Quadrimaera okha, Thacker & Myers & Trivedi, 2024

Thacker, Dimple, Myers, Alan A. & Trivedi, Jigneshkumar N., 2024, On a small collection of Maeridae Krapp-Schickel, 2008 (Crustacea: Amphipoda) from Gujarat, India, Zootaxa 5474 (5), pp. 563-583 : 578-581

Quadrimaera okha sp. nov.

( Figs 1D , 12–14 )

Type material. Holotype female, 4.5 mm, ( LFSC.ZRC-212) Shivrajpur (22.3312 N 68.9496 E), 27 February, 2022, coll. D. R. Thacker . Paratype, 1 female, 4 mm, ( LFSC.ZRC-213) same data as holotype .

Etymology. The specific epithet “okha ” is derived from the “Okha Mandal”, a region where the type locality of the new species is located. The name is used as a noun in apposition.

Description. Based on holotype, female, 4.5 mm.

Head. Eyes large, ovate. Antenna 1 longer than antenna 2; peduncular article 1 0.88 times as long as article 2, article 3 0.24 times as long as of article 2; accessory flagellum 7-articulate (fig. 12, A1). Antenna 2 0.56 times as long as antenna 1, peduncular article 4 1.25 times as long as article 5; flagellum 6-articulate (fig. 12, A2). Maxilla 1 inner plate bullet shaped with 1 small, 1 medium and 2 long distal setae; outer plate with 8 apical robust setae; palp article 2 distally setose (fig. 12, Mx1). Maxilla 2 outer plate broader than inner plate (fig. 12, Mx2). Maxilliped inner plate apically truncate with few apical and 4 marginal plumose setae; outer plate with several long to small robust setae on distal margin and inner margin; palp 4 articulate (fig. 12, Mxp).

Pereon. Gnathopod 1 coxa anteroventral corner rounded with a row of simple setae on ventral margin; basis 1.18 times as long as carpus, anterior margin with two small setae; ischium posterodistal corner with a tuft of simple setae; merus subrectangular; carpus anterodistal corner with a single seta, posterior margin densely setose with posterodistal corner with a tuft of setae; propodus 0.83 times as long as carpus, suboval, anterior margin sparsely setose, posterior margin with 3 and posterodistal corner with 1 tuft of long setae; palm rounded with few small setae; dactylus longer than palm (fig. 13, G1). Gnathopod 2 coxa subrectangular, longer than broad; basis 0.57 times as long as propodus, anterior margin few small setae, posterior margin with one long seta; ischium subquadrate; carpus compressed; propodus enlarged, subovoidal, palm oblique with 2 rounded shelves and a U-shaped excavation between the shelves, posterodistal corner defined by a small process; dactylus a little shorter than palm inner margin with few small setae and an excavation (fig. 13, G2).

Pereopod 3 longer than pereopod 4; coxa subquadrate, basis anterior margin with a row of small setae, posterior margin sparsely setose; merus subequal to carpus, sparsely setose on both margins; carpus anterior margin with a single small seta, posterior margin lined with robust seta; propodus subequal to carpus, anterior margin with a single seta, posterior margin with five pairs of robust setae, dactylus bifid, 0.39 times as long as propodus (fig. 13, P3). Pereopod 4 almost similar to pereopod 3 except propodus 1.14 times as long as carpus (fig. 13, P4).

Pereopod 5 basis subrectangular with posterodistal corner produced; merus 1.31 times as long as carpus with 3 robust setae on posterior margin and 2 tufts of setae on the anterior margin; carpus 0.66 times as long as propodus, 2 robust setae on anterior margin, posterior margin bare; propodus anterior margin with a row of robust setae, posterior margin bare; dactylus bifid, 0.40 times as long as propodus (fig. 13, P5). Pereopod 6 basis subrectangular; merus 1.23 times longer than carpus, both margins setose; carpus 0.63 times as long as propodus, anterior margin with a tuft of long setae, posterior margin bare; propodus anterior margin with 3 tufts of long setae, posterior margin bare; dactylus bifid, 0.36 times as long as propodus (fig. 13, P6). Pereopod 7 basis suboval; merus 1.64, both margins setose; carpus 0.61 times as long as propodus; propodus anterior margin with 3 tufts of long setae; dactylus 0.37 times as long as propodus (fig. 13, P7).

Pleon. Epimera 1–3 posteroventral corner rounded. Epimeron 1 ventral margin bare. Epimera 2–3 ventral margin with 3 and 4 setae respectively. Uropod 1 peduncle 1.17 times as long as outer ramus, with well-developed basofacial seta and long spur at distal margin; outer ramus 1.14 times longer than inner ramus; inner ramus without marginal setae (fig. 14, U1). Uropod 2 peduncle 0.84 times as long as outer ramus; inner ramus subequal to outer ramus (fig. 14, U2). Uropod 3 peduncle 0.61 times as long as outer ramus; inner ramus 0.79 times as long as outer ramus (fig. 13, U3). Telson deeply cleft, as long as broad with 6 setae on distal margin of each lobe (fig. 14, T).

Geographical distribution. The species is so far known only from its type locality, Shivrajpur Gujarat, India .

Remarks. Quadrimaera okha sp. nov is very close to two congeners: Q. brownorum Hughes, 2015 and Q. caliban ( Ruffo, Krapp & Gable, 2000) in having an excavation on female G2 dactylus and telson lobes having more than 3 robust setae on the distal margin. But Q. okha sp. nov can be differentiated from these two close congeners ( Table 2 )

Figures

FIGURE 1. (A) Ceradocus (Denticeradocus) alama Myers & Nithyanandan, 2016 male, (LFSC.ZRC-214): 10 mm, Shivrajpur; (B) Ceradomaera plumosa Ledoyer, 1973, male (LFSC.ZRC-215): 10 mm, Zanzmer; (C) Maera gujaratensis sp. nov., male paratype, (LFSC.ZRC-210): 7 mm, Gopnath; (D) Quadrimaera okha sp. nov., male paratype, (LFSC.ZRC-213): 4.5 mm, Shivrajpur, Gujarat, India.

FIGURE 12. Quadrimaera okha sp. nov., female holotype (LFSC.ZRC-212): 4.5 mm, Shivrajpur, (22.3312 N 68.9496 E), Gujarat, India.

FIGURE 13. Quadrimaera okha sp. nov., female holotype (LFSC.ZRC-212): 4.5 mm, Shivrajpur, (22.3312 N 68.9496 E), Gujarat, India.

FIGURE 14. Quadrimaera okha sp. nov., female holotype (LFSC.ZRC-212): 4.5 mm, Shivrajpur, (22.3312 N 68.9496 E), Gujarat, India.