Quadrimaera okha Thacker, Myers & Trivedi, 2024, sp. nov.
Creators: name: Thacker, Dimple
name: Myers, Alan A.
name: Trivedi, Jigneshkumar N.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Maeridae
Quadrimaera
Quadrimaera okha

description: 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)
description: Published as part of Thacker, Dimple, Myers, Alan A. & Trivedi, Jigneshkumar N., 2024, On a small collection of Maeridae Krapp-Schickel, 2008 (Crustacea: Amphipoda) from Gujarat, India, pp. 563-583 in Zootaxa 5474 (5) on pages 578-581, DOI: 10.11646/zootaxa.5474.5.7, http://zenodo.org/record/12682122