Paguristes alcocki, Mclaughlin, Patsy A. & Rahayu, Dwi Listyo, 2005

Mclaughlin, Patsy A. & Rahayu, Dwi Listyo, 2005, Two new species of Paguristes sensu stricto (Decapoda: Anomura: Paguroidea: Diogenidae) and a review of Paguristes pusillus Henderson, Zootaxa 1083, pp. 37-62 : 40-49

Paguristes alcocki n. sp. ( Figs 1–3 )

? Paguristes ? ciliatus— Alcock 1905: 34 . [Not Paguristes ciliatus ( Heller, 1862) ].

Paguristes ciliatus .— Gordan, 1956: 321 [in part; literature].

? Paguristes ciliatus .— Haig & Ball, 1988: 176; Wang, 1992: 59 (list); Wang, 1994: 568; Rahayu, 2000: 392. Not Paguristes ciliatus ( Heller, 1862) .

Paguristes ciliatus .— Wang, 1983: 50 (in part, not pl. 1: fig. 2). Not Paguristes ciliatus Heller, 1892 (see Remarks).

Type material. Western Australia: holotype male (7.8 mm), 33 nautical miles N of Rosemary Island, 19°55’S, 116°36’E, 58 m, 29 Nov 1982, WAM C29554. Paratypes, 33 nautical miles N of Rosemary Island, 19°55’S, 116°36’E, 58 m, 29 Nov 1982, 2 males (6.3, 7.5 mm), WAM C16862, C16493; 39 nautical miles north of Enderby Island, 19°58.1’S, 116°27.9’E, 58–59 m, 28 Sep 1982, 1 ovig. female (5.5 mm), WAM C16751.

Indonesia: Wamsoi Lagoon, Padaido, Irian Jaya, 57–91 m, 0 4 Feb 1956, 1 male (7.2 mm), RMNH. Philippine Islands: Panglao Expedition, stn L43, off Pamilacan Island, 09°30’N, 123°05’E, 60 m, 0 2 Jul 2004, 1 male (8.6 mm), NMP.

Description. Thirteen pairs of quadriserial gills; branchiostegites each with few spinules on distal margin and dorsal margin distally, concealed by moderately dense setae. Shield ( Figs 1 a, 3) longer than broad; dorsal surface with few tubercles or subacute spines and sparse covering of setae laterally, few scattered tufts centrally. Rostrum slender, elongate, reaching beyond bases of ocular acicles and considerably overreaching lateral projections, but broader in female, terminating acutely or with tiny spinule. Lateral projections triangular, each with tiny terminal spine.

Ocular peduncles 0.7 to as long as shield length, slender, each with sparse tuft of setae basally; corneal diameter 0.1 peduncular length. Ocular acicles subtriangular, terminating acutely or in simple terminal spine; separated by less than basal width of 1 acicle.

Antennular peduncles, when fully extended, not reaching to bases of corneas; basal segment with small spine on lateral face of statocyst lobe.

Antennal peduncles not exceeding 0.5 of ocular peduncles; fifth segment with few scattered setae; fourth segment with small dorsodistal spine; third segment with moderately dense setae laterally, ventrodistal margin drawn out into acute spine; second segment with dorsolateral distal angle produced, terminating in bifid spine, lateral and ventral surfaces with dense long setae, dorsomesial distal angle with small spine, mesial margin with setae; first segment unarmed. Antennal acicle reaching to distal 0.2 or nearly to distal margin of fifth peduncular segment, terminating in prominent bifid spine; 2 spines on lateral margin, 1 or 2 spines on dorsal surface mesially and scattered setae not concealing armature. Antennal flagellum slightly shorter to longer than carapace; articles each with 1 or 2 short setae proximally, slightly more numerous setae distally.

Chelipeds subequal to unequal, somewhat dissimilar; left slightly to noticeably larger and more subovate. Left cheliped ( Figs 2 a, 3) with dactyl (missing in smallest Australian male paratype) 1.7 to twice length of palm; dorsomesial margin delimited only distally by short row of acute small spines, dorsal surface with numerous, scattered small tubercles and irregular row of slightly larger tuberculate spines mesiad of midline in males, closelypacked and somewhat flattened tubercles in female; mesial face ( Fig. 2 b) with ventroproximal unarmed area, remainder of surface with irregular, almost transverse, rows of small, sometimes corneous­capped, tubercles and small spines, obscured by covering of moderately short, dense setae; cutting edge with row of small calcareous teeth, terminating in small corneous claw; with or without very slight hiatus between dactyl and fixed finger. Palm with row of moderately small spines on dorsomesial margin, broader and multifid in female, convex dorsal surface with covering of flat, or slightly swollen, scale­like plates, each usually with 1–3 tiny, corneous­tipped spinules, dorsolateral margin with row of small tuberculate spines, becoming more prominent and acute distally on fixed finger and concealed by moderately dense long setae in males, but not distinctly delimited in female; mesial face with row of very small, sometimes spinulose, tubercles adjacent to distal margin and parallel, subdistal row of larger flattened tubercles, 1 additional large, flattened and corneous­capped tubercle dorsally in midline; lateral face of palm and fixed finger with scattered spinulose tubercles, ventral surface with irregular, transverse rows of spinulose tubercles, decreasing in size on fixed finger and accompanied by tufts of setae. Carpus with row of moderately prominent spines on dorsomesial margin, distal margin with row of small, tuberculate spines, extending onto lateral face; dorsolateral margin not delimited, dorsal and lateral surfaces with numerous, but not dense, small tuberculate spines, 1 larger spine in midline proximally; mesial face with parallel distal and subdistal row of small spinulose tubercles or projections, partially obscured by tufts of long setae, remainder of surface with low, spinulose and corneous­capped tubercles, continued onto ventral surface and accompanied by tufts of setae. Merus with row of spines on distal margin extending onto lateral and mesial faces, dorsal surface with subdistal short, transverse row of spines also extending onto lateral and mesial faces, remainder of dorsal margin with row of spines decreasing in size proximally and becoming obsolete; mesial face spinulose, ventromesial margin with double row of small, spinulose tubercles or tuberculate spines and dense tufts of setae; lateral face spinulose, at least ventrally, ventrolateral margin with double row of small, tuberculate spines obscured by long dense setae; ventral surface with covering of short, dense setae. Ischium with row of small tubercles on ventromesial margin concealed by long dense setae.

Right cheliped ( Figs 2 c, 3) with dactyl 1.7 to twice length of palm; dorsomesial margin with row of moderately small, corneous­tipped spines, decreasing in size distally; dorsal surface with numerous quite small, sometimes corneous­tipped, tuberculate spines; cutting edge with row of very small calcareous teeth in proximal 0.7, corneous teeth distally, terminating in small corneous claw; mesial face ( Fig. 2 d) with numerous corneous­capped tubercles, forming 2–4 irregular longitudinal rows proximally, 1 or 2 rows distally and scattered tufts of setae. Palm with row of 4–6 moderate to very prominent spines on dorsomesial margin, dorsolateral margin not delimited, dorsal surface of palm and fixed finger with irregular semi­transverse rows of small, tuberculate or flattened, sometimes corneous­tipped spines or tubercles, each often accompanied by circlet of very short setae, spination partially obscured dorsolaterally by dense short to moderately long setae; cutting edge of fixed finger with row of small calcareous teeth, terminating in small corneous claw; mesial face of palm with subdistal vertical row of low, large tubercles and tufts of setae, additional large tubercles in midline dorsally; ventral surface with numerous low protuberances and tufts of setae; lateral surface of palm and fixed finger with covering of spinulose or flattened tubercles and/or small, sometimes corneous­tipped spines, almost completely concealed by dense, moderately short setae. Carpus with row of prominent spines on dorsomesial margin, dorsodistal margin with row of spinules, extending onto lateral face; dorsolateral margin not delimited, dorsal surface and lateral face each with numerous small, tuberculate, sometimes corneous­tipped spines; mesial face tuberculate and with subdistal row of larger tuberculate spines partially concealed by tufts of dense setae; ventral surface weakly tuberculate and with distal tufts of dense setae. Merus with row of spines on distal margin extending onto lateral and mesial faces, dorsal surface with short, transverse row of subdistal spines also extending onto lateral face, remainder of dorsal surface with row of spines decreasing in size proximally and becoming obsolete; ventromesial margin with row of tuberculate spines and tufts of moderately long setae; lateral surface spinulose, ventrolateral margin with row of small spines distally becoming double to triple row of spinulose tubercles proximally, partially obscured by tufts of dense, moderately short setae; ventral surface with dense tufts of short setae. Ischium with row of tubercles and tufts of setae on ventromesial margin.

Second and third pereopods ( Figs 2 e–h, 3) differing somewhat in armature; right pereopods slightly longer than left. Dactyls 1.6–2.0 longer than propodi; dorsal margins each with row of corneous­tipped small spines (second) or very small spines or tubercles (third) and long, moderately stiff setae; ventral margins each with 11–22 corneous spines, concealed by long, stiff setae; lateral faces of second each with 1–3 rows of tufts of short setae and sometimes also weak longitudinal sulcus proximally, lateral faces of third each also with 1–3 rows of sparse tufts of short to moderate setae and occasionally corneous spinules and weak longitudinal sulcus proximally; mesial faces of second each with shallow sulcus in proximal half, ventral margin cut into row of weak, spiniform scutes, more tuberculate in female, mesial faces of third with 3 or 4 rows of corneous spinules and occasionally weak longitudinal sulcus. Propodi of second pereopods each with irregular row of prominent spines on dorsal surface partially obscured by tufts of long setae, third pereopods each with dorsal row of low protuberances and few small spines also partially concealed by tufts of setae; ventral margins of second pereopods each with row of small spines and tufts of setae, third with tufts of setae; mesial faces of second pereopods each with numerous scattered tubercles and short, transverse rows of setae ventrally; third with few faint protuberances and ventral short, transverse rows of sparse tufts; lateral faces of second pereopods each with weak median longitudinal sulcus and scattered tubercles dorsally, third with few scattered tufts of setae. Carpi each with shallow longitudinal sulcus on lateral face; second pereopods each with dorsal single or double row of prominent spines and tufts of long setae, third with prominent dorsodistal spine and small spines or protuberances and tufts of setae on remainder of dorsal surface; lateral faces of second pereopods each with additional cluster of small spines distally in dorsal half. Meri of second pereopods each with dorsal and ventral rows of small spines partially obscured by long setae, third unarmed, but with dense setae, particularly on ventral margins. Ischia unarmed but with dense dorsal and ventral setae. Fourth pereopods each with small preungual at base of claw; no dorsodistal spine on carpus.

Male first gonopods ( Fig. 1 b, c) each with tuft of setae on superior mesial angle of basal lobe; single row of small hook­like corneous spines on distal margin of inferior lamella; external lobe overreaching inferior lamella, internal lobe short, with marginal setae and moderately dense setal covering on inner surface. Second gonopods ( Fig 1 d) 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. Left pleopods 3–5 with exopods well developed; endopods very rudimentary. Female first pleopods ( Fig. 1 e) each with numerous moderately long setae on distal half of basal segment; distal segment with long marginal setae. Brood pouch large, fan­shaped with margin weakly scalloped and provided with fringe of long, plumose setae. Eggs numerous, moderately small, diameter of non­eyed eggs 0.9–1.1 mm.

Telson ( Fig. 1 f) with deep lateral incisions; median cleft small, shallow; posterior lobes markedly asymmetrical, terminal and lateral margins unarmed, but each with row of long setae.

Color in life. Shield mottled pink and darker reddish orange; ocular and antennular peduncles uniformly salmon pink, ocular acicles similar, but slightly lighter; antennal peduncles whitish­pink. Chelipeds with chelae orangish­pink with several whitish tubercles on mesial face; dorsal surfaces of carpi orangish­pink distally, with irregular median transverse whitish band, mottled pink, red and white proximally and whitish tubercles; meri orangish­red and white distally, subdistal, irregular patch of pinkish­white dorsally, predominantly red to red­orange in proximal halves; mesial faces each with prominent circular red patch dorsodistally, circumscribed by broad white ring, lateral faces each with similar, but somewhat less definitive patch. Second and third pereopods with dactyls predominantly orangish­red, each with whitish patch or band distally, narrow, irregular band proximally, and sometimes light colored patch dorsomesially ( Fig. 3 ); propodi, carpi and meri each with irregular narrow whitish band proximally and broader whitish band distally, median areas red with scattered white spots.

Alcock (1905) indicated that the color of his specimen of P.? ciliatus was similar to that of Paguristes balanophilus Alcock, 1905 , but that the shield was mottled­red. Coloration (in preservative) of P. balanophilus was reported by Alcock to be pinkishwhite with a well­defined orange patch on a violet field on both the mesial and lateral faces of the merus each cheliped, most distinctive on the mesial face.

Habitat. One of the Australian paratypes inhabited a shell entirely covered by a calcareous bryozoan.

Distribution. Know with certainty only from Western Australia, Indonesia and the Philippine Islands, but perhaps also from the South China Sea and Persian Gulf; 58 to possibly 110 m.

Etymology. The specific epithet, alcocki , is given to this species in the presumption that this is the taxon misinterpreted by A. Alcock (1905) to be Paguristes ciliatus of Heller (1862).

Var ia t io n. The chelipeds of the holotype and larger paratypes reasonably can be categorized as unequal, as the size differences between the right and left are substantial. However, the differences seen in the chelipeds of the female and smallest male paratype are less and it is probable that if judged individually, their chelipeds would be described as subequal. The data, based only on five males and one ovigerous female, are too meager for anything other than speculation, but it does seem possible that in P. a l c o c k i n. sp. the degree of cheliped asymmetry is a function of growth.

In contrast, the observed dissimilarities in armature of the right and left chelipeds appear to be specific characters of the species, despite observed intraspecific variation. The dorsomesial margins or marginal areas of the left chela are armed with several (palm) or numerous (dactyl) small spines and/or tubercles; these same margins of the right chela are provided with four to six more prominent spines (palm) and a row of moderately­sized spines (dactyl). Whereas the dorsal surfaces of the dactyls of both chelae have a moderate to dense covering of small tuberculate spines and spinules, the dorsal surface covering of the palm and fixed finger of the left chela consists of scale­like flattened tuberculate protuberances, each often provided with one to three tiny, corneous­tipped spinules. These surfaces on the right chela may have a covering of very small, tuberculate spines that may or may not be corneous­tipped, or, as in the smallest male and female, low, spinulose subrectangular tubercles. The armature of mesial faces of the dactyls is also somewhat dissimilar, albeit variable. The spination of the left dactylar mesial face is masked with short dense setae, but consists of numerous, rather closely­spaced, small tubercles and spinules ( Fig. 1 b), some corneous­tipped or corneous­capped, with a distinctly unarmed area proximally in the ventral half of the surface. This face of the right chela frequently lacks the dense pilosity of the left and is provided with somewhat larger, often corneouscapped tubercles ( Fig. 1 d) arranged in irregular rows over the entire surface. The ambulatory legs also exhibit variations in armature between the second and third pereopods as can be seen in Figures 2 e–h.

Affinities. Among Australian species of Paguristes , P. alcocki n. sp. appears most closely allied to P. kimberleyensis Morgan & Forest, 1991 , sharing with that species the tendency toward dissimilarities in the size and armature of the chelipeds. However, as indicated in the discussion of variation, cheliped inequality appears to be a function of growth in P. alcocki , whereas in P. kimberleyensis the differences between the right and left chelipeds are consistent regardless of animal size or sex. The two species may be distinguished by the armature of the mesial faces of the dactyls of the chelipeds that in P. alcocki consists of a covering of small spines or spinules in irregular rows, but in P. kimberleyensis of one or two longitudinal rows of small spines. Additionally, but subject to more variation, the ocular peduncles of P. alcocki are longer and slenderer; the armature of the dorsal surface of the left cheliped consists of more flattened, scale­like tubercles, and the external lobe of the male first gonopod is better developed.

Although only faint coloration remained in the holotype of P. kimberleyensis (cf. Morgan & Forest 1991), reexamination of the holotype by the first author however showed that the color in preservative of the chelipeds and ambulatory legs was mottled orange and white and that of the dactyls of second and third pereopods each had a band of white at the base of the claw. In contrast, the mesial and lateral faces of the meri of the chelipeds of P. alcocki ( Fig. 3 ) each has an ovate patch of red (in life) or orange (in preservative) most prominent on the mesial face; the segments of the ambulatory legs have median broad bands of red or reddish orange.

Paguristes alcocki n. sp. also appears closely allied to P. balanophilus Alcock, 1905 . As with Alcock’s P.? ciliatus, Indian specimens of P. balanophilus have not been available for examination; however, Morgan and Forest (1991), reporting on specimens of that species in the collections of the Muséum national dHistoire naturelle, described P. balanophilus as having chelipeds, although dissimilar in size, similar in form and spination. Although Alcock (1905) commented that with the exception that the inner margin of the right carpus was spinose, the chelipeds were similar in sculpture, his illustration ( Alcock 1905 , pl. 3: fig. 1) does not show any notable difference between the right and left carpi. As previously indicated, the dissimilarity in size between the right and left chelipeds appears to be growth related in P. a l c o c k i, but the dissimilarity in armament in the new species is not. This character alone should distinguish P. alcocki from P. balanophilus . One differentiating character cited by Alcock was the bi­ or trifid ocular acicles of P. balanophilus and the acuminate (or simple) ocular acicles of the species he interpreted as P.? ciliatus . The ocular acicles are simple in the holotype and paratypes of P. alcocki ; nevertheless, variability cannot be discounted. McLaughlin (unpublished) noted that the ocular acicles of P. kimberleyensis varied from being armed with a single spine to having up to three.

Remarks. Wang (1983) provided a brief description of a species he identified as Paguristes ciliatus of Heller (1862), but his description was based on Alcock’s (1905) interpretation of the species. However, Alcock provided no illustration of the species he had questionably assigned to Heller’s (1862) taxon. Wangs (1982, pl. 1: fig. 2) illustration is of a specimen lacking the posterior portion of the abdomen and there is considerable similarity between Wang’s illustration and Heller’s (1865, pl. 7: fig. 6) rather stylized drawing of a hermit crab partially withdrawn into its shell, including the equal and similar chelipeds and stout ocular peduncles. It is quite clear that Wang (1983) did not illustrate a specimen of P. alcocki n. sp. or P. lewinsohni n. sp., but it cannot be said with certainty what species that author actually had.

In their comparison of P. runyanae Haig & Ball, 1988 , with other Indian Ocean and Japanese species of Paguristes, Haig & Ball’s (1988) remarks regarding the armature of the chelipeds of P. balanophilus and P. c i l i a t u s were taken from Alcock’s (1905) descriptions. Similarly, the distributional records of P. ciliatus in Chinese waters by Wang (1992, 1994) and Rahayu (2000) did not involve examined specimens.

Figures

FIGURE 1. Paguristes alcocki n. sp., Western Australia: a, f, holotype male (7.8 mm) (WAM C 29554); b – d, male paratype (7.5 mm) (WAM C 16493) e, ovig. female paratype (5.5 mm) (WAM C 16751). a, shield and cephalic appendages (aesthetascs and most setae omitted); b, left first pleopod (external view); c, left first pleopod (internal view); d, left second pleopod (external view); e, left first pleopod (external view); f, telson (setae omitted). Scales equal 1 mm.

FIGURE 2. Paguristes alcocki n. sp., Western Australia: holotype male (7.8 mm) (WAM C 29554). a, chela and carpus of left cheliped (dorsal view; setae omitted); b, dactyl of left chela (mesial view, setae omitted); c, chela and carpus of right cheliped (setae omitted); d, dactyl of right chela (mesial view, most setae omitted); e, right second pereopod (lateral view, setae omitted); f, dactyl and propodus of left second pereopod (mesial view, setae omitted); g, left third pereopod (lateral view); h, dactyl and propodus of right third pereopod (mesial view). Scales equal 2 mm.

FIGURE 3. Paguristes alcocki n. sp., Philippine Islands, Panglao Expedition, stn L 43: male (8.6 mm) (NMP). Photo by Chia­Wei Lin.