Spongicola de Haan, 1844

Saito, Tomomi & Komai, Tomoyuki, 2008, A review of species of the genera Spongicola de Haan, 1844 and Paraspongicola de Saint Laurent & Cleva, 1981 (Crustacea, Decapoda, Stenopodidea, Spongicolidae), Zoosystema 30 (1), pp. 87-147 : 91-94

Genus Spongicola de Haan, 1844

Spongicola de Haan, 1844 : pl. 46, fig. 9. — Bate 1888: 213. — Alcock 1901: 148. — A. Milne Edwards & Bouvier 1909: 264. — Holthuis 1946: 60; 1955: 147; 1993: 310. — Schram 1986: 284.

TYPE SPECIES. — Spongicola venusta [recte venustus ] de Haan, 1844, by monotypy.

GENDER. — Masculine.

SPECIES INCLUDED. — The following seven species are recognized in the genus: Spongicola andamanicus Alcock, 1901 ; S. depressus n. sp.; S. goyi n. sp.; S. levigatus Hayashi & Ogawa, 1987 ; S. parvispinus Zarenkov, 1990 ; S. robustus n. sp. and S. venustus de Haan, 1844 .

DISTRIBUTION. — All but one species of Spongicola are distributed in the Indo-West Pacific, at depths of 60-1060 m. Only S. parvispinus is known from the southeastern Pacific, at depths of 470- 485 m.

DIAGNOSIS. — Rostrum short, usually dentate dorsally. Carapace usually with postrostral submedian spine on either side of midline; antennal spine small; lateral surface usually with oblique row or cluster of spines (anterolateral spines) anteroventrally; cervical groove present or absent. Sixth pleonal somite unarmed or armed with lateral spine(s). Telson broadly triangular or lance shaped, with spinose dorsolateral carinae. Cornea well developed, globular, faceted, usually darkly pigmented; eyestalk armed with small spines. Second maxilliped with well developed exopod. Ischium of third maxilliped unarmed or armed with dorsolateral row of spines and ventral row of spines; exopod rudimentary or absent. First pereopod with well developed or rudimentary grooming apparatus. Second pereopod with all segments unarmed. Third pereopod largest; palm frequently with serrations on dorsal and ventral margins, sometimes with sharp dorsal carina. Dactyli of fourth and fifth pereopods usually biunguiculate; carpi and propodi sometimes subdivided. Lateral margins of uropodal exopod and endopod serrate; endopod often with 1 subproximal spine on middorsal carina.

GENERAL DESCRIPTION

Body stout; integument soft, surface naked. Rostrum short, directed forward, falling short of tip of antennal scale, narrow triangular in dorsal view; dorsal and ventral margins usually armed with small teeth; ventrolateral ridge distinct, confluent with orbital margin, occasionally with 1 or 2 tiny teeth. Carapace usually with postrostral submedian spine on either side of midline; antennal spine small, usually acuminate; hepatic spine(s) present or absent; orbital margin concave; pterygostomial angle produced anteriorly; anterolateral spines usually present, forming oblique row or cluster; cervical groove present or absent.

Thoracic sternum broadened posteriorly, with bi-lobed prominences on sixth to eighth somites; ventral surfaces of prominences concave.

Pleon smooth, somewhat depressed dorsoventrally, rounded dorsally. First somite short, divided in two sections, anterior section deeply depressed, overlapped by posterior part of carapace, overhung by prominent transverse carina; ventral margin of anterior section usually produced in blunt or acute projection (generally more acute in males than in females).Second somite sometimes with prominent transverse carina extending to pleuron. Third somite longest. Pleura of second to fifth somites rounded or bluntly pointed in females, acutely or subacutely pointed ventrally in males; pleural margins smooth in females, armed with tiny teeth or denticles in males. Sixth somite widened posteriorly, sometimes with small lateral spine(s) on dorsal surface and with tiny median spine on posterior margin. Telson broadly triangular or lance shaped; dorsal surface usually with pair of spines near base (= proximal spines), dorsolateral carinae each bearing row of spines; lateral margins each with shallow subproximal concavity, and armed with 1 submarginal spine near base and row of spines thereafter; posterior half of lateral margin fringed with plumose setae; posterolateral angle usually with 1 spine (posterolateral spine); posterior margin rounded, usually with 1 median spine (posteromedian spine).

Cornea well developed, globular, usually darkly pigmented, distinctly faceted; eyestalk armed with small spines on dorsal and mesial faces. Antennular peduncle overreaching rostrum but not reaching distal margin of antennal scale; first segment longest, 2-3 times length of second segment, stylocerite short; second segment longer than third; third segment nearly as long as wide, unarmed. Antennal basicerite stout, with small spine at distolateral angle and additional smaller spines on ventrolateral margin; dorsomesial surface with 1 small laminate process; antennal scale subsemicircular, lateral margin slightly concave, serrate, mesial margin fringed with plumose setae; dorsal surface with longitudinal carinae; carpocerite short, not reaching midlength of antennal scale.

Mandible ( Fig. 2A, B ) with palp consisting of 3 articles, distal article tapering distally, outer margin convex; molar and incisor processes clearly separated; mesial margin of incisor process bidentate, bordered by thin corneous edge. Maxillule ( Fig. 2C ) with simple, slender endopod tapering distally; coxal endite suboval, with submarginal row of stiff setae on outer surface; basial endite moderately broad, truncate distally, with several slender spines. Maxilla ( Fig. 2D ) with curved, slender endopod; coxal and basial endites both deeply bilobed, all lobes subequal in length; scaphognathite well developed, posterior lobe slightly elongate, subtruncate terminal margin with very long setae exceeding length of scaphognathite. First maxilliped ( Fig. 2E ) with broad endopod consisting of 2 or 3 articles; coxal endite bilobed; basial endite large, subtriangular, with concave mesial margin; exopod well developed, flagellar; epipod large, distinctly bilobed. Second maxilliped ( Fig. 2F ) with endopod composed of 7 segments; coxa with small rounded tubercles laterally; basis and ischium incompletely fused, trace of articulation still discernible ( Fig. 2G ); ischium very short; merus elongate, longer than distal three segments combined; carpus cup-shaped; propodus slightly broadened distally; dactylus large, subequal in length to propodus, with complicated pattern of setation; epipod slender, with well developed, distinctly lamellate podobranch; exopod well developed, flagellar. Third maxilliped with endopod composed of 7 segments; basis very short ( Fig. 2H ); ischium compressed, usually with dorsolateral and ventral rows of spines; merus somewhat twisted, sometimes with row of lateral spines; ventrodistal angle of carpus not produced; propodus as long as carpus, with well developed grooming apparatus; dactylus tapering distally; epipod slender; exopod rudimentary ( Fig. 2H ).

First pereopod unarmed on each segment; grooming apparatus well developed or rudimentary; palm cylindrical; carpus longest.Second pereopod generally similar to first pereopod, but distinctly longer, lacking grooming apparatus.Third pereopod largest; fingers each terminating in curved claw; dactylus often serrated on dorsal margin, cutting edge consisting of chitinous ridge; palm subcylindrical; dorsal margin serrated, sometimes carinated; ventral margin also with serration extending onto fixed finger; carpus broadened distally, sometimes armed with lateral spines; merus sometimes with dorsal row of teeth, distalmost strong, lateral margin usually armed with 1prominent distolateral spine; ischium usually armed with strong dorsodistal spine, and row of small teeth or denticles on dorsal and ventral margins.

Fourth pereopod moderately long and slender; dactylus compressed laterally, biunguiculate (ventral unguis shorter than dorsal unguis and clearly demarcated from corpus), sometimes triunguiculate in large specimens; propodus and carpus combined longer than merus and ischium combined; propodus sometimes subdivided, armed with single row of movable spines on ventral margin; carpus longest, sometimes subdivided, often with 1 small spine at ventrodistal angle; ischium and merus obliquely articulated; ischium unarmed. Fifth pereopod similar to fourth.

Pleopods without appendices internae; first pleopod lacking endopod; second to fifth pleopods biramous. Uropod with protopod stout; both rami elongate oval in shape; exopod serrated on lateral margin, with smooth carinae on dorsal surface; endopod serrated on lateral margin often with 1 subproximal spine on middorsal carina.

Gills trichobranchiate, 19 pairs; branchial formula summarized in Table 1.

Eggs numerous and small, diameter 0.4-1.1 mm ( Table 5).

SEXUAL DIMORPHISM

Species of Spongicola show noticeable sexual dimorphism in general body shape (more stout and more strongly depressed dorsoventrally in females than in males), strength of armature on the carapace, pleonal pleura and appendages (spines or teeth are larger in males than in females), lengths of the pereopods (longer in males than in females), shape and structure of the pleopods (much more compressed laterally and broader in females than in males), and width of the thoracic sternum (wider in matured females than in males). Spawning females show terminal conditions of the above characters ( Saito 2002).

REMARKS

Two species that have been assigned to Spongicola , S. japonicus Kubo,1942 and S.cubanicus Ortiz,Gómez & Lalana, 1994 , are not treated in this study, because the lack of an exopod on the third maxilliped set them apart from Spongicola . Furthermore, S. japonicus is characteristic in the lack of an exopod on the second maxilliped. In Spongicola and Paraspongicola , both exopods on the second and third maxilliped are well developed,flagellum-like.The lack of an exopod on the third maxilliped,which is considered to be apomorphic, links these two species to Spongicoloides and Spongiocaris (see Saito & Takeda 2003). The quadrangular shape of the telson, an apomorphic character, is also shared by these two species, Spongicoloides and Spongiocaris ( Saito & Takeda 2003) . Until full assessement of the systematic position of these two species will be made in a separate paper in progress, these two species are provisionally referred to Spongicola .

Figures

FIG. 2.— Spongicola venustus de Haan,1844,♀ 6.8 mm,Ushibuka,western Kyushu,Japan (CBM-ZC 977),left mouth parts:A, mandible, outer view; B, same, mesial view (basal article of palp hidden); C, maxillule, outer view; inset, endopod, lateral view; D, maxilla, outer view; E, first maxilliped, outer view; F, second maxilliped,outer view; G, same, coxa, basis and ischium, inner view;H, coxa and basis of third maxilliped, lateral view (arrow indicates exopod).