Sergestes brevispinatus Judkins, 1978

Yousuf, Farzana & Kazmi, Si. B., 2005, First record of Sergestes belonging to edwardsii species group (Sergestidae, Crustacea) from the Indian Ocean, Zootaxa 1092 (1), pp. 47-63 : 49-54

Sergestes brevispinatus Judkins, 1978

( Figs.1–5 )

Sergestes brevispinatus Judkins, 1978: 13 .

Diagnosis

Body long, slender, fragile ( Fig. 1A ).

Carapace ( Fig. 1B ) with short acute hepatic and supraorbital spines, hepatic and anterior ridges. Rostrum short ( Fig. 1C ) hardly elevated, apically acute, anterior margin vertically armed with single terminal tooth. No supra­orbital ridge, Cervical groove welldeveloped with small hepatic spine at its base.

Strong suprabranchial ridge present. Eyes well developed, eyestalks lacking occular tubercle.

Telson distally rounded ( Figs.1A, 1D ).

Antennular peduncle ( Figs.1A , 2A ) about three­fourths as long as carapace, outer margin of segment 1 longer than that of segment 2. Armed with distolateral tooth on basal segment. Antennal flagellum more than twice length of body, divided into proximal and distal parts by short section of annuli forming double band. Inner flagellum in male clasping organ with deep proxmomesial notch whereas in female short, simple and straight spine.

Third maxilliped ( Figs. 2B, 2C ) dactylii with single mesial spine on outer margin of subsegments 1 and 2. Outer distal spine on subsegment 1 seldom reaching beyond subsegment 2; outer distal spine on subsegment 2 seldom reaching beyond subsegment 4; outer distal spine on subsegment 4 very short; outer terminal spine on subsegment 6 usually less than length of inner terminal spine. Distal spines on outer margin of subsegments 1, 2 and 4 and outer terminal spine on subsegment 6 tending to be relatively shorter, and inner margin spines more numerous in females.

All pereiopods slender ( Figs. 3A–3I ); first pereiopod small ( Figs. 3A, 3B, 3C ),

First pereiopod about two thirds as long as second pereiopod ( Figs. 3D, 3E ).

Third pereiopod longer than second pereiopod ( Figs. 3F, 3G ); first pereiopod armed with numerous barbed spines at carpopropodal articulation( Fig. 3B ). First.pereiopod and second pereiopod armed with curved tooth on lateral margin of ischium. Chelae with dactylus slightly longer than palm, both dactylus and palm bearing terminal tufts of long setae ( Figs. 3C, 3E, 3G ), fourth pereiopod and fifth pereiopod laterally flattened, bearing natatory setae on all but leading margin of distal two segments ( Figs. 3H, 3I ), fifth pereiopod shorter than of fourth ( Figs. 3H, 3I ).

Petasma of male ( Figs. 4A, 4B ) very similar to S. edwardsii but differing in lobus inermis (LI) proximally more rounded and seldom expanded distally; lobus terminalis (LT) posterior lobe usually slightly longer than anterior lobe; lobus connectens (LC) inner lobe armed with hooks posteriorly and distally, but not anteriorly; pars lobus armatus (LA) outer lobe armed with six to eleven hooks along proximoanterior margin; lobus inermis (LI) and lobus terminalis (LT) anterior lobe tending to be longer relative to carapace length.

Appendix masculina single ( Fig. 4C ) paddle­shaped lobe bearing spines on distal margin.

Thelycum of female ( Fig. 5A ) with third coxa and sixth thoracic sternite.

Sixth thoracic sternite anteriorly forming operculum (OP) projecting posteriorly over common slit­like aperture of sperm receptacles; posterior half of sternite with low transverse ridge terminating beneath proximal projections (PP) on coxa in two low, anteriorly directed sternal protuberances (PB) and with shallow groove extending along midline between transverse ridge and receptacle aperture. Genital cavity (GC) relatively narrow in ventral view, extending distally.

Distribution

Sergestes brevispinatus . appears to prefer oceanic waters close to continental margin of Central and South America, eastern tropical Pacific and now from Indian Ocean.

Remarks

According to Judkins (1978) the shortness of the outer distal and outer terminal spines on the maxilliped third dactylus and are relatively similar spines in present specimens. Whereas petasma of male of Judkins processus ventralis (PV), lobus armatus (LA) and lobus connectens (LC) are very prominent but in present specimen processus ventralis (PV) is totally absent. Lobus armatus (LA) thin and lobus connectens (LC) very reduced.

Figures

FIGURE 1. Sergestes brevispinatus Judkins, 1978. Adult male: lateral; B—carapace; C—rostrum, D— telson and left uropod, lateral.

FIGURE 2. Sergestes brevispinatu, Judkins, 1978. Adult male: A—clasping organ of lower antennular flgellum (left), ventral; 3 ap, I–VII, 1st to 7th segments; cp; B— left third maxilliped; C— left third maxilliped, dactylus.

FIGURE 3. Sergestes brevispinatus Judkins, 1978. Adult male: A—left first pereiopod; B—carpo­propodal articulation,further enlarged; C—chela of first pereiopod; D—left second pereiopod; E—chela of second pereiopod,further enlarged; F—left third pereiopod; G—chela of third pereiopod further enlarged; H—left fourth pereiopod; I—left fifth pereiopod.

FIGURE 4. Sergestes brevispinatus, Judkins, 1978. Adult male: A—petasma (left), dorsal; Ip, pb; pu; pe; pm; sh; pv; la; lac; lc; lt; li; pa; B—petasma (right), dorsal; Ip; pb; pu; pe; pm; sh, sheath; pv; la; lac; lc; lt; li; pa; C—left appendix masculina.

FIGURE 5. Sergestes brevispinatus Judkins, 1978. Adult female: A—exterior sexual organ, ventral; thelycum and coxae of third pereiopods, postero­ventral view; op; ap; gc; pxp; mp; pp.