Bemlos quadrimanus (Sivaprakasam, 1970)

Wongkamhaeng, Koraon, Coleman, Charles Oliver & Pholpunthin, Pornsilp, 2013, Three new species from the Aoridae and Maeridae (Crustacea, Amphipoda) from Thai Waters, Zootaxa 3693 (4), pp. 503-533 : 504-512

Bemlos quadrimanus (Sivaprakasam, 1970)

( Figs 2–7 )

Lembos quadrimanus Sivaprakasam, 1970 : p. 81, fig. 1. Lembos waipio .—Ledoyer, 1972: 200, pls 21A, 22, 24. (not L. waipio Barnard, 1970: 85 , figs 44, 45).

Lembos quadrimanus mozambicus Myers, 1975: 359 , figs 33–39. Bemlos quadrimanus .—Myers, 1988: 188.

Material examined. 1 male 5.4 mm, PSUZC-CR-266. 1 female 5.0 mm, PSUZC-CR-267, ZMB 27983 5 male 5 gravid females, PSUZC-CR-278, 6 males and 6 females, 6°46'42"N 99°46'5"E, algae bed of Lidee Noi Island, Satun Province, Andaman Sea, Thailand, Rodcharoen, E., hand-collecting, 27 November 2011.

Type locality. Gulf of Mannar, Eastern India, Indian Ocean.

Description. Based on male, 5.4 mm.

Head. Lateral cephalic lobes truncate, anteroventral margin moderately recessed, anteroventral corner with small tooth, eyes present, oval shaped. Antenna 1 longer than antenna 2; flagellum with 19 articles; accessory flagellum with 6 articles, the terminal article rudimentary. Antenna 2 peduncle article 4 subequal to article 5; flagellum with 8 articles. Upper lip ventral margin slightly excavated. Lower lip outer lobe covered by long fine setae. Mandible incisors with 6 teeth, lacinia mobilis present with 3 teeth; setal row with 6 setae; mandibular palp articles 1–3 ratio 1:1.3:2, article 2 sparsely setose, article 3 slightly falcate, inner margin with 10 long plumose setae and 24 short bifid plumose setae. Maxilla 1 inner plate small with single long plumose setae; palp article 2 with 8 terminal robust setae.

Pereon. Pereonites 1–4 bearing 4 sternal processes, sternal spines not bifid. Gnathopod 1 larger than gnathopod 2, subchelate, coxa subrectangular, poorly setose; basis robust, 2 × as long as broad, anterior margin straight, mediofacial excavated; ischium rectangular; merus posterodistally produced into a tooth; carpus shorter than propodus, subtriangular, posterodistally produced; propodus robust, posterodistal margin sparsely setose, palm oblique with a deep excavation and subrectangular serrated distomedial edge; dactylus overlapping palm. Gnathopod 2 subchelate, coxa rounded; basis slender, much less than half as broad as long, with anterodistal tooth; ischium smooth; carpus longer than propodus; palm oblique with a defining robust seta; dactylus overlapping palm. Pereopod 3 and 4 similar, basis smooth; merus weakly setiferous; dactylus shorter than propodus. Pereopods 5–7 in the length ratio 1: 1.5:2, pereopods 6 and 7 basis with plumose setae on posterior margin.

Pleon. Epimera 2–3 with small posterodistal tooth and a setule on each posterodistal notch; epimeron 2 sparsely setose ventrally. Uropod 2 peduncle with ventrodistal process; rami 1.5 × peduncle. Uropod 3 peduncle with 3 robust setae; rami obtuse distally, subequal; peduncle shorter than rami, outer ramus without article 2. Telson longer than broad, with group of terminal setae, pointed apically.

Female -sexually dimorphic characters. Based on female 5.0 mm, PSUZC-CR-0267 (fig. 7). Pereon. Without sternal processes. Gnathopod 1 basis slender, 2.5 × as long as broad; merus short, posterodistal produced; carpus subtriangular, 1.3 × as long as propodus length; palm oblique with a defining robust seta; dactylus with accessory teeth, overlapping palm. Gnathopod 2 similar to that of male, basis slender; carpus subequal to propodus; palm oblique; dactylus overlapping palm.

Habitat. Among Padina and Halimeda algae, in coral rubble.

Remarks. Bemlos quadrimanus material studied herein resembles specimens from other populations from Indian, Africa and Australia. However, it differs from those specimens in its gnathopod 2 dactylus which is exceeding the palm and the mandibular palp ratios of articles 1–3 1:1.3:2 (vs. 1:2: 3 in the original description). It also shows the following differences from the original description: antenna 2 article 4 subequal to article 5 (vs.

shorter), female gnathopod 1 merus and carpus venterodistally produced (vs. unproduced) and uropod 1 peduncle shorter than rami (vs. subequal). Other morphological differences are concluded into Table 1 . On the basis of morphology we cannot decide if our material belongs to a separate species or if the small differences are in the range of a normal variability.

Distribution. East Africa (Myers 1975), Madagascar (Ledoyer 1972), India (Sivaprakasam 1970), Andaman Sea (current study), Western Australia (Myers 1988).

Figures

FIGURE 2. Bemlos quadrimanus (Sivaprakasam, 1970), male, 5.4 mm (PSUZC-CR- 0266), Lidee Noi Island, Andaman Sea. Scale bars: A 1 - 2 = 0.2 mm; MP, MX 1 = 0.1 mm.

FIGURE 3. Bemlos quadrimanus (Sivaprakasam, 1970), male (PSUZC-CR- 0266), 5.4 mm, Lidee Noi Island, Andaman Sea. All scale bars represent 0.2 mm.

FIGURE 4. Bemlos quadrimanus (Sivaprakasam, 1970), male (PSUZC-CR- 0266), 5.4 mm, Lidee Noi Island, Andaman Sea. Scale bars for UL and T represent 0.1 mm., remaining represent 0.2 mm

FIGURE 5. Bemlos quadrimanus (Sivaprakasam, 1970), male (PSUZC-CR- 0266), 5.4 mm, Lidee Noi Island, Andaman Sea. All scale bar represents 0.2 mm.

FIGURE 6. Bemlos quadrimanus (Sivaprakasam, 1970), male (PSUZC-CR- 0266), 5.4 mm, Lidee Noi Island, Andaman Sea. All scale bar represents 0.1 mm.

FIGURE 7. Bemlos quadrimanus (Sivaprakasam, 1970), female (PSUZC-CR- 0267), 5.0 mm, Lidee Noi Island, Andaman Sea. All scale bar represents 0.2 mm.

Tables

TABLE 1. Morphological differences between populations of Bemlos quadrimanus.

	antenna 2 article 4: article 5	mandibular palp ratio of article 1–3	female gnathopod gnathopod 2 epimeron 2 1 merus and dactylus carpus	uropod 1 peduncle: rami
Sivaprakasam 1970	<	1:2:3	not produced fitting palm without plumose setae	=
Ledoyer 1972	-	1:2:3	posterodistal fitting palm without plumose produced setae	=