Amblyops surugensis, Murano, 2012

Murano, Masaaki, 2012, The Genus Amblyops (Crustacea: Mysida: Mysidae: Erythropinae) from East Asia and Australia, with Descriptions of Ten New Species, Species Diversity 17 (1), pp. 49-85 : 74-76

Amblyops surugensis sp. nov.

(Figs 17–19)

Type series. H olotype: gravid female (22.1 mm), NS- MT-Cr 21364, RV “Tansei Maru”, KT-75-15 Cruise, St . 011- II, Suruga Bay o Matsuzaki, Izu Peninsula, central Japan, 25 November 1975, 1770– 1780 m, 2-m beam trawl, coll . S . Ohta . Paratype: adult female (18.7 mm), NSMT-Cr 21365, same data as holotype .

Description.C arapace (Fig. 17A) with broadly rounded anterior margin without de nite rostral projection, leaving most of eyeplates exposed; anterolateral corner rounded; posterior margin emarginate, leaving small part of last thoracic somite exposed dorsally.

Eyes (Fig. 17A) plate-like without visual elements, separated from each other, rather small, extending beyond middle of rst segment of antennular peduncle; each eyeplate rectangular with rounded corners, wider than long, without distinct papilliform projection on anterior margin, with scattered minute spinules on distolateral part.

Antennular peduncle (Fig. 17A) short and robust; rst segment wider than long, distolateral corner prolonged anteriorly and tipped with several setae; second segment very short; third segment as long as wide, slightly longer than combined length of preceding 2 segments, armed with more than 10 setae along mesial margin and several setae on distomesial margin.

Antennal scale (Fig. 17A, B) long, rather wide, overreaching distal margin of third segment of antennular peduncle by 3/5 of its length, 3.2 times as long as maximum width at proximal 2/5; lateral margin naked, slightly convex in proximal half, terminating in rather small denticle extending to apex of blade and armed with 1 (paratype) or 2 (holotype) spinules near basal end of inner side. Antennal peduncle (Fig. 17B, C) as long as antennular peduncle, 4-segmented; second segment short, connected to ventral side of third segment. Antennal sympod (Fig. 17A, B) with stout denticle at anterolateral corner.

Mandibular palp, maxillule, and maxilla as illustrated (Fig. 17D–G). Labrum with anterior margin rounded.

First thoracopodal endopod (Fig. 18A) short and robust, terminating in strong claw longer than dactylus. Second thoracopodal endopod (Fig. 18B) relatively robust; merus slightly curved inwardly, 4 times as long as wide, almost same in length as carpopropodus and dactylus combined; carpopropodus widened in middle part, about 3 times as long as wide; terminal claw strong, longer than dactylus. fflird thoracopodal endopod (Fig. 18C, D) slender, with subchelate termination formed by terminal claw and stout spinous setae at distomesial corners of dactylus and distal subsegment of carpopropodus; ischium twice as long as wide; carpopropodus as long as merus, 3-subsegmented, proximal subsegment connected obliquely with middle one and slightly longer than succeeding 2 subsegments combined, distal subsegment shortest, twice as long as wide, longer than combined length of dactylus and terminal claw; dactylus small, as long as wide. Sixth thoracopodal endopod (Fig. 18E) similar to that of third thoracopod in general, provided with rudimentary oostegite armed with long hairs; ischium 2.5 times as long as wide; proximal subsegment of carpopropodus connected obliquely with middle one and much longer than succeeding 2 subsegments combined. Eighth thoracopodal endopod (Fig. 18F) much more slen- der than those of preceding limbs, with developed oostegite; ischium 3 times as long as wide; merus equal to combined length of proximal 2 subsegments of carpopropodus; proximal subsegment of carpopropodus 1.7 times as long as combined length of distal 2 subsegments. Exopods of thoracopods (Fig. 18B, C, E, F) with 9- or 10-segmented agellum and basal plate with pointed distolateral corner.

First abdominal somite 1.3 times longer than second. Second, third, and fourth abdominal somites subequal. Fi h abdominal somite 1.3 times longer than fourth, sixth 1.5 times longer than h.

All pleopods of female reduced to unsegmented single lobes.

Uropodal endopod (Fig. 19A, B) tapering distally, reaching tips of apical spines of telson, armed with 3 spines on inner margin in statocyst region. Uropodal exopod (Fig. 19A) elongated, overreaching apex of telson by 2/5 of its length.

Telson (Fig. 19A, C) elongated linguiform with narrowly rounded apex, 2.6 times as long as maximum width near base, 1.5 times as long as last abdominal somite, somewhat abruptly narrowing near base, then gradually narrowing towards posterior end; lateral margin armed on about posterior 3/4 with 39 spines, these almost equally sized except for several slightly longer spines posteriorly and several shorter ones anteriorly; pair of inconspicuous apical plumose setae emerging from dorsal surface rather far from posterior end of telson.

Etymology.ffl e speci c name, surugensis , is derived from Suruga Bay, where the present specimens were collected.

Remarks. A mblyops surugensis resembles A. amamiensis , A. kashimensis , and A. sagamiensis , in having eyeplates with no detectable papilliform projection and a telson lacking minute median spines on the apex but armed with about 40 spines on the posterior three-fourths of the lateral margin. Amblyops surugensis di ers from the latter three species in its more slender telson (2.6 times as long as wide in A. surugensis compared to 2.2 times in A. amamiensis , 2.3 times in A. kashimensis , and 2.4 times in A. sagamiensis ) and bigger body size (body length 19–22 mm in A. surugensis as against 13–15 mm in A. amamiensis , 15.6 mm in A. kashimensis , and 15–17 mm in A. sagamiensis ). Furthermore, it is distinguished from A. amamiensis and A. sagamiensis by the shape of the antennal scale (not narrowing distally as in the latter two species), and the thicker and stouter endopods of the third to eighth thoracopods. ffle new species is also distinguishable from A. kashimensis by the uropodal endopod, which has three spines on the inner margin in the statocyst region compared to one spine in A. kashimensis .