Ceradocus (Denticeradocus) alama Myers & Nithyanandan, 2016

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 : 564-569

Ceradocus (Denticeradocus) alama Myers & Nithyanandan, 2016

( Figs. 1A , 2–4 )

Ceradocus (Denticeradocus) alama Myers & Nithyanandan, 2016 , 421, figs. 16–18.

Material Examined. 4 males, 8–10 mm; 2 females, 6 mm & 7 mm, ( LFSC.ZRC-214) Shivrajpur (22.3312 N 68.9496 E), 27 February, 2022, coll. D. R. Thacker .

Description. Based on male, 10 mm.

Head. Eyes large, ovate. Antenna 1 longer than antenna 2; flagellum longer than peduncle; peduncular article 1 0.92 times as long as article 2, article 3 one fifth of the length of article 2; accessory flagellum 7 articulate (fig. 2, A1). Antenna 2 half as long as antenna 1, peduncular article 4 1.23 times as long as article 5; flagellum 16 articulate (fig. 2, A2). Mandible accessory setal row well developed with 9 setae; palp 3 articulate, article 1 with acute distal tooth, article 3 0.43 times longer than article 2 (fig. 2, Md). Labium distal margins of outer and inner lobes setose (fig. 2, L). Maxilla 1 inner plate triangular with inner margin setose; outer plate with 8 apical robust setae; palp article 2 apically setose (fig. 2, Mx1). Maxilla 2 inner plate broader than outer plate; outer plate apically setose, inner plate with dense setae on apical and inner margin, dorsomedial surface with an oblique row of setae (fig. 2, Mx2). Maxilliped inner plate apically truncate with 11 apical and 4 marginal plumose setae; outer plate with 7 long to medium robust setae on distal margin, 8 small robust setae on inner margin; palp 4 articulate, article 2 and 3 densely setose, article 4 with a long apical robust seta (fig. 2, Mxp).

Pereon. Gnathopod 1 coxa anteroventral corner acute with few small setae, few simple setae on ventral margin; basis subequal to carpus, anterior margin bare, posterior margin sparsely setose, posterodistal corner with a tuft of simple setae, ischium smaller than merus, with a tuft of simple setae on posterior margin; merus subrectangular, anterodistal corner acutely produced, posterior margin setose; carpus anterior margin 2.41 times as long as merus, posterior margin densely setose, anterior margin with 3 stout setae and 1 thin simple setae, anterodistal corner with a tuft of simple setae; propodus 0.93 times as long as carpus, ovoidal, anterior margin with 5 small simple setae placed at somewhat equal distance, posterior margin densely setose, palm convex; dactylus subequal to palm (fig. 3, G1). Gnathopod 2 asymmetrical. Left Gnathopod 2 larger than right gnathopod 2, coxa subquadrate with produced posterodistal corner, basis 0.6 times as long as propodus, anterior margin bare, posterior margin with few setae, anterodistal corner acutely produced; ischium smaller than merus; merus subrectangular with anterodistal corner acutely produced, carpus triangular, posterodistally setose; propodus large, subovoidal, palm transverse with 3 small to large shelves, one small subquadrate shelf near the hinge of dactylus followed by a V-shaped excavation, a large subquadrate shelf, a large U-shaped excavation and a medium sized triangular shelf, posterodistal corner of the palm concave; dactylus subequal to palm (fig. 3, MG2).

Pereopod 3 longer than pereopod 4; coxa subquadrate, basis slender, both margins with long simple setae proximally while short robust setae medially and distally; merus 0.62 times as long as basis; carpus and propodus subequal; dactylus 0.42 times as long as propodus (fig. 4, P3). Pereopod 4 coxa broader than long, basis anteriorly slender, medially broader, merus 1.17 times longer than carpus; propodus 1.1 times longer than carpus; dactylus 0.4 times longer than propodus (fig. 4, P4). Pereopod 5 basis subrectangular, anterior margin lightly undulated, posterior strongly undulated; merus 0.8 times as long as carpus; dactylus 0.33 times longer than propodus (fig. 4, P5). Pereopod 6 longer than pereopod 7; basis subrectangular with anterior margin lightly undulated and posterior margin strongly undulated; merus 0.79 times longer than carpus; carpus subequal to propodus; dactylus 0.3 times as long as propodus (fig. 4, P6). Pereopod 7 basis similar as pereopod 6 but less undulated on both margins; merus 0.65 times as long as carpus; carpus subequal to propodus; dactylus 0.36 times as long as propodus (fig. 4, P7).

Pleon. Epimera 1–3 with dorsal, posteroventral and ventral teeth. Epimera 1–3 with 3, 4 and 5 spines respectively on ventral margin (fig. 2, Ep1–3). Urosomite 1–2 with dorsal and posteroventral spines. Uropod 1 peduncle 1.17 times as long as outer ramus, with well-developed basofacial seta and long spur at distal margin; outer ramus slightly longer than inner ramus (fig. 4, U1). Uropod 2 peduncle 0.74 times as long as outer ramus; inner ramus slightly shorter than outer ramus (fig. 4, U2). Uropod 3 peduncle 0.64 times as long as outer ramus; outer ramus slightly longer than inner ramus (fig. 4, U3). Telson deeply cleft, 1.21 times longer than wide, both halves pointed distally, each half with 5 setae on inner margin and 1 long and 1 short robust distal seta, distal long seta reaching between 0.5 to 0.6 times of the telsonic lobes (fig. 4, T).

Female (sexually dimorphic characters). Gnathopod 2 both similar in shape as male minor gnathopod 2, but one larger and more setose than another (fig. 3, FG2).

Geographical distribution. The species was so far reported only from its type locality, Kuwait ( Myers & Nithyanandan, 2016) , and here we have reported this species for the first time from India.

Remarks. The specimen examined here agrees with the description and illustrations of C. (D.) alama given by Myers & Nithyanandan (2016). However, the specimen examined here shows some variations, such as: gnathopod 1 propodus convex (fig. 3, G1) (vs. concave in C. (D.) alama cf. Myers & Nithyanandan 2016: fig. 15 MG1), cone gland reaching nearly half of the peduncular article 3 (fig. 2, A2) (vs. reaching more than half of the peduncular article 3 in C. (D.) alama cf. Myers & Nithyanandan 2016: fig. 16, Hd), pereopod 5 posterodistal corner is rounded (fig. 4, P5) (vs. posterodistal corner with a very strong, acute spine in C. (D.) alama cf. Myers & Nithyanandan 2016: fig.18, P5) and Uropod 3 rami are having robust setae on both margins (fig. 5, U3) (vs. robust setae on only one margin in C. (D.) alama cf. Myers & Nithyanandan 2016: fig. 17, U3). The specimen examined here (10 mm) is larger than the specimen of Myers & Nithyanandan (2016) (6.5 mm); thus, these variations could be because of the size difference.

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 2. Ceradocus (Denticeradocus) alama Myers & Nithyanandan, 2016, male (LFSC.ZRC-214): 10 mm, Shivrajpur, (22.3312 N 68.9496 E), Gujarat, India.

FIGURE 3. Ceradocus (Denticeradocus) alama Myers & Nithyanandan, 2016, male (LFSC.ZRC-214): 10 mm; female (LFSC. ZRC-214): 7 mm: Shivrajpur, (22.3312 N 68.9496 E), Gujarat, India.

FIGURE 4. Ceradocus (Denticeradocus) alama Myers & Nithyanandan, 2016, male (LFSC.ZRC-214): 10 mm, Shivrajpur, (22.3312 N 68.9496 E), Gujarat, India.