Grandidierella sungeicina, Ali-Eimran & Lee & Azman, 2020

Ali-Eimran, Alip, Lee, Yen-ling & Azman, B. A. Rahim, 2020, Two new species of Grandidierella (Amphipoda, Corophiida, Aoridea) from Singapore, European Journal of Taxonomy 683, pp. 1-28 : 15-25

Grandidierella sungeicina sp. nov.

urn:lsid:zoobank.org:act:B5983965-F7CF-4F6A-94D9-BE0385CFF094

Figs 11–19

Etymology

This species is named after the type locality, Sungei Cina, Singapore.

Material examined

Holotype

SINGAPORE • ♂ (bl 7.35 mm); Sungei Cina river mouth; 01º26.969ʹ N, 103º43.696ʹ E; 26 Jan. 2011; CMBS staff and volunteers leg.; shallow water muddy bottom; ZRC 2018.0490 .

Paratypes

SINGAPORE • 1 ♀ (bl 7.12 mm); same collection data as for holotype; ZRC 2018.0491 • 3 ♂♂, 5 ♀♀, 4 juvs; same collection data as for holotype; ZRC 2018.0492 .

Type locality

Sungei Cina, Singapore.

Description (based on the holotype ♂, ZRC 2018.0490)

BODY. Subcylindrical.

HEAD. Longer than deep, longer than pereonites 1 and 2 combined, anteroventral margin moderately excavate. Eyes present and well developed, set just posterior to margin of lateral lobe. Epimeral plate 3 longer than 1 or 2.

ANTENNA 1 ( Fig. 12A 1). Longer than 2; weakly setiferous; peduncular articles 1–3 with ratio of 5:7:2; peduncular article 1 with robust setae on ventral margin; peduncular article 2 slender; peduncular article 3 shorter than 1 or 2; accessory flagellum present, minute, uniarticulate, apically rounded; flagellum consisting of 17 articles, each article distally fringed with fine setae.

ANTENNA 2 ( Fig. 12A 2). More robust than 1; peduncular articles 3–5 with ratio of 1:3:2; flagellum 4-articulate, distally fringed with slender setae, articles 3–4 possessing robust setae on ventral margin.

UPPER LIP ( Fig. 13 UL). Broader than long, apically truncate, distal margin prepubescent.

LOWER LIP ( Fig. 13 LL). Inner lobe smaller than outer lobe with short setae on distal margin; outer lobe longer than broad, distal margin rounded and with fine setae, distomedial margin with a pair of short blunt processes.

MANDIBLES ( Fig. 13 MD). Well developed, subtriangular; left incisor with 5 teeth, right with 4; lacinia mobilis with 4 teeth on both right and left sides; left mandible armed with 6 accessory blades, right mandible with 9 accessory blades; molar process well developed, rounded; palp well developed, triarticulate; article 1 with fine setae on proximolateral corner and long setae on distal margin, article 2 slender with long setae throughout entire length, article 3 spatulate with long setae throughout entire length, subapical setae plumose, apical setae serrate.

MAXILLA 1 ( Fig. 13 MX 1). Inner lobe vestigial, outer lobe distally truncate, medioproximal corner with a clump of slender setae, distal margin with 8 spinulate setae, laterodistal margin with fine setae; palp biarticulate, article 1 0.3 times as long as article 2, article 2 broadening distally, laterodistal margin with

a row of fine setae, distal margin with apical robust setae, distomedial margin with long sub-marginal setae.

MAXILLA 2 ( Fig. 13 MX 2). Both lobes apically rounded; inner lobe shorter than outer lobe, lateral margin convex, medial margin with row of long slender setae; outer lobe lateral margin with short setae, apical setae serrate, subapical setae slender.

MAXILLIPED ( Fig. 13 MXP). Inner lobe reaching distal end of article 1 of palp, distal end truncate with plumose setae along entire margin, medioproximal margin with long plumose setae, distolateral corner with fine setae; outer lobe almost reaching distal end of palp article 2, medial margin straight with long slender and robust setae, lateral margin convex with long fine setae on proximal half and short setae on distal half of margin; palp 4-articlulate, article 2 medial margin with long slender setae, article 3 spatulate, distal end with long slender and serrate setae, article 4 subtriangular, apically truncate ending in a stout spine.

GNATHOPOD 1 ( Fig. 12G 1). Larger than gnathopod 2, carpochelate; distal articles highly setiferous; coxa small, subquadrate; basis proximoposterior margin notched, posterior margin expanded and slightly convex, distoposterior margin with slender setae, anterior margin straight; ischium subquadrate, distoposterior margin with slender setae; merus subtriangular, distoposterior margin with row of slender setae; carpus enlarged, at least twice as long as propodus, dorsal margin convex, ventral margin straight with a row of short plumose setae and submarginal short setae, palm with processes forming a broad excavate sinus; propodus ventral margin produced, with long slender setae, dorsal margin with long plumose setae; dactylus falcate; subequal in length to propodus.

GNATHOPOD 2 ( Fig. 12G 2). Subchelate; distal articles highly setiferous; coxa subquadrate; basis slender, slightly expanding distally; ischium subquadrate; merus subquadrate, distal margin possessing long plumose setae; carpus slightly shorter than propodus; dorsal margin straight, ventral margin convex and lined with long plumose setae; propodus slender, dorsal margin possessing long plumose setae, inner face with transverse row of proximal long plumose setae, palmar margin denticulate, not defined by robust setae or spine, possessing submarginal robust setae; dactylus falcate, fitting palm.

PEREOPOD 3–4 ( Fig. 14P 3–P 4). Coxae subhastate; basis anterior margin with short robust setae; ischium subquadrate, about 3 times as short as merus; merus expanding distally; carpus subovate, shorter than propodus; propodus slender; dactylus falcate, subequal in length to carpus.

PEREOPOD 5 ( Fig. 14P 5). Short; coxa posteriorly produced; basis broad, anterior margin with short robust setae; ischium subquadrate; merus longer than carpus, distal corners with long robust setae; carpus posterior margin with 3 robust setae; propodus slender, posterior margin with a row of robust setae, anterodistal corner with long setae; dactylus falcate.

PEREOPOD 6 ( Fig. 14P 6). Shorter than 7; coxa anteriorly produced; basis anterior margin with row of short robust setae, posterior margin with long plumose setae on distal half; ischium with slender setae on anterior margin; merus slender; carpus shorter than propodus with robust setae on dorsal and ventral margins; propodus long, expanding distally, dorsal margin with 6 robust setae, ventral margin with 3 robust setae, ventrodistal corner with clump of long slender setae; dactylus about 0.3 times as short as propodus.

PEREOPOD 7 ( Fig. 14P 7). Coxa small; basis anterior and posterior margins setiferous with long plumose setae; ischium subquadrate; merus slender posterior margin with 5 robust setae; carpus slender with many robust setae along entire length; propodus slightly expanding distally with robust setae along anterior and posterior margin, posterodistal corner with clump of long slender setae; dactylus falcate.

UROPOD 1 ( Fig. 15U 1). Biramous, inner and outer rami subequal in length; peduncle longer than rami, lateral margin with 6 robust setae, inner margin with 4 robust setae, interramal spine present and shorter than peduncle; outer ramus lateral margin with 4 robust setae, medial margin with 2 robust setae, apice with 5 robust setae; inner ramus with 4 robust setae, apice with 4 robust setae.

UROPOD 2 ( Fig. 15U 2). Biramous; peduncle subequal in length to inner ramus, lateral margin with 2 robust setae, medial margin with 1 robust setae; outer ramus longer than inner ramus, lateral margin with 4 robust setae, medial margin with 2 robust setae, apice with 5 robust setae; inner ramus 1 marginal setae, apice with 5 robust setae.

UROPOD 3 ( Fig. 15U 3). Uniramous subquadrate, as broad as long, about 0.3 times as short as ramus; ramus 4 times as long as broad, lateral margin with 4 long robust setae, medial margin with 3 long robust setae, apice with 4 long robust setae.

TELSON ( Fig. 15T). Entire, broader than long, distal margin convex, superficial face with long robust setae near median margin progressing to shorter setae near distal corners.

Female (dimorphic characters; based on the paratype ♀, ZRC 2018.0491)

GNATHOPOD 1 ( Fig. 16G 1). Subchelate; coxa subtriangular; basis slightly expanded posteriorly; ischium subquadrate, ventrodistal corner with long slender setae; merus subquadrate ventrodistal corner with long slender setae; carpus almost twice as long as broad, ventrally convex possessing serrate and slender setae, dorsodistal corner with robust setae; propodus subequal in length to carpus, palm denticulate, margin defined by robust setae; dactylus falcate, doubly serrate, extending beyond palmar margin. Additional illustrations ( Figs 17–19) are also provided for future reference.

Remarks

Grandidierella sungeicina sp. nov. is rather similar to illustrations made by Asari & Myers (1982) and Ledoyer (1979) of G. gilesi . However, there is much morphological variation of the gnathopod 1 propodus. Both Asari & Myers (1982) and Ledoyer (1979) showed no processes on the ventrodistal corner of the gnathopod 1 propodus, Chilton (1921) showed an apically acute process mid-margin while Myers (1981) had a blunt process. Grandidierella sungeicina sp. nov. on the other hand has an apically acute process. The new species also differs from G. gilesi wherein the merus of gnathopod 2 is distally truncate, instead of rounded, the ventral margin of the carpus is more convex and the inner face of propodus possesses a transverse row of long plumose setae instead of being oblique. Pereopod 6–7 coxae on the ventral margin do not possess plumose setae.