Leucothoe jimi, Thacker, Dimple, Myers, Alan & Trivedi, Jigneshkumar, 2023

Thacker, Dimple, Myers, Alan & Trivedi, Jigneshkumar, 2023, A new species of sponge-inhabiting amphipod, Leucothoe jimi sp. n. (Amphilochidea: Leucothoidae) from Gujarat state, India, Journal of Natural History 57 (33 - 36), pp. 1516-1526 : 1518-1522

Leucothoe jimi sp. n.

( Figures 2–4 )

Type material

Holotype: 1 male, 6.5 mm ( LFSC.ZRC-196) Shivrajpur Beach INDIA (22°19 ʹ 53.4″N, 68° 56 ʹ 59.6″E), 22 March 2017, coll. J.N. Trivedi. Paratypes: 5 males, 5–6 mm ( LFSC.ZRC-196); 4 females, 4–6 mm ( LFSC.ZRC-198), same data as holotype .

Type locality

Shivrajpur Beach (22°19 ʹ 53.4″N, 68°56 ʹ 59.6″E), Dwarka , Gujarat, India .

Geographical distribution

So far known only from Shivrajpur Beach (22°19 ʹ 53.4″N, 68°56 ʹ 59.6″E), Dwarka , Gujarat, India .

Etymology

The new species is named in memory of the late Dr James K. Lowry, who spent nearly all of his working life studying amphipods while serving as a Senior Research Scientist at the Australian Museum Research Institute in Sydney, Australia, where he worked for more than 40 years.

Ecology

The type locality of L. jimi sp. n., Shivrajpur supports various marine habitats. The upper intertidal zone comprises sandy shore and dead coral rubble, while the middle and lower intertidal zones are made up of coral reef. The individuals of L. jimi sp. n. were found living in association with multiple species of sponges attached on the under surfaces of rock boulders and appear to be abundant in the lower intertidal zone where the undersides of rocks remain submerged during low tide.

Description. Based on the holotype, male, 6.5 mm.

Head. Lateral cephalic lobe rounded. Eyes large, subrounded. Antenna 1 peduncular article 1 longer than article 2; peduncular article 3 length 3.5 times length of article 2; accessory flagellum absent; flagellum 9 articulated ( Figure 3 ). Antenna 2 slightly shorter than antenna 1; peduncle 3 and 4 elongated; article 2 with single spine and article 3 with 3 medial spines ( Figure 3 ). Left mandible with 8 incisors; large lacinia mobilis; palp with 3 articles, article 2 longer than twice the length of article 3, article 2 and 3 sparsely setose, article 3 with 2 apical setae ( Figure 3 ). Right mandible with 9 spines; lacinia mobilis small ( Figure 3 ). Maxilla 1 inner plate with single apical seta; outer plate with several apical robust setae and 2 marginal robust setae; palp well-developed with 2 articles, article 2 with 4 apical robust setae ( Figure 3 ). Maxilla 2 inner plate with 2 apical and 6 lateral setae; outer plate more slender than inner plate with 3 apical robust setae and 8 lateral slender setae ( Figure 3 ). Labium outer lobes distally setose ( Figure 3 ). Labrum bilobed with apical row of setae ( Figure 3 ).

Maxilliped inner plates fused, apical lobes each with 3 small spines; outer plate with 4 long apical setae; palp 3 articulate ( Figure 3 ).

Pereion. Gnathopod 1 carpochelate; coxa anteroventral margin produced, ventral margin straight; basis long, medially inflated with 3 short setae on anterior margin, posterior margin bare; merus smaller than ischium; carpal spur subequal in length to propodus; propodus 3.6 times longer than broad, palm with 6 anterodistal robust setae; propodus inner surface serrated; dactylus almost half length of propodus ( Figure 4 ). Gnathopod 2 coxa subquadrate, dorsal, ventral and posterior margins almost straight, anterior margin slightly convex; basis linear, anterior margin with a few small to medium-sized simple setae, posterior margin bare; carpus densely setose, reaching slightly less than half the length of propodus, distal margin rounded and serrated; propodus elongate, robust, palm convex, with a few blunt projections of unequal size at distal end, propodus with one mediofacial setal row reaching almost half of the propodus; dactylus reaching around 0.7 times propodus length ( Figure 4 ). Pereopod 3 coxa subrectangular, anterior margin rounded; basis 3 times as long as broad; propodus with 5 small robust setae on posterior margin and 2 long setae near the base of the dactylus; dactylus almost half length of propodus ( Figure 4 ). Pereopod 4 coxa longer than broad, posterior margin slightly excavate; carpus with 2 robust setae on posterior margin and 2 near the distal end; propodus with 5 robust setae on the posterior margin and 2 at the base of the dactylus; dactylus more than half length of propodus ( Figure 4 ). Pereopod 5 basis expanded, almost 1.19 times longer than wide; dactylus almost twice the length of propodus ( Figure 4 ). Pereopod 6–7 carpus, propodus and dactylus broken off. Pereopod 6 basis expanded, 1.18 times longer than wide. Pereopod 6 basis expanded, 1.13 times longer than wide, almost oval in shape ( Figure 4 ).

Pleon. Epimeral plate 1 anteroventral margin straight, posterior margin excavate, anteroventral corner with a tuft of 4 small setae ( Figure 3 ). Epimeral plate 2 with 3 setae on ventral margin; posteroventral corner slightly produced ( Figure 3 ). Epimeral plate 3 anterior margin almost straight, anteroventral corner bare ( Figure 3 ). Uropod 1 longer than uropod 2; peduncle subequal to equal rami ( Figure 4 ). Uropod 2 peduncle 1.2 times longer than endopodite; exopodite 1.4 times longer than endopodite ( Figure 4 ). Uropod 3 missing. Telson 2.2 times longer than wide; telson tip serrated tip with 2 apical setae ( Figure 4 ).

Female (sexually dimorphic characters). Antenna 1 peduncular article 1 and 2 subequal in length. Antenna 2 peduncular article 2 shorter compare to male. Telson with pointed tip. Gnathopod 2 basis more slender and longer than in male. Gnathopod 2 propodus projections more blunt than in male ( Figure 5 ).

Remarks

Leucothoe jimi sp. n. is very similar to L. denticulata Costa, 1851 and L. spinicarpa Abildgaard, 1789 in having following characters: rounded lateral cephalic lobes; antenna 2 slightly shorter than antenna 1 and maxilla 1 inner plate with a single apical seta. But L. jimi sp. n. can be differentiated from these two closely related species by a few morphological characters. A comparison of the differentiating characters is given in Table 1.

Figures

Figure 2. Leucothoe jimi sp. n. (a) Male holotype: 6.5 mm (LFSC.ZRC-196); (b) female paratype: 5 mm (LFSC.ZRC-198); Shivrajpur Beach, Gujarat, India.

Figure 3. Leucothoe jimi sp. n., male holotype (LFSC.ZRC-196), 6.5 mm; Shivrajpur Beach, Gujarat, India. Scale bars: 0.5 mm.

Figure 4. Leucothoe jimi sp. n., male holotype (LFSC.ZRC-196), 6.5 mm; Shivrajpur Beach, Gujarat, India. Scale bars: 0.3 mm.

Figure 5. Leucothoe jimi sp. n., female paratype (LFSC.ZRC-198), 5 mm; Shivrajpur Beach, Gujarat, India. Scale bars: 0.3 mm.