Acanthochondria zebriae, Ho, Kim I.H. & Kumar, 2000

Acanthochondria zebriae sp. nov.

( figures 1-2 View FIG View FIG )

Material examined. Twenty-four adult and three juvenile ♀♀ (19 with attached ♂) on gill fi laments of Zebrias synaturoide s (Gilchrist): four adults and three juveniles collected on 11 March 1994 and 20 adults collected on 26 December 1994. Holotype ( USNM 285490 About USNM ) and eight paratypes ( USNM 285491 About USNM ) have been deposited in the US National Museum of Natural History, Smithsonian Institution, Washington, DC and the remaining paratypes and other specimens kept in the junior authors’ ( IHK) collection.

Female. Body ( figure 1A View FIG ) elongated and cylindrical, measuring 1.69-1.94 mm long. Head ( figure 1B View FIG ) longer than wide, 403✕ 273 μ m (not including inflated antennule), with small rounded knob at each anterolateral corner and ventrally protruded oral region ( figure 1C View FIG ). First pediger narrower than head. Second pediger with remaining prosomal somites fused into a long, cylindrical trunk bearing a pair of posterolateral processes ( figures 1D, E View FIG ). Genital double somite slightly longer than wide, 135✕123 μ m, and abdomen distinctly wider than long, 37✕ 65 μ m. Caudal ramus ( figure 1D View FIG ) a spiniform, pointed process bearing four setae. Egg sac about as long as trunk.

Antennule ( figure 1F View FIG ) fl eshy and inflated; armature being (from proximal to distal) 1-1-2-2-2-7. Antenna ( figure 1G View FIG ) two-segmented; terminal segment sharply curved and covered with minute tubercles on terminal area of basal half before bend. Labrum with smooth, straight posterior margin. Mandible ( figure 1H View FIG ) two-segmented; terminal blade with 31 to 33 teeth on convex (inner) side and 28 to 32 teeth on concave (outer) side. Paragnath ( figure 1I View FIG ) a small spinulose lobe. Maxillule ( figure 1J View FIG ) with two terminal elements. Maxilla ( figure 1K View FIG ) two-segmented; first segment robust and unarmed; second segment bearing one small, simple, basal seta, one large seta with hyaline tip and a row of 22 to 29 teeth on terminal process. Maxilliped ( figure 2A View FIG ) three-segmented; first segment largest but unarmed, second segment with long spines on greatly protruded inner distal corner, and terminal segment reduced to a small hook situated opposite to tuft of spinules on inner-distal corner of second segment. Both leg 1 ( figure 2B View FIG ) and leg 2 (figure C) nearly unilobate, with inflated, bluntly pointed exopod continuous with protopod and carrying a much reduced endopod tipped with a seta. Terminal region of exopod with six setae on leg 1 and four setae on leg 2.

Male. Body ( figure 2D View FIG ) 217 μ m long, with swollen cephalosome and cylindrical metasome and urosome. Genital somite ( figure 2E View FIG ) with usual ventrolateral ridges. Abdomen ( figure 2E View FIG ) indistinguishably fused with genital segment. Caudal ramus as in female but naked. Antennule reduced to a simple seta (see figure 2D View FIG ). Antenna ( figure 2F View FIG ) with small seta on basal segment and a conical process on basal part of terminal hook. Mandible ( figure 2G View FIG ) with fewer teeth on terminal blade, 17 on convex side and ten on concave side. Maxilla ( figure 2H View FIG ) with eight or nine teeth on inner side and single one on outside of terminal process. Maxilliped ( figure 2I View FIG ) essentially as in female, but terminal claw relatively larger. Leg 1 ( figures 2D, J View FIG ) reduced to a simple spiniform seta. Leg 2 absent.

Etymology. The speci fi c name zebriae refers to the host of the present species.

Remarks. According to Ho and Kim’s (1995) designation of the variable appendages useful in species identi fi cation in the genus Acanthochondria , the antennule of the new species belongs, undoubtedly, to Type G -I, but its legs do not fit well to any of the five types. Basically, the legs of A. zebriae are attributable to Type A, but no species of Acanthochondria with Type A leg has its endopods on both legs 1 and 2 reduced to a small knob as in the present species. Furthermore, no species of Acanthochondria has the male with leg 2 missing and leg 1 reduced to a spiniform seta. The subchelate female maxilliped is another unusual feature of the present species.