Paragrandidierella unidentata ( Ren, 2006 )

Ariyama, Hiroyuki, 2013, Reinstatement of Paragrandidierella (Crustacea: Amphipoda: Aoridae) from Japan, with the Description of a New Species, Species Diversity 18, pp. 223-235 : 229-233

publication ID	https://doi.org/ 10.12782/sd.18.2.223
publication LSID	lsid:zoobank.org:pub:8C5EF755-9772-41E1-BDF5-4E13C36ACE87
persistent identifier	https://treatment.plazi.org/id/1C29879C-FF9D-D223-78C2-C64CFC3E7307
treatment provided by	Felipe
scientific name	Paragrandidierella unidentata ( Ren, 2006 )
status

Treatment

Paragrandidierella unidentata ( Ren, 2006) View in CoL ( Figs 5–8 View Fig View Fig View Fig View Fig )

[New Japanese name: Wakaura-himedorosokoebi]

Grandidierella unidentata Ren, 2006: 377 View in CoL , 536, fig. 161.

Material examined. Five males (OMNH-Ar-9549– 9553), 2.4, 2.4, 2.2, 2.1, 1.7 mm, and two females (OMNH- Ar-9554, 9555), 2.7, 2.3 mm, mouth of Waka River in Wakayama City , Wakayama Prefecture (34°11.0′N, 135°10.4′E), tidal flat, middle intertidal zone, 13 March 2005, coll GoogleMaps . H GoogleMaps . Ariyama.

Description of male [based on 2.1 mm individual (OMNH-Ar-9552)]. Body ( Fig. 5 View Fig ) rather stout. Eyes somewhat large (30% as long as head). Posteroventral corners of pereonites 5–7 slightly produced. Urosomite 1 with dorsolateral ridge.

Antenna 1 ( Fig. 6A, A View Fig 1 View Fig ) relatively short, about half as long as body; length ratio of peduncular articles 1–3 1.0: 0.8: 0.3, article 1 with dorsal robust seta, articles 1 and 2 each with ventral plumose setae; flagellum with 9 normal and 1 minute articles, articles 4 and 6–9 each with aesthetasc on dorsodistal corner. Antenna 2 ( Fig. 6B View Fig ) short, about 0.3 times as long as body; length ratio of peduncular articles 3–5 1.0: 1.5: 1.1, article 3 bearing robust seta on dorsal surface, ventrodistal corner of article 5 not inflated; flagellum short, but slightly longer than peduncular article 5, consisting of 3 normal and 1 minute articles, flagellar articles 2 and 3 each with 2 robust setae.

Upper lip ( Fig. 6C View Fig ) with ventral margin slightly concave, bearing many thin setae. Right mandible ( Fig. 6D, D View Fig 1 View Fig ) with length ratio of palp articles 1–3 1.0: 1.8: 1.9, articles 2 and 3 with 2 and 10 setae, respectively; incisor with 3 cusps, lacinia mobilis with 2 cusps. Left mandible ( Fig. 6E, E View Fig 1 View Fig ) with length ratio of palp articles 1–3 1.0: 1.7: 1.9, articles 2 and 3 with 1 and 10 setae, respectively; incisor with 3 cusps, lacinia mobilis with 2 cusps. Lower lip ( Fig. 6F View Fig ) covered with thin setae on apical parts of outer and inner lobes. Maxilla 1 ( Fig. 6G, G View Fig 1 View Fig , G 2 View Fig ) with outer plate bearing 3 robust and 5 normal setae. Maxilla 2 ( Fig. 6H View Fig ) with inner margin of inner plate bearing sparse setae. Maxilliped ( Fig. 6I, I View Fig 1 View Fig ) with distal and medial margins of inner plate bearing many plumose setae; outer plate broad, middle and proximal parts not inflated laterally, medial margin with 6 thick, robust setae, tip bearing long, plumose seta.

Gnathopod 1 ( Fig. 7A, A View Fig 1 View Fig ) a little enlarged; carpus wide, posterodistal corner with short tooth (ca. 15% as long as carpus proper); propodus straight, posterior margin not expanded, with 2 robust setae; dactylus elongate-triangular, distal part of posterior margin with denticle. Gnathopod 2 ( Fig. 7B, B View Fig 1 View Fig ) slender; posterodistal margin of merus setose; carpus relatively elongate, posterior margin with many thick and normal setae; dactylus with 2 denticles posterolaterally.

Pereopods 3 and 4 ( Fig. 7C, D View Fig ) with coxae roundishrectangular, bases slender, meri dilated distally, carpi about same length as meri, propodi narrow, and dactyli long and dirk-shaped. Pereopod 5 ( Fig. 7E View Fig ) with coxa short, posterior half narrower than anterior; basis rectangular, anterodistal corner with thick seta; merus relatively broad; carpus with 2 lateral and 1 posterodistal robust setae; propodus with 3 lateral and 1 posterodistal robust setae; dactylus short, with plumose seta. Pereopod 6 ( Fig. 7F View Fig ) about 1.4 times as long as pereopod 5; coxa with posterior half narrower than anterior; basis longish ovoidal, anterior margin with 2 short robust setae, distal half of posterior margin with many plumose setae but no robust setae; merus with short lateral robust seta, anterior margin bearing 3 thick setae; carpus with 4 lateral robust setae, anterodistal corner with robust seta and long, thick seta, posterodistal corner with long, thick seta; propodus with 5 thick and 1 robust setae on anterior margin, medial margin bearing thick seta; dactylus bearing plumose seta. Pereopod 7 ( Fig. 7G View Fig ) about 1.5 times as long as pereopod 6; coxa small, anterior part produced ventrally; basis ovoidal, anterior margin with 2 short robust setae, posterior margin with many plumose and 1 robust setae; merus with 3 lateral and 3 anterior robust setae, anterodistal and posterodistal corners bearing thick setae; carpus with 3 lateral and 1 anterodistal robust setae, posterodistal corner and mediodistal edge each bearing long, thick seta; propodus bearing 4 robust setae on anterior margin, anterodistal corner with 1 robust and 1 long, thick setae; dactylus with plumose seta.

Epimeral plates 1–3 ( Fig. 8A View Fig ) each bearing short seta on posteroventral corner; plates 2 and 3 with 3 and 2 long, plumose setae on ventral margin, respectively. Pleopods ( Fig. 8B–D View Fig ) with outer rami composed of 8 articles, inner rami composed of 6–7 articles. Uropod 1 ( Fig. 8E View Fig ) stout; dorsal surface of peduncle with 1 robust and 1 normal setae distally; outer ramus slightly longer than inner, outer and inner rami each with 1 dorsal and 4 terminal robust setae. Uropod 2 ( Fig. 8F View Fig ) with peduncle shorter than wide; rami a little shorter than peduncle, outer ramus shorter than inner. Uropod 3 ( Fig. 8G View Fig ) with peduncle a little longer than single ramus, ramus with 4 long setae terminally. Telson ( Fig. 8G View Fig ) with pair of 3 setae.

Description of female [based on 2.7 mm individual (OMNH-Ar-9554)]. Generally similar to male except for antennae, gnathopods, and oostegites. Antenna 1 ( Fig. 8H View Fig ) relatively short, about 0.45 times as long as body; length ratio of peduncular articles 1–3 1.0: 0.8: 0.3; flagellum with 8 normal and 1 minute articles, articles 5–8 each with aesthetasc. Antenna 2 ( Fig. 8I View Fig ) short, 0.35 times as long as body; length ratio of peduncular articles 3–5 1.0:1.5: 1.2; flagellum short, of almost same length as peduncular article 5, consisting of 3 normal and 1 minute articles, flagellar articles 2 and 3 each with 2 robust setae. Gnathopod 1 ( Fig. 8J, J View Fig 1 View Fig ) with coxa trapezoidal; basis broadened distally; merus triangular, posterior margin with a few setae; carpus relatively broad, posterior margin with a few thick and normal setae; propodus slender, distal half of posterior margin with 4 robust setae; dactylus with denticle on distal part of posterior margin. Gnathopod 2 ( Fig. 8K, K View Fig 1 View Fig ) subequal in size to gnathopod 1; similar to that of male, but dactylus with 3 denticles posterolaterally.

Variation in male gnathopod 1 (5 males examined). Small male [1.7 mm (OMNH-Ar-9553), Fig. 8L View Fig ]: carpus more slender and tooth of carpus smaller than those of OMNH-Ar-9552 (ca. 5% as long as carpus proper). Large male [2.4 mm (OMNH-Ar-9549), Fig. 8M View Fig ]: tooth of carpus longer than that of OMNH-Ar-9552 (ca. 15% as long as carpus proper), posterior margin of propodus with 3 robust setae.

Remarks. The morphological features of this species agree well with those of Grandidierella unidentata Ren, 2006 , especially in the shape of the gnathopods and pereopods, but several differences are present [features of Ren’s (2006) description in parentheses]: (1) antenna 1 peduncle not slender, relatively short (slender, long), (2) accessory flagellum of antenna 1 vestigial (absent), (3) antenna 2 flagellum with 3 normal and 1 minute articles (4 normal and 1 minute articles), (4) flagellar articles 3 and 4 of antenna 2 each with 2 robust setae (1 robust seta each), (5) palp of maxilla 1 with 3 terminal setae (2 setae), (6) coxa 1 not projecting anteriorly (projecting), and (7) ramus of uropod 3 with 4 terminal setae (2–3 setae). (1), (3), and (6) of these differences may be due to the different body lengths of the specimens: 1.7–2.4 mm in the present study and 2.8 mm in Ren (2006). Paragrandidierella unidentata can be distinguished from P. minima by the lack of any inflation of male antenna 2, and from P. urauchiensis by the smaller tooth of the carpus of male gnathopod 1.

Distribution. Japan: mouth of Waka River, Wakayama Prefecture (present study). China: Qinglan, Hainan Province ( Ren 2006). In Japan, this species occurs only in the mouth of the Waka River, where the short-necked clam Ruditapes philippinarum (Adams and Reeve, 1850) has been introduced. Because great quantities of this clam have been imported from China, North Korea, and South Korea to Japan ( Ministry of Finance Japan 2013), there is a possibility that Paragrandidierella unidentata is an introduced species like the alien gastropods introduced with various edible bivalves from East Asia ( Tamaki et al. 2002; Okoshi 2004).

Habitat. Sandy-mud tidal flat, middle to lower intertidal zone (present study); sand and mud flats with seagrass, littoral ( Ren 2006).