Stratiotes tuberculatus ( Whitelegge, 1900 ) Whitelegge, 1900

Rahayu, Dwi Listyo, 2005, Additions to the Indonesian fauna of the hermit crab genus Pseudopaguristes McLaughlin and a further division of the genus Paguristes Dana (Crustacea: Decapoda: Paguroidea: Diogenidae), Zootaxa 831, pp. 1-42 : 6-12

Stratiotes tuberculatus ( Whitelegge, 1900) n. comb. ( Figs. 1–3 )

Clibanarius sp. — Whitelegge, 1889: 232; McCulloch, 1913: 344.

Paguristes tuberculatus Whitelegge, 1900: 169 , figs. 1, 1A; McCulloch, 1913: 343, fig. 51; Hale, 1927: 90; Morgan, 1989: 395, fig. 1b; Davie, 2002: 56.

Material examined. 2 males, 1.7, 2.3 mm, Kai Islands, Siboga , stn 260, 05°36.5'S, 132°55.2'E, 90 m, 16–18 Dec 1899 ( ZMA).

Description. Biserial phyllobranchiae. Shield ( Fig.1 ) as long or longer than broad; lateral margins sloping or weakly terraced, spinulose, or with prominent spine. Rostrum broadly triangular, not overreaching level of lateral projections. Lateral projections triangular, with marginal or submarginal small spine. Branchiostegites each with row of very small spines on dorsal margin in distal half. Ocular peduncles slender to moderately stout, 0.6–0.8 length of shield; corneal diameter 0.2–0.4 of peduncular length; ocular acicles elongate, very slender, terminating acutely, often with moderately long, plumose setae. Antennular peduncles overreaching distal margins of corneas by 0.2–0.3 length of ultimate segments; basal segment with acute spine dorsolaterally. Antennal peduncles reaching nearly to or slightly overreaching distal margins of corneas; fifth and fourth segments unarmed; third segment unarmed or with spine at ventrodistal angle; second segment with dorsolateral distal angle produced, terminating in prominent simple or bifid spine, subdistal spine frequently present on lateral margin, dorsomesial distal angle with small spine; first segment unarmed. Antennal acicle reaching to or slightly beyond proximal margin of ultimate peduncular segment, terminating in prominent bifid spine, mesial margin with 2– 4 spines, lateral margin usually with 1 or 2 small spines. Antennal flagellum longer than carapace, each article with long, paired setae ventrally.

Chelipeds unequal and dissimilar, left cheliped much larger; carpus and chela of both articulating obliquely with merus, putting dorsal surfaces in lateral positions relative to body axis. Left cheliped ( Fig.2 a–c) with row of minute spinules or granules on ventromesial margin of ischium. Merus with 1 spine at dorsodistal margin, dorsal margin with spines or spinulose protuberances distally, row of low, sometimes spinulose protuberances and tufts of plumose setae proximally; lateral face with scattered small tubercles, at least in lower half, and tufts of plumose setae in dorsal half, distal margin with row of small spines in dorsal half, ventrolateral margin with row of often corneous­tipped spines; ventromesial margin with row of much more prominent, corneous­tipped spines, mesial face glabrous; ventral surface with moderately long plumose setae. Carpus with row of conical, sometimes corneous­tipped spines on upper margin; outer surface with numerous, but not closely­packed, smaller spines, forming longitudinal row in upper half, distal margin with row of small conical spines, 1 prominent spine at lower distal angle; inner surface with scattered low tubercles, lower distal margin with few plumose setae. Palm with single to double row of conical or tuberculate spines on upper margin and additional row adjacent to upper margin; outer surface with few individual, conical or tuberculate spines proximally and 2 or 3 longitudinal rows of clusters of 2 to several conical or elongate blunt or spiniform tubercles, lower row extending onto fixed finger on weakly elevated broad ridge; lower margin with 1–3 irregular rows of tubercles and tufts of moderately long, plumose setae; inner and lower surfaces with scattered low protuberances and sparse tufts of plumose setae. Dactyl approximately equal to length of palm; upper surface with irregular double row of conical or tuberculate spines and tufts of moderately long, plumose setae; outer surface with prominent longitudinal sulcus, often flanked dorsally and/or ventrally with few small tubercles; inner surface with row of small, conical spines and tufts of plumose setae dorsally, row of low protuberances and tufts of plumose setae ventrally; cutting edge with row of small, calcareous teeth, terminating in small calcareous claw; no hiatus between dactyl and fixed finger.

Right cheliped ( Fig. 2 d, e) with row of widely­spaced spinules or tubercles on ventromesial margin of ischium. Merus with 1 prominent spine at dorsodistal margin and slightly smaller subdistal spine, both partially obscured by long, plumose setae, remainder of dorsal margin with row of tiny spinules or small spines concealed by long, plumose setae; mesial face unarmed, ventromesial margin with long, plumose setae not obscuring row of small spines; lateral face with few scattered spinules, ventrolateral margin with few long, plumose setae and row of very small spines or spinules; ventral surface unarmed. Carpus with row of spines on upper margin increasing in size distally and partially obscured by long, plumose setae; outer face with row of small spines in upper half and 1 to several spinules in lower half; inner surface with few scattered setae. Palm with row of 3– 5 moderately small spines on upper margin; outer surface convex, with 4 or 5 irregular longitudinal rows of small spines partially obscured by long plumose setae, particularly in upper half, lower with 2 rows extending nearly to tip of fixed finger; inner surface of palm and fixed finger with widely­spaced tufts of short setae; cutting edge with row of very small calcareous teeth, terminating in corneous claw and with 1 or 2 adjacent corneous spines on lower margin. Dactyl with row of small spines on upper margin, at least partially obscured by long, plumose setae; outer surface with irregular short row of spinules accompanied by plumose setae; inner surface with few short setae; cutting edge with central longitudinal groove and few corneous teeth distally, terminating in small corneous claw.

Second and third pereopods ( Fig. 3 a–c) with left third dissimilar. Ischia of second pereopods each with 1 or 2 spinules on ventromesial margin; ischium of right third unarmed. Meri of second pereopods each with dorsal row of spinules and long plumose setae, ventral margins each with row of small spines; merus of third right with spinules or spinulose protuberances and long setae on dorsal margin, ventral margin with long, plumose setae and small spine at ventrolateral distal angle. Carpi each with dorsal row of spines partially concealed by long, plumose setae; spines of third right smallest. Propodi of second pereopods each with dorsal row of small spines and ventral row of spiniform setae, all obscured by tufts of long, plumose setae; propodus of third right with only plumose setae dorsally and ventrally. Dactyls of second and right third slightly longer than propodi; dorsal surfaces of each with row of very small spiniform setae obscured by long plumose setae; ventral margins each with row of small spiniform setae, also concealed by tufts of long, plumose setae; mesial and lateral faces of dactyl of second pereopods each with faint longitudinal sulcus; mesial and lateral faces of right third convex.

Left third pereopod ( Fig. 3 b) with ischium unarmed. Merus with row of very small spines or spinules on dorsal surface concealed by long, plumose setae; ventrolateral distal angle with small spine, ventral margin with long plumose setae. Carpus with small spine at dorsodistal margin and row of spinules on dorsal surface; lateral face with faint longitudinal sulcus in dorsal half. Propodus with minutely spinulose dorsal surface and long, plumose setae; lateral face with broad longitudinal sulcus flanked dorsally by row of very small spines and ventrally by row of blunt or subacute tooth­like spines; ventral surface with long plumose setae and row of tiny spinules, at least proximally. Dactyl longer than propodus; dorsal surface with 1 or 2 irregular rows of minute spinules and long, plumose setae; lateral face with broad longitudinal sulcus, flanked dorsally by row of minute spinules and ventrally by row of acute and/or blunt tooth­like spines, ventral surface spinulose, at least proximally, but armature frequently masked by long, plumose setae; mesial face with faint longitudinal sulcus. Fourth pereopod ( Fig. 3 d) with small preungual process.

Male first pleopods ( Fig. 3 e, f) robust; inferior lamella obtusely triangular, distal margin with row of small hook­like spines. External lobe elongate, separated from internal lobe by deep narrow cleft; internal lobe broad. No brood pouch developed in ovigerous females, but tuft of long, plumose setae present posterior to egg­bearing fourth pleopod (McLaughlin, pers. comm.).

Telson ( Fig. 3 g) with posterior lobes asymmetrical, right smaller; right terminal margin with few setae and 2 to several spinules, not extending onto lateral margin, left with setae and 6 or more stronger spinules, often extending onto lateral margin.

Color. Antennae and ambulatory legs annulated with narrow reddish bands. Chelae bright red, tips of fingers of larger hand white, body and limbs scantly clothed with brownish setae (after Whitelegge 1900).

Habitat. Reported from sand and pebble bottom in New South Wales. In southwestern Australian, Morgan (1989) recorded this species from soft substrates, usually associated with seagrass meadows. McCulloch (1913) reported that the shells of this species were almost always accompanied by polyzoan colonies; however, Morgan (1989) did not find such an association in specimens collected in Western Australia. In Indonesia this species was collected from sand substrate and shell fragments.

Distribution. New South Wales, Western Australia, and now from the Kai Islands, Indonesia; subtidal to 90 m.

Remarks. The description provided above is based in part on the two males collected during the Siboga Expedition , and in part on information provided on the type series by P. McLaughlin. The grossly unequal chelipeds with the tuberculate armature of the left chela and the dissimilar third pereopod set this species apart from the other species now assigned to Stratiotes . Until its present recognition, S. tuberculatus n. comb. was believed to be endemic to Tasmania, southern and western Australia at depths up to 50 m ( Morgan 1989). Its presence in the Kai Islands represents both range and depth extensions.

Figures

FIGURE 1. Stratiotes tuberculatus (Whitelegge, 1900) n. comb., male, 2.3 mm (ZMA). Shield and cephalic appendages, setae partially omitted. Scale equals 1 mm.

FIGURE 2. Stratiotes tuberculatus (Whitelegge, 1900) n. comb., male, 2.3 mm (ZMA): a – c, left cheliped, setae omitted; d, e, right cheliped, setae ommited; a, dorsolateral view; b, e, inner view; c, d, outer view. Scale equals 1 mm.

FIGURE 3. Stratiotes tuberculatus (Whitelegge, 1900) n. comb. male, 2.3 mm (ZMA): a, left second pereopod, setae omitted; b, left third pereopod, setae omitted; c right third pereopod, setae omitted; d, left fourth pereopod, setae omitted; e, f, right first pleopod; g, telson, setae omitted; a – d, lateral view; e, external view; f, internal view. Scale equals 1 mm.