Ensayara bifurcata, Horton, 2008

Horton, Tammy, 2008, Amphipoda from marine caves of Hong Kong Island, Journal of Natural History 42 (9 - 12), pp. 825-854 : 834-836

Family ENDEVOURIDAE Lowry & Stoddart, 1997

Ensayara bifurcata sp. nov.

( Figure 5 )

Holotype

Unique specimen, 2 mm, sex indeterminate, possibly juvenile, epifaunal site A10, entrance to Conic Island Cave , Hong Kong, NHM Reg. No. 2004.2946.

Description

Antenna 1, ordinary; peduncle of three articles, article 1 longer than article 2, article 2 longer than article 3; primary flagellum of eight articles, unreduced; accessory flagellum of three articles. Antenna 2 ordinary; flagellum of six articles, unreduced. Mouthparts: Maxillipedal palp of four articles, article 4 claviform. Pereonites 1–7 dorsally smooth. Gnathopod 1: simple; coxa 1 shorter than coxa 2 tapering distally with a simple seta on distal margin; anterior margin straight; basis long, slender, (length 4×breadth), anterior and posterior margins smooth with simple setae; ischium short, (length 1.5×breadth); merus, short, with patch of short setules on posterior margin; carpus short, posterior margin with one long and four short setae; propodus tapering distally, (length 3.8×breadth), one simple seta and one setule along posterior margin; dactyl conspicuous, hooked distally. Gnathopod 2: minutely chelate; coxa large, subequal to coxa 3, expanded distally, with 5 setules on distal margin; ischium long, (length 2.8×breadth); carpus short (length 2.3×breadth), longer than propodus; propodus short, subrectangular, (length 1.4×breadth), with patch of short setules on posterior margin, seven long simple setae anterodistally, decreasing in size; dactyl short. Pereopod 3: strongly prehensile, parachelate, coxa large, subequal to coxa 2 expanded slightly distally with 4 setules on distal margin; basis long (length 3.8×breadth); merus elongate, (length 2.5×breadth); carpus long, (length 3×breadth) and tapering distally; propodus expanded posteriorly to form convex palm with eight setules along the palmar margin and two robust setae distally; dactylus long, slender, slightly curved, meeting palm edge. Pereopod 4: simple, coxa deeper than wide, large posteroventral lobe with both anterior and posterior margins rounded, fringed with fine setae; dactylus long, slender, slightly curved. Pereopod 6: basis expanded posteriorly, posterior margin almost straight, with four setules; merus produced into a small lobe posteriorly; remaining articles missing. Pereopod 7: as pereopod 6 but with basis more expanded posteriorly, posterior margin concave distally with six setules. Uropod 1: biramous, inner and outer rami subequal with two short robust setae on the outer ramus and one short robust seta on the inner ramus; peduncle, longer than rami, with one shorter and one longer robust seta present on peduncle at base of rami. Uropod 2: biramous, with one robust seta on the inner margin of the outer ramus, peduncle subequal in length to rami. Uropod 3: biramous, well developed; outer ramus 1-articulate and bifurcate, inner fork shorter than outer fork, inner margin with fringe of microsetules; inner ramus reaching level of inner fork of outer ramus, with fringe of microsetules on outer margin. Telson: short, entire, with two anteriorly directed setae.

Remarks

The lysianassoid genus Ensayara Barnard, 1964 currently contains eight species. Ensayara can be distinguished from Endevoura Chilton, 1921 , the only other genus in the family Endevouridae ( Lowry and Stoddart 1997) by the dactyl of the maxilliped palp which is claviform rather than spatulate, in the unreduced flagellae of the antennae and in the smooth anterior margin of the gnathopod 1 basis.

A single specimen of Ensayara bifurcata sp. nov. was collected from Hong Kong. E. bifurcata differs from all other species in the genus most notably in the outer ramus of uropod 3 which is uniarticulate and bifurcate. In all other species, the outer ramus is biarticulate. This species, though undoubtedly new, is not described in full because the holotype is unique, fragile and possibly a juvenile. Nevertheless, enough characters are included here to distinguish it from other species until further material from the type locality is acquired.

Etymology

From the Latin bifurcus, meaning two-forked, alluding to the bifurcate outer ramus of uropod 3.

Figures

Figure 5. Ensayara bifurcata sp. nov.