Stratiotes abbreviatus ( Dechancé, 1963 ) Rahayu, 2007

Rahayu, Dwi Listyo, 2007, The hermit crabs Paguristes Dana, 1851 s. l. (Crustacea, Decapoda, Anomura, Diogenidae) from the western Indian Ocean, Zoosystema 29 (3), pp. 515-534 : 530-533

Stratiotes abbreviatus ( Dechancé, 1963) n. comb.

( Fig. 5 )

Paguristes jousseaumei var. perspicax – Nobili 1906: 87 (pro parte).

? Paguristes pusillus var. – Nobili 1906: 88.

Paguristes abbreviatus Dechancé, 1963: 297 , figs 3, 6, 9.

MATERIAL EXAMINED. — Bahrein coast. Expedition J. Bonnier and Ch. Pérez on Arabian coasts, stn LVI, holotype, ♀ ovig. (3. 8 mm) (MNHN-Pg 1525). — Same locality as holotype, 2 ♀♀ ovig, (2.6-3.4 mm) (MNHN- Pg 1524).

Madagascar. Nosy Bé, 1 ♀ (2 mm) (MNHN-Pg 1526). — Nosy Bé, 15-22 m, 15.I.1971, coll. P. Laboute, 1 ♀ (1.9 mm). — Tuléar, Grand récif, stn 97, 1.XII.1965, coll. Thomassin, 1 ♀ ovig. (3.2 mm). — Tuléar, stn 369, coll. Thomassin, 1 ♂ (1.8 mm). — Tuléar, stn 435, coll. Thomassin, 1 ♀ ovig. (3.8 mm).

DISTRIBUTION. — Bahrein coast, Nosy Bé and Tuléar, Madagascar.

REDESCRIPTION

Twelve pairs of biserial gills; branchiostegites each with two or three spinules on distal margin concealed by dense setae. Shield longer than broad, dorsal surface with several tubercles or subacute spine and several tuft of setae. Rostrum broadly triangular, slightly overreaching bases of ocular acicles, terminating acutely. Lateral projections as long as rostrum, acutely triangular, each with terminal spine.

Left ocular peduncle slightly longer than right, 0.6 of shield length, slender, swollen basally, narrowing distally to small, rounded cornea; dorsomesial and dorsolateral surfaces of peduncles each with row of dense setae on half proximally; corneal diameter 0.1 of peduncular length. Ocular acicles subquadrate, approximate, terminal margin with five or six spines, decreasing in size laterally.

Antennular peduncles, when fully extended, exceeding corneas by 0.2 of length of ultimate segments; basal segment with small median spine on lateral margin.

Antennal peduncles reaching 0.6 of ocular peduncles; fifth and fourth segments unarmed, with few scattered setae; third segment with ventrodistal margin rounded, three to six spinules on terminal margin and few scattered setae; second segment with dorsolateral distal angle produced, terminating in bifid spine, lateral margin with two spines, lateral and ventral surfaces with sparse setae, dorsomesial distal angle with two small spines, mesial margin with few setae; first segment with one distal spine dorsolaterally and few long setae. Antennal acicle reaching half length of fifth peduncular segment, terminating in prominent bifid spine; three spines on lateral margin, three or four spines on mesial margin and dense and long plumose setae concealing armature. Antennal flagellum shorter than shield; articles each with two to four moderately long setae, slightly more numerous setae distally.

Chelipeds subequal, left slightly larger than right, armament similar. Left cheliped ( Fig. 5A, B ) with dactyl almost twice length of palm; dorsomesial margin delimited by row of large corneous-tipped spines, with row of short, stiff setae circumscribing each spine, larger spines proximally, becoming smaller distally; dorsal surface with row of small, corneous-tipped spines, each circumscribed by row of short stiff setae; mesial face ( Fig. 5C ) with irregular rows of low protuberances, each circumscribed by row of short, stiff setae; cutting edge with row of moderately small calcareous teeth on proximal half, distal half with small corneous teeth, terminating in corneous claw; narrow hiatus proximally between dactyl and fixed finger. Palm with row of four large corneous-tipped spines on dorsomesial margin, row of short stiff setae circumscribing each spine, convex dorsal surface with irregular rows of large corneous-tipped spines, each circumscribed by row of short stiff setae, rounded dorsolateral margin with row of large corneous-tipped spines, becoming less prominent distally on fixed finger, each spine also circumscribed by row of short stiff setae; lateral face of palm and fixed finger with irregular row of spinulose tubercles, each circumscribed by row of short stiff setae, ventral surface with row of spinulose tubercles, decreasing in size on fixed finger and accompanied by tufts of setae; mesial face with few protuberances and tufts of short stiff setae; cutting edge of fixed finger with row of moderately large calcareous teeth, terminating in small corneous claw. Carpus with row of four prominent, corneous-tipped spines on dorsomesial margin, each accompanied by row of short, stiff setae; dorsolateral margin delimited by row of six prominent corneous-tipped spines accompanied by row of stiff setae, dorsal surface with row of tuberculate spines near dorsomesial margin, each also circumscribed by row of short and stiff setae; dorsodistal margin with row of corneous-tipped spinules; mesial face with longitudinal row of tufts of short stiff setae. Merus with one prominent spine and row of long stiff setae on distal margin extending onto lateral and mesial faces, dorsal surface with subdistal short, transverse row of spinules extending onto lateral and mesial faces, remainder of dorsal margin with row of prominent spines becoming smaller proximally, each spine accompanied by tuft of short, stiff setae; mesial face smooth, ventromesial margin with row of small, spinulose tubercles and sparse tufts of setae; lateral face spinulose, at least dorsally, ventrolateral margin with row of tuberculate spines and long plumose setae. Ischium with row of small tubercles on ventromesial margin and sparse long setae. Right cheliped slightly smaller than left, armature similar but with less prominent spines.

Left second and third pereopods slightly longer than right. Dactyls slightly longer than propodi, dorsal margins each with row of dense setae, ventral margins each with five to seven corneous spines (second) or five to 10 corneous spines (third) concealed by dense plumose setae. Propodi of second pereopods each with row of prominent, corneous-tipped spines concealed by stiff, sometimes plumose, setae on dorsal margin; dorsal surface of third unarmed but with dense, sometimes plumose, setae; mesial faces each with row of tufts of short setae medially and transverse rows of tufts of short setae (second), or long plumose setae (third) on mesioventral and ventral surfaces, and row of tufts of short setae near dorsal margin; lateral faces of second each with row of tufts of short, stiff setae medially; lateral faces of third each with row of spinules near ventral margin, accompanied by tufts of setae. Carpi of second pereopods each with irregular row of seven or eight prominent, corneous-tipped spines on dorsal margin, concealed by dense plumose setae. Third pereopods each with prominent distal spine and also dense plumose setae on dorsal margin; mesial faces each with row of tuft of plumose setae; lateral face each with longitudinal sulcus accompanied by row of tufts of dense plumose setae and with two or three distal spines, few tufts of setae laterad of sulcus; ventral surface with dense long plumose setae distally. Meri each with dorsal row of low protuberance, few spines and long, dense plumose setae proximally; ventral margins each with row of dense long plumose setae, mesioventral margin with several small corneous-tipped spines (second) or unarmed (third). Ischia each with one or two spinules on ventromesial margin distally and dense plumose setae. Fourth pereopods each with preungual process at base of claw, no distal spine on dorsal margin of carpus.

Male with paired first and second pleopods. Male first pleopods ( Fig. 5D, E ) each with tuft of setae on superior mesial angle of basal lobe; distal margin of inferior lamella unarmed; external lobe overreaching inferior lamella, internal lobe short, with marginal setae. Second pleopods ( Fig. 5F, G ) each with basal segment glabrous; endopod with row of moderately long setae on mesial margin, distal angle with tuft of stiff setae; appendix masculina with long setae on distal margin and inferior surface. Female with single gonopore on coxa of third left pereopod, first pleopod 2-segmented. Brood pouch small, obtusely triangular with marginal long plumose setae. Eggs small, attached to second and third pleopods.

Telson ( Fig. 5H ) with moderately deep lateral incisions separating anterior and posterior portions; posterior lobes asymmetrical, separated by small, V-shaped median cleft, terminal margins each armed with three to six spines.

VARIATION

In small female specimens (SL ≤ 2.6 mm) the setae on chelipeds and pereopods are less dense; and the ventral margins of the dactyls of the second and third pereopods each have four to 10 corneous spines. In

male specimens the terminal margins of posterior lobes of telson have five or six spines.

REMARKS

Stratiotes abbreviatus was described by Dechancé (1963) as Paguristes abbreviatus . Rahayu (2005) revised Paguristes s.l. and transferred to Stratiotes those species with 12 pairs of gills. Examination of Dechancé’s taxon has shown that it has 12 pairs of biserial gills; therefore it is also transferred to Stratiotes . The redescription herein included is based on the holotype, paratypes and the specimens collected by Thomassin in Tuléar, Madagascar.

Differences were observed in setation between the types and the specimens reported herein. In the holotype and paratypes, the setation of the chelipeds and pereopods is much reduced; the specimens are almost glabrous. It is probable that the setae were removed during a previous study in order to see the armament clearly. On the specimens from Tuléar the setae were dense and matted by mud. When the mud was removed, the plumose setae and row of stiff setae circumscribing each spine were revealed. The shape of shield and cephalic appendages and the armament of the chelipeds and pereopods showed that they all belong to the same species.

The female brood pouch, although small, is present in the females examined, while Dechancé (1963: 298) mentioned that types were “sans repli membraneux sur l’abdomen”. The holotype and paratypes have broken or damaged pleons, and it is probable that the brood pouches are missing.

Figures

FIG. 5. — Stratiotes abbreviatus (Dechancé, 1963) n. comb., ♀, 3.8 mm: A, left cheliped, mesial view; B, left cheliped, dorsal view; C, dactyl of left cheliped, mesial face; D, male first pleopod, external view; E, same, internal view; F, second male pleopod, internal view; G, same, external view; H, telson, dorsal view. Setae partially omitted. Scale bars: 1 mm.