Sergestes edwardsii Kröyer, 1855

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 : 55-61

Sergestes edwardsii Kröyer, 1855

( Figs. 6–10 )

Sergestes edwardsii Kröyer, 1855: 28 ; 1859: 246, 277, 284, 285, pl. 4: fig. 9a–k; Bate, 1888: 403, pl. 73: fig. 2; Borradaille, 1916: 81; Sund, 1920: 27; Hansen, 1896: 961; 1919; 26, pl. 2: fig. 3; Ilig, 1914: 363, fig. 25; 1927: 320, figs. 86, 89, 90, 99, 1922: 182, pl. II; figs. 19­i, 2a–f; Gurney and Lebour, 1940: 62, fig. 56; Dennell, 1940: 314, 320; Kensley, 1978: 8–13.

Sergestes occulataus Kröyer, 1855: 28 ; 1859: 243, 277, 284, 285, pl. 3: fig. 5a–f; Bate, 1888: 406, pl. 74: fig. I; Hansen, 1896: 963.

Sergestes brachyorrhos Kröyer, 1859: 272 , 281, 284, 285, pl. 5: fig. 13a,b.

Sergestes (Sergestes) edwardsii Yaldwyn, 1957: 8 ; Milne, 1968: 29–31;

Crosneir and Forest, 1973: 307, 320–322, figs. 108h, 109h,c, 110c,d.

Diagnosis

Body long ( Fig. 6A ), somewhat twice length of cephalothorax; segment sixth strongly compressed, about twice as long as high. Carapace with short, acute hepatic and supraorbital spines ( Fig. 6B ), strong hepatic and anterior ridges, and weak cervical and postcervical sulci. Rostrum slant ( Fig. 6C ), ascend, armed with single terminal tooth.

Telson distally rounded ( Figs. 6A, 6D ), exopod and uropod same as that of S.brevispinatus . Antennular peduncle inner flagellum in male clasping organ with deep proxmomesial notch and opposed curved whereas in female short,simple and straight spine same as that of S. brevispinatus . ( Fig. 6A ).

Third maxilliped of dactylii ( Figs. 7A, 7B, 7C ) distal spine on outer margins of subsegment 1, 2 and 4, and outer terminal spine on subsegment 6 tending to be relatively shorter in female. Dactylus and distal half of propodus of short spines structure, interspersed with single longer spines.

First pereiopod smaller than second pereiopods ( Figs. 8A, 8B, 8C, 8D, 8E ,). Second and third pereiopods elongate, slender, bearing stiff setae( Figs. 8D, 8E, 8F, 8G ); First pereiopod lacking chela; second and third pereiopods with minute chelae ( Figs. 8B, 8C, 8E, 8G ).

Petasma of male ( Figs. 9A, 9B ) with lobus inermis (LI) finger­like, strongly inflected at proximomesial margin, sometimes slightly expanded distally lobus terminalis (LT) lobes both fingerlike anterior lobe distally rounded, armed both anteriorly and posteriorly with large hooks posterior lobe slenderer, usually slightly shorter than anterior lobe, armed with single large terminal hook. Lobus connectens (LC) bilobed; inner lobe low, rounded, armed with row of large hooks extending longitudinally along posterior face, over distal margin, along anterior face to point below base of outer lobe; outer lobe bulbous, directed laterally, distally armed with several small hooks. Lobus armatus (LA) bilobed; inner lobe low, rounded, distally covered with numerous hooks; outer lobe slender, elongate, directed distolaterally, with large terminal hook and lateral row of four to six smaller hooks on proximoanterior margin. Processus ventralis (PV) extending to about level of inflection between lobus connectens (LC) and lobus armatus (LA). Pars media (PM) with three conspicuous projections on lateral margin.

Appendix masculina single ( Fig. 9C ) same as that of S.brevispinatus paddle­shaped lobe bearing spines on distal margin.

Thelycum of female ( Fig. 10A ) consisting of modified portions of third pereiopod and sixth thoracic sternite. Third pereiopod with broad, flat, proximal projection at proximomesial corner, low apical prominence at distomesial corner and elongate, greatly hollowed genital cavity containing occupying most or all of intervening mesial margin; narrow, membranous coxal lamella protruding mesially from coxosternal articulation. Sixth thoracic sternite anteriorly forming operculum projecting posteriorly over common slit­like aperture of sperm posterior half of sternite with low transverse ridge terminating beneath proximal projections on coxa in two low anteriorly directed sternal protuberances and with shallow groove extending along midline between transverse ridge and sperm receptacle aperture.

Distribution

Sergestes edwardsii is broadly distributed throughout the tropical Atlantic, Caribbean and Gulf of Mexico.

Remarks

Dactylus of third maxilliped with single mesial spines on outer margins of subsegments 1 and 2 in Judkins specimen but differs from present specimens with only mesial spine on subsegment 2.

No difference in petasma of Judkins and present specimens.

In Judkins thelycum of female third pereiopod coxa with broad, flat proximal projection at proximomesial corner, low apical prominence at distomesial corner, and elongate, greatly hollowed genital cavity containing ovipore occupying most or all of intervening mesial margin; narrow, membranous coxal lamella protruding mesially from coxosternal articulation. Sixth thoracic sternite anteriorly forming operculum projecting posteriorly over common slitlike aperture of sperm receptacles posterior half of sternite with low transverse ridge terminating beneath proximal projections on coxa in two low anteriorly directed sternal protuberances and with shallow groove extending along midline between transverse ridge and sperm receptacle aperture.

Map 1–2. Geographical distribution of Sergestes brevispinatus and Sergestes edwardsii (combined).

Figures

FIGURE 6. Sergestes edwardsii Kröyer, 1855: Adult male; A ­lateral;carapace; C­rostrum; Dtelson and left uropod, lateral.

FIGURE 7. Sergestes edwardsii Kröyer, 1855. Adult male: A—clasping organ of lower antennular flagellum (left); ventral; 3ap; I–VII, 1st to 7th segments; cp; B—left third maxilliped; C—left third maxilliped dactylus further enlarged; D—apex of the dactylus.

FIGURE 8. Sergestes brevispinatus Judkins, 1978. Adult male: A—left first pereiopod; B—carpopropodalarticulation, 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 9. Sergestes edwardsii Kröyer, 1855. Adult male: A—petasma (left), dorsal; Ip,; pb; pu; pe; pm; sh; pv,; la; lac; lc; lt; li; pa; B—petasma (right) dorsal view; Ip; pb; pu; pe; pm; sh; pv; la; lac; lc; lt; li; pa; C— left appendix masculina.

FIGURE 10. Sergestes edwardsii Kröyer, 1855 Adult female: A—female exterior sexual organ, ventral; thelycum and coxae of third pereiopods, postero­ventral view; op; ap; gc; pxp; mp; pp.