Neomegamphopus malabarensis, Myers, 2004

Myers, Alan, 2004, A new species of amphipod of the genus Neomegamphopus (Crustacea, Amphipoda, Neomegamphopidae) from Rodrigues, Indian Ocean, Journal of Natural History 38 (23), pp. 3137-3142 : 3138-3141

Neomegamphopus malabarensis sp. nov.

( figures 1 , 2 )

HOLOTYPE: AMP 67446, male. Trou Malabar, 11 m, 22 September 2001, GPS: 19‡40.382'’S, 63‡25.081'E, clean sand in gulley.

PARATYPES: AMP 67445, five males and eight females, same data as holotype .

Description. Male 2.0 mm, female 2.0 mm. Head lateral cephalic lobes moderately strongly produced, triangular; eye triangular. Antenna 1 and 2 subequal in length. Antenna 1 peduncular articles in the length ratios 1:1.7:1.6, flagellum subequal in length with peduncle; accessory flagellum vestigial. Antenna 2 subequal in length with antenna 1, peduncular article 5 a little longer than article 4. Mouthparts of typical neomegamphid form, mandibular palp article ratios 1:2.5:2, article 3 spatulate with long setae confined to distal margin and subdistal posterior margin. Male gnathopod 1 carpus enlarged, subrectangular, basis swollen, a little over 1.5 times as long as broad, carpus enlarged, subovoid, the posterodistal margin produced into a blunt, triangular spine; propodus about half the length and two-thirds the breadth of the carpus, palm evenly convex, dactylus overlapping palm. Female gnathopod 1 coxa not enlarged, subsquare, basis slender and elongate, more than four times as long as broad, carpus and propodus slender, carpus the longer, propodus palm oblique, dactylus greatly overlapping palm. Male gnathopod 2 coxa subtriangular, basis moderately expanded about three times as long as broad, carpus scarcely longer than propodus, propodus palm oblique, dactylus slightly overlapping palm. Female gnathopod 2 similar to female gnathopod 1, but carpus and propodus subequal in length, palm more oblique. Pereopods 3–4 similar, basis flask-shaped, dactylus short, a little over half length of propodus. Pereopod 5 basis expanded, subovoid, about 1.3 times as long as broad. Pereopods 6 and 7 similar, basis subquadrangular, almost twice as long as broad, pereopod 7 slightly the longer. Epimera rounded. Uropod 1 inner ramus a little shorter than peduncle, outer ramus distinctly shorter than inner. Uropod 2 inner ramus about 1.25 times length of peduncle, and longer than outer ramus. Uropod 3 inner ramus 1.5 times length of peduncle terminating in a pair of stout setae, outer ramus with a small second article bearing an unequal pair of long slender setae. Telson dorsoventrally thickened, each dorsolateral crest bearing a stout seta.

Female with seven eggs.

Remarks. This species is readily distinguished from all other known species of Neomegamphopus by the subovoid carpus of the male gnathopod 1.

Etymology. Named after the type locality.

Key to male Neomegamphopidae of the Indian Ocean

1 Gnathopod 1 carpus posterodistal margin lacking spines or process, accessory flagellum multiarticulate................... 2

– Gnathopod 1 carpus with one or more distinct posterodistal spines or a rounded process, accessory flagellum with one long and one vestigial article...... 3

2 Gnathopod 1 propodus subchelate, palm with two well-developed spines......................... Maragopsis bidentata

– Gnathopod 1 propodus almost simple, palm almost obsolete without spines....................... M. obliquimanus

3 Gnathopod 1 coxa length greater than 1.6× breadth; propodus length greater than 3× breadth...................... 4

– Gnathopod 1 coxa length less than 1.2× breadth; propodus length less than 3× breadth........................ 5

4 Gnathopod 1 carpus subrectangular, with acute posterodistal spine......................... Neomegamphopus kunduchii

– Gnathopod 1 carpus subovoid, with subacute posterodistal spine.......................... N. malabarensis sp. nov.

5 Gnathopod 1 carpus produced into a rounded lobe, propodus palm excavate and produced into a strong spine opposable to the dactylus... Konatopus storeyae

– Gnathopod 1 carpus produced into one or more distinct spines, propodus palmar margin not produced into a spine................ 6

6 Gnathopod 1 carpus posterodistal margin produced into two or three spines K. latipalma

– Gnathopod 1 carpus posterodistal margin produced into a single spine. K. tulearensis

Figures

FIG. 1. Neomegamphopus malabarensis sp. nov., male holotype AMP67446, female paratype AMP67445, Trou Malabar, Rodrigues.

FIG. 2. Neomegamphopus malabarensis sp. nov., male paratype (entire specimen) AMP67445, male holotype (urosome, appendages) AMP67446, Trou Malabar, Rodrigues.