Paguristes simplex, Rahayu & McLAUGHLIN, 2006

Rahayu, Dwi Listyo & McLAUGHLIN, Patsy A., 2006, Clarifications of the identities of Paguristes balanophilus Alcock, 1905 and P. calvus Alcock, 1905 (Crustacea, Decapoda, Anomura, Paguroidea, Diogenidae), and the description of another broadly distributed new species, Zoosystema 28 (4), pp. 865-886 : 879-884

Paguristes simplex n. sp.

( Figs 6 ; 7 )

TYPE MATERIAL. — Madagascar. Vauban , stn CH 14 , 12°43.3’S, 48°15.7’E, 245-255 m, 15.IV.1971, coll. A. Crosnier, ♂ holotype 6 mm ( MNHN) ; same data as holotype, 3 ♂♂ paratypes 5.8-6.0 mm ( MNHN) .

Western Australia. 114 nautical miles north of Point Headland, 18°25’S, 118°22’E, 201 m, 2.IV.1982, 5 ♂♂ paratypes 4.6-7.4 mm, 5 ♀♀ paratypes 2.9-4.7 mm, 2 ovig. ♀♀ paratypes 4.1, 5.3 mm ( WAM C16715).

ETYMOLOGY. — From the Latin simplex meaning one and referring to the single row of primary tubercles or spines on the mesial face of the dactyl of each cheliped.

TYPE LOCALITY. — Madagascar, Vauban, stn CH 14, 12°43.3’S, 48°15.7’E, 245- 255 m.

DISTRIBUTION. — Madagascar; northern Western Australia.

DESCRIPTION

Gills deeply quadriserial; branchiostegites each with short row of very small to tiny spinules on dorsal margin distally, anterior margins each with 1 or 2 spinules or very small spines. Shield ( Fig. 6A ) slightly longer than broad; anterolateral margins sloping; anterior margin between rostrum and lateral projections concave; posterior margin roundly truncate; dorsal surface with very few spinules marginally and very sparse setae. Lateral projections triangular, subacute, with or without terminal spinule. Rostrum triangular, reaching beyond bases of ocular acicles, unarmed or with terminal spinule and with marginal short setae.

Ocular peduncles unequal, left longest, 0.6-0.9 length of shield; dorsal surfaces each with sparse row of moderately long setae; corneal diameter 0.1-0.3 peduncular length. Ocular acicles acutely triangular, each with small terminal spine; separated basally by approximately basal width of one acicle.

Antennular peduncles, when fully extended, not quite reaching left distal corneal margin to exceeding margin by 0.3 length of ultimate segment. Ultimate and penultimate segments with few moderately short setae. Basal segment with acute spine on dorsolateral margin of statocyst lobe and 1 spine at ventromesial distal angle.

Antennal peduncles reaching distal 0.2-0.3 of left ocular peduncle; fifth segment unarmed; fourth segment with small dorsodistal spine; third segment with prominent ventrodistal spine; second segment with dorsolateral distal angle produced, terminating in simple or bifid spine; dorsomesial distal angle with small to moderately large spine; first segment with small spine on ventrodistal margin. Antennal acicle reaching 0.5-0.6 of left ocular peduncle; with bifid terminal spine; mesial margin with 3-5 spines, lateral margin with 2 spines in distal half. Antennal flagellum shorter than carapace; each article with 1-4 long and 1 or 2 short setae.

Third maxilliped with 1 small spine on ventrodistal margin of ischium; dorsodistal margin of merus unarmed, ventral margin with 3-5 spines.

Chelipeds subequal; left ( Fig. 7A, B ) or right slightly larger; armature generally similar; dactyl and fixed finger without hiatus. Dactyl slightly longer than palm; dorsomesial margin with row of moderately large spines, decreasing in size distally and accompanied by sparse tufts of moderately long setae, adjacent dorsal surface with row of tuberculate spines and sparse tufts of setae; mesial face ( Fig. 7C ) with 1 row of moderately large tuberculate spines or spinulose tubercles dorsally, occasionally row of widely-spaced protuberances or tubercles ventrally; cutting edge with row of small calcareous teeth in proximal 0.4-0.6, row of corneous teeth distally; terminating in small corneous claw, sometimes slightly overlapped by fixed finger. Palm approximately equal to length of carpus; dorsomesial margin with row of 4 or 5 prominent spines and tufts of setae, dorsolateral margin not delimited; weakly convex dorsal surface with several irregular rows of somewhat smaller tuberculate spines and sparse tufts of long setae, few rows extending nearly entire length of fixed finger; mesial face with scattered small tubercles or spinules, occasionally 1 or 2 irregular rows of 3-5 tubercles; ventral surface with few tubercles and sparse tufts of long setae, tubercles most prominent on fixed finger; cutting edge of fixed finger with row of small calcareous teeth; terminating in small corneous claw. Carpus 0.5-0.6 length of merus; dorsomesial margin with row of 5 or 6 prominent, often corneous-tipped spines, dorsal surface with numerous spines, largest forming irregular median row, and sparse tufts of long setae, dorsolateral margin only weakly delimited by 1 or 2 irregular rows of spines; lateral face with irregular rows of small spines; mesial face with few tubercles or protuberances. Merus with few spines, sometimes corneous-tipped, on distal margin; dorsal margin with row of transverse, spinose or spinulose ridges accompanied by tufts of long setae; ventromesial margin with row of small spines and long setae; ventrolateral margin with few small spines in distal 0.3-0.5. Ischium with row of minute tubercles on ventromesial margin.

Second ( Fig. 7D, F ) and third pereopods ( Fig. 7E ) with dactyls 1.4-1.9 length of propodi; dorsal margins each with row of tufts of moderately long, stiff setae, few very small spines proximally on second pereopods; lateral faces each with weak longitudinal sulcus, at least proximally, and few to row of sparse tufts of short setae dorsally or medially; mesial faces each with weak longitudinal sulcus and irregular, transverse rows of short setae, few to irregular row of tiny spinules ventrally in larger specimens; ventral margins each with row of 15-18 corneous spines. Propodi 1.1-1.4 length of carpi; dorsal margins each with row of few spines accompanied by tufts of moderately long setae on second pereopods, third with row of very small spinules or only tufts of moderately long setae, sometimes arising from low protuberances; mesial faces with few fine, moderately long setae; angular lateral surfaces each with dorsal row of low protuberances or spinules and sparse tufts of setae, row of sparse setae medially; ventral surfaces each with row of low, sometimes spinulose protuberances and sparse tufts of setae. Carpi 0.6-0.8 length of meri; dorsal margins each with irregular row of moderately large spines (second) or dorsodistal spine and sometimes row of very small spines (third); lateral faces each with weak longitudinal sulcus and frequently small spine dorsally; ventral surfaces with few tufts of short setae. Meri each with dorsal row of low protuberances and tufts of moderately short setae; ventral margins of second pereopods each with row of small spines in distal half and tufts of moderately short setae, third unarmed but with sparse tufts of setae. Ischia unarmed but with sparse setae. Fourth pereopods ( Fig. 6B ) each with small preungual process at base of claw.

Male first pleopods ( Fig. 6C, D ) each with row of moderately short setae on lateral margin of inferior lamella, row of large, slender hooked spines on distal margin, continued down inner margin and decreasing in size; external lobe reaching distal margin of inferior lamella; internal lobe short, with long marginal setae extending onto inner face. Second pleopods ( Fig. 6E ) with basal segment naked, distal segment with tuft of setae distally on endopod, appendix masculina with row of long marginal setae. Female gonopores paired; paired first pleopods well developed, 2-segmented. Brood pouch ( Fig. 6F ) subovate, with marginal plumose setae. Tergites of left pleonal somites 2-4 each with thickened margin and row of long, dense, plumose setae. Telson ( Fig. 6G ) with deep lateral incisions separating anterior and posterior lobes; asymmetrical posterior lobes separated by very shallow, slit-like median cleft; left lobe usually appreciably elongate, both lobes subtriangular with rounded apices, terminal and lateral margins each with row of long setae.

Colour (in preservative)

Most colour lost; however, ocular peduncles retain a solid tint of colour.

HABITAT

Not reported.

VARIATION

Variation that appears to be growth related may be seen in the strength of the armature of the ambulatory legs. The smallest female has fewer spines developed on the dorsal margins of the dactyls of the second pereopods; only a row of very low protuberances is present on the dorsolateral surface of each propodus, and a row of spines is present only on the carpus of each second pereopod. In the males, all of which are larger, and the largest and ovigerous female, the spines on the dorsal margins of the dactyls of the second pereopods are more numerous and better developed; the propodi each have a row of spines or spinules rather than low protuberances on each dorsolateral face; and the carpi of the third pereopods each has a row of spinules on the dorsal surface in addition to the large dorsodistal spine. The brood pouch of the largest female is appreciably broader than that of the smallest, but whether this is related to animal size or an egg bearing condition is not known.

AFFINITIES

Paguristes simplex n. sp. appears morphologically most closely allied to P. pusillus Henderson, 1896 and P. jalur Morgan, 1992 , sharing with those species the single row of spines or tubercles on the mesial face of each dactyl of the chelipeds and the tendency for the dactyls of the second pereopods, at least, to develop sulci on the mesial and/or lateral faces. The differences between P. simplex n. sp. and P. pusillus lie in the shape of the telson and the female brood pouch. The posterior lobes of the telson of P. pusillus only slightly asymmetrical and separated by V-shaped median cleft while in P. simplex n. sp. the posterior lobes are strongly asymmetrical and separated by shallow median cleft. Although the shape of brood pouch can be variable as shown by McLaughlin (2004) for P. puniceus Henderson, 1896 , the females of P. simplex n. sp. have quite consistence shape of the brood pouch which is subovate with marginal plumose setae, while P. pusillus has large, fan-shaped brood pouch ( McLaughlin & Rahayu 2005).

Morgan (1992) related P. jalur to P. runyanae Haig & Ball, 1988 , and the characters shared by P. simplex n. sp. and P. jalur are similarly shared by

D

E

P. runyanae . Of those cited by Morgan (1992) to differentiate between the latter two species, most were shown by McLaughlin (2004) to be growth related. However, for specimens of approximately comparable shield lengths, the ocular peduncles of Haig & Ball’s (1988) taxon are considerably longer and slenderer than those of either P. jalur or P. simplex n. sp. Haig & Ball (1988) did not describe the gill lamellae of P. runyanae , but those of P. jalur are only distally quadriserial, whereas the lamellae of P. simplex n. sp. are deeply quadriserial. Neither Morgan (1992) nor Haig & Ball (1988) specified the number of spines on the ventral margins of the dactyls of the ambulatory legs, but in the illustrated specimens of both species the number did not exceed 12. The smallest specimen of P. simplex n. sp. in the type series is smaller than either the specimen of P. jalur illustrated by Morgan (1992: fig. 2C, D) or of P.runyanae by Haig & Ball (1988: figs 6F, 7A). Nevertheless, the number of spines on the ventral margins of the dactyls of P. simplex n. sp. is 17, with the range among the type series being 15 to 18.

Superficially, P. simplex n. sp. is also very similar to P. palythophilus Ortmann, 1892 . These two taxa can be distinguished by the presence, in the latter species, of three to five rows of spines or tubercles on the mesial faces of the dactyls of the chelipeds and the relatively smooth mesial faces of the palms that are usually armed with only two or three large tubercles dorsally. Additionally, in P. palythophilus the cutting edge of the dactyl is armed with two or three large calcareous teeth proximally, and rostrum is usually longer.

Figures

FIG. 6. — Paguristes simplex n. sp.: A-E, holotype, ♂ 6 mm; F, paratype,♀ 4.3 mm; A, shield and cephalic appendages,setae partially omitted;B, left fourth pereopod,setae omitted;C, male first pleopod,dorsal view, setae partially omitted; D, male first pleopod,mesial view, setae omitted; E, male second pleopod, dorsal view, setae partially omitted; F, brood pouch. Scale bars: 1 mm.

FIG. 7. — Paguristes simplex n. sp., holotype, ♂ 6 mm: A, left cheliped, dorsal view; B, merus of left cheliped, lateral view; C, dactyl of left cheliped, mesial view, setae partially omitted; D, left second pereopod, lateral view; E, left third pereopod, lateral view; F, left second pereopod, mesial view, setae partially omitted; G, telson. Scale bars: 1 mm.