with pair of dorsal swellings.

Type species. Paragrandidierella minima Ariyama, 2002 (by monotypy).

Remarks. Although synonymized with Grandidierella by Ren (2006), Paragrandidierella is clearly different from Grandidierella in the following respects (features of Grandidierella in parentheses): (1) lower lip with minute projection on apical margin of inner lobe (no projection); (2) outer plate of maxilla 1 pointed apically, with 3 stout robust setae and 5–7 normal setae distally (not pointed, ca. 10 ordinary robust setae); (3) palp of maxilla 1 slender, with 3 short setae at tip (wide, with several robust setae at tip); (4) outer plate of maxilliped exceeding apex of palp article 2 (not reaching so far distally); (5) female gnathopod 1 simple (subchelate); (6) gnathopod 2 of both sexes simple (subchelate); (7) peduncle of uropod 1 stout, with long inter-ramal process (slender, with short inter-ramal process); and (8) telson extremely short with pair of dorsal swellings (relatively long, without swellings). These differences confirm the validness of Paragrandidierella . Ariyama (2002) described gnathopod 2 of both sexes of P. minima as “subchelate”; however, I correct this to “simple” based on the range of specimens studied herein.

The features of Paragrandidierella for separating from Grandidierella by Jung and Yoon (2013) almost share with those of Ariyama (2002) and the above features. However, two features are different: absence of accessory flagellum on antenna 1 and posterodistal protrusion on peduncle 5 of antenna 2. In the former, there is a possibility of overlooking because of its minuteness, and the latter is not a generic feature as stated below.

Included taxa. Paragrandidierella minima ; P. unidentata ; P. urauchiensis sp. nov.