Paguropsis andersoni (Alcock, 1899), resurrected

Lemaitre, Rafael, Rahayu, Dwi Listyo & Komai, Tomoyuki, 2018, A revision of " blanket-hermit crabs " of the genus Paguropsis Henderson, 1888, with the description of a new genus and five new species (Crustacea, Anomura, Diogenidae), ZooKeys 752, pp. 17-97 : 36-44

Paguropsis andersoni (Alcock, 1899), resurrected Figs 1E, 2C, D, 5C, D, 8C, 9, 10, 14B, 28B, Table 1

Chlaenopagurus Andersoni Alcock, 1899: 115, pl. 1 (type locality: Indian Marine Survey Investigator, off Comorin).

Chlaenopagurus andersoni Alcock & McArdle, 1901: pl. 53, figs 1, 1a, 2, pl. 54, figs 1, 1a; Alcock, 1901: 229; Alcock, 1902: 67, fig. 2.

Paguropsis typica : Alcock, 1905: 28, pl. 2; Balss, 1924: 775, figs 30, 32 (see “Remarks” under P. typica ); Balss, 1927: 963, fig. 1059; Thompson, 1943: 414 (see “Remarks”); Balss, 1956: 1429 (in part); Barnard, 1962: 240; Russell, 1962: 19, fig. 12; Sarojini and Nagabhushanam, 1972: 250, fig. I, fig. A, B, C; Kensley, 1981: 33 (list); Thomas, 1989: 59; Schäfer et al., 1983: figs 12 (in part, see “Remarks” under P. typica ); Emmerson, 2016: 449 (list).

Paguropsis typicus : Thompson, 1943: 413 (see “Remarks”); Kamalaveni, 1950: 77, fig. 1 (see “Remarks”); Gordan, 1956: 325 (in part, see “Remarks” under P. typica ).

P. tyica (misspelling): Schäfer et al., 1983, fig. 12 (in part, see “Remarks”)

Type material.

Lectotype herein selected: off Cape Comorin (Kanyakumari), Laccadive Sea, Indian Ocean, HM Indian Marine Survey Steamer Investigator, [probably sta 258, see “Remarks”], 23 Apr 1899, 08°23'N, 76°28'E, 186.5 m (102 fm): male 18.3 mm (USNM 42719, ex Indian Museum reg. no. 3173-5). Paralectotypes, [same sta data as lectotype]: 2 males 11.7, 17.6 mm (USNM 1441996, ex Indian Museum reg. no. 3173-5); 2 males 7.8, 8.2 mm ( ZMUC-CRU– 006727); 1 ovig female 8.1 mm (BMNH 1899.11.30.3).

Other material.

Philippines: NW coast of Panglao Island, 146.3-548.6 m, [no day] Jan-Mar 2011, coll. J Arbasto: 4 males 14.2-16.3 mm (LKCNHM ZRC 2011.0067). PANGLAO 2004: Balicasag Island, sta PN 1, 09°31'N, 123°41'E, 50-500 m, Apr-Jul 2004, from local fisherman: 1 male 16.6 mm (LKCNHM ZRC 2018.0171).

Indonesia: KARUBAR, RVBaruna Jaya 1: off Tanimbar Island (Arafura Sea), staCP 46, 08°01'S, 132°51'E, 271-273 m, 29 Oct 1991: 7 males 9.3-16.1 mm (USNM 1442005).

Indian Ocean: southwestern India: off Neendakara, Munambam, Kerala State, 30 m, 2006, commercial trawler, coll. A Biju Kumar: 4 males 14.1-18.2 mm (CBM-ZC 10006). Kenya: off Mombasa, RVUjizi, 03°09'S, 40°29'E, [no depth], 24 Mar 1980, coll. WJ Scheffers: 1 male 19.9 mm (RMNH.CRUS.D.34951). Seychelles Islands: CEPROS, traps, Radiale 2, Ech. 34, 04°22.5'S, 56°19.1'E, 200-190 m, 21-22 Oct 1987, coll. A Intes: 1 male 17.3 mm (MNHN-IU-2014-9400). Madagascar: CREVETTIERE 1971, N Madagascar, [Mozambique Channel], sta CH 11, 12°40'S, 48°15'E, 375-385 m, 14 Apr 1971: 2 males 12.4, 20.6 mm, 1 female 17.2 mm (MNHN-IU-2014-9394, = MNHN-Pg 1865); CREVETTIERE 1972, sta CH 32, 12°34'S, 48°18'E, 310-320 m, 13 Sep 1972: 2 males 17.1, 19.6 mm (MNHN-IU-2014-9393, = MNHN-Pg 1864). Mozambique Channel: Mozambique: RVAlgoa, Mozambique Scad Survey SFRI, sta C00815 –014–012– 2144, 23°07.98'S, 35°42.00'E, 180 m, trawl, 12 Dec 1994: 1 male 16.8 mm (SAMC MB-A041691); MAINBAZA, NOVizconde de Eza: Inhambane transect, staCC 3159, 23°55'S, 35°37'E, 148-152 m, 15 Apr 2009, colls. P Bouchet, J Rosado & E Strong: not examined, color photograph (Fig. 8C) (MNHN). KwaZulu-Natal, South Africa: sta NAD11H, 29°46.02'S, 31°16.98'E, 110-130 m, 23 Apr 1958, coll. University of Cape Town Ecological Survey: 1 male 15.0 mm [det. KH Barnard] (SAMC MB-A019489); off Durban, KwaZulu-Natal, Oceanographic Research Institute ORI 68, sta ACEP 1-4, 29°58.56'S, 31°04.98'E, 119 m, trawl, 18 Feb 2010: 1 ovig female 14.4 mm (ZRC 2013.0535); off Durban, KwaZulu-Natal, Oceanographic Research Institute ORI 17, sta ACEP 4-1, 29°06.60'S, 32°07.32'E, 128 m, trawl, 20 Feb 2010: 1 male 14.2 mm (ZRC 2013.0537); Aliwal outer reef, off KwaZulu-Natal, DST/NRF ACEP, RY Angra Pequena, sta R50, 30°12.36'S, 30°59.16'E, 106-149 m, 5 Jun 2017, ROV: specimen not collected, color photograph in situ (Fig. 28B); Coffee Bay (Eastern Cape), 31°59.34'S, 29°09.96'E, 100 m, dredge, 10 Sep 2016: 1 male 24.1 mm (SAMC MB-A066723).

[Locality uncertain]: INVMAR: sta 17, 155-165 m, 3 Aug 1964, coll. OT Chan: 1 ovig female 11.2 mm (MNHN-IU-2014-9412, = MNHN-Pg 1828).

Redescription.

Shield (Figs 2C, 8C, 9A) subtriangular, ca. 1.3 times as long as broad; dorsal surface distinctly rounded, somewhat vaulted, glabrous except for tufts of setae anterolaterally and transverse fringe of short setae on sloping anterior margins of gastric region; anterior margin between rostrum and lateral projections concave; lateral projections broadly triangular, each terminating in small spine; posterior margin roundly truncate; lateroventral distal angle with strong blunt spine near proximal margin of first antennal segment. Rostrum (Fig. 9A) bluntly or sharply triangular, dorsally arched, strongly produced, extending beyond distal margin of ocular acicles, fringed by short marginal setae; with distinct rounded dorsal longitudinal ridge having row of short setae laterally, ending smoothly or in 1 minute subterminal spine. Branchiostegites (Fig. 2D) unarmed except for 1-3 spines on dorsodistal angle, distal margin setose; anterodorsal plate calcified, narrow.

Ocular peduncles ca. 0.4 length of shield, constricted medially and noticeably broadened distally, glabrous except for scattered short dorsodistal setae; corneas strongly dilated, diameter 0.5-0.6 total peduncular length (including the cornea). Ocular acicles small, triangular, each armed with distal or dorsodistal spine often directed anterodorsally.

Antennular peduncles when fully extended overreaching distal margins of corneas by 0.2 length of penultimate peduncular segments. Ultimate and penultimate segments glabrous or at most with scattered short setae. Basal segment with ventromesial tuft of setae distally; lateral face with distal subrectangular lobe, small medial spine, and setose lobe proximally.

Antennal peduncles overreaching distal corneal margins by ca. 0.5 length of fifth segment. Fifth and fourth segments unarmed except for scattered short setae and laterodistal tuft of long setae. Third segment with spine at ventrodistal angle. Second segment with dorsolateral distal angle produced, terminating in small simple or less frequently, bifid spine; mesial margin rounded, setose, and small spine on dorsomesial angle. First segment unarmed except for moderately long setae on lateral face. Antennal acicle length variable with growth, reaching from distal margin of optic calathus to slightly exceeding distal margin of cornea, slender, terminating in sharp spine, with long setae distally, at most with 1 or 2 minute proximal tubercles on mesial margin. Antennal flagellum long, reaching to distal end of cheliped fingers, articles with 1 or 2 short setae (<1 article in length) and usually with 1 or 2 long setae every 12 articles or so.

Mouthparts not markedly different from those described for Paguropsis typica (e.g., Fig. 4 A–F). Maxilliped 3 with exopod ca. 4.2 times as long as broad.

Chelipeds (Figs 1E, 2C, 5C, 8C) subequal, similar in armature and setation; dorsal surfaces of chelae and carpi densely covered with tufts of long, bristle-like setae obscuring spination below, often with areas of short dense plumose setae on dorsal faces of dactyl, fixed finger, and palm; ventral surfaces of palms smooth except for 2 submedian longitudinal rows of well-spaced low tubercles each with tuft of long bristle-like setae. Dactyl and fixed finger with narrow hiatus proximally, forming spoon-like shape in ventral view when closed; each finger terminating in small curved corneous claw and subdistal blunt calcareous tooth ventral to claw, both claws and teeth interlocking when fingers closed; cutting edge of dactyl with terminal row of small, fused corneous teeth on distal one-third, and row of unequal calcareous teeth on proximal two-thirds; cutting edge of fixed finger with row of blunt calcareous teeth decreasing in size distally. Dactyl ca. 1.4 times as long as palm; dorsal surface somewhat convex, armed with small spines proximally and patch of dense, short plumose setae proximally and extending to mesial face; dorsomesial margin rounded; ventral face with well-spaced tufts of long bristle-like setae, lacking spines. Fixed finger with dorsal, lateral, and ven tral surfaces similar to dactyl in armature. Palm ca. 0.6 times as long as carpus, dorsal surface covered with numerous small spines arranged in irregular longitudinal rows and accompanied by tufts of long, setae, strength and number of spines increasing with growth; dorsomesial margin with 2 or 3 rows of strong, well-spaced spines and tufts of long setae; dorsolateral margin rounded, not delimited, with irregular rows of small tubercles or spines, each accompanied by tuft of long setae. Carpus ca. 0.6 times length of merus; dorsal and dorsolateral surfaces with well-spaced spines often bifid or trifid and accompanied by tufts of long bristle-like setae; dorsomesial margin with row of strong spines accompanied by tufts of bristle-like setae, and dorsodistal spine; dorsolateral margin rounded; mesial surface with short transverse rows of bristle-like setae, otherwise smooth; ventral surface smooth except for fringe of long setae on ventrodistal margin extending onto mesial surface. Merus nearly as long as chela, subtriangular in cross-section; dorsal margin with row of protuberances accompanied by tufts of long setae, ventromesial and ventrolateral margins each with irregular row of strong spines with tufts of long setae; lateral and mesial surfaces with tufts of long and short setae. Ischium with row of small spines on ventrolateral margin. Basis with ventromesial row of long setae.

Pereopods 2 and 3 (Fig. 10 A–D) similar in armature and setation, distinctly dissimilar in length, with pereopod 2 shorter than pereopod 3. Dactyls ca. 1.5 (pereopod 2) or 2.2 (pereopod 3) times as long as propodi; with dorsal and ventral margins, lateral and mesial surfaces, with numerous tufts of long, bristle-like setae; dactyl of pereopod 2 weakly curved, lateral surface convex, ventromesial distal margin armed with 10-19 minute corneous spinules; dactyl of pereopod 3 relatively broad on proximal one-third, becoming slender distally, terminating in sharp corneous claw, 1.5-1.6 times as long as dactyl of pereopod 2, lateral and mesial surfaces with shallow but distinct concavity (often weakly calcified) on proximal one-third, ventral margin lacking spines or spinules. Propodi ca. 1.2 times as long as carpi; dorsal and ventral surfaces with tufts of long setae. Carpi unarmed except for tufts of setae dorsally and distolateral fringe of long setae. Meri unarmed except for fringe of long setae ventrally and ventrolaterally (pereopod 2) or ventrally (pereopod 3). Ischia armed with row of small spines and setae (pereopod 2) or unarmed except for row of setae (pereopod 3). Coxae with ventromesial row of setae; coxae of pereopods 3 narrowly separated by ca. 0.2 ventral length of 1 coxa. Sternite XI (of pereopods 3; Fig. 5D) having anterior lobe flat to slightly concave, glabrous or with scattered short setae distally; posterior lobes strongly compressed laterally, each with transverse fringe of setae.

Pereopod 4 (Fig. 10E, F) with chela short, 1.1 times as long as carpus and 2.5 times as long as high. Dactyl and fixed finger leaving wide gap when closed, each terminating in sharp, inwardly curved corneous claw crossing at tips when closed. Dactyl curved inwardly, dorsal margin with row of setae; cutting edge of dactyl with ventrolateral distal row of 6-8 small corneous-tipped spines (in addition to corneous claw). Fixed finger curving inward, cutting edge with 4 or 5 strong corneous-tipped spines (in addition to corneous claw) arranged like bear claw; lateral face usually with 1-4 minute scale-like corneous spines basally. Palm straight or slightly curved, 1.6-1.8 times as long as high; with dense fringe of long setae on dorsal margin, and tufts of setae on ventral margin continued on fixed finger; carpus unarmed except for fringe of long setae dorsally and scarce setae ventrally; merus long, ca. 0.6 times as long as meri of pereopods 2 and 3. Sternite XII broad, with dense fringe of long dense setae (Fig. 5D).

Pereopod 5 (Fig. 10G) with chela ca. 0.6 times as long as merus, with long, brush-like setae on dorsomesial and ventromesial surfaces; merus and carpus each with dorsal and ventral row of long setae. Dactyl with rasp on ventral face. Propodal rasp consist ing of minute, ovate scales, occupying 0.2 length of propodus. Ischium with setae dorsally and ventrally. Coxa with fringe of long bristle-like setae on rounded ventromesial distal angle.

Male gonopod 1 (Fig. 9C) with inferior lamella armed on distal margin with posterior row of slender, semitransparent hook-like spines, and up to 4 or 5 anterior irregular rows of small, straight or slightly curved corneous spines. Gonopod 2 with distal segment strongly twisted distally, densely setose; usually with unpaired, biramous or uniramous, reduced pleopods 3-5 on left side or less frequently on right side; often lacking pleopods 4 or 5 or lacking altogether pleopods 3-5 (see “Variations”).

Female usually with pleopods 2-5 on left side or less frequently on right side, as follows: pleopods 2-4 biramous, well developed, and reduced biramous or uniramous and vestigial pleopod 5 (see “Variations”). Brood pouch large, subquadrate, distal margin scalloped and fringed with setae.

Uropodal exopods (Fig. 9B) slender, broadly curved, terminating in strong spine, anterior margin with fringe of long setae and row of well-spaced corneous-tipped spines; endopods short, strongly curved, anterior margin with long setae and 1 or 2 irregular rows of corneous-tipped spines; protopods with strong, curved proximal spine.

Telson (Fig. 9B) subrectangular, wider than long; posterior lobes separated by shallow median cleft, terminal margins unarmed except for fringe of long setae.

Genetic data.

See Table 1.

Color

(Fig. 8C, 28B). Shield and calcified dorsal portions of posterior carapace orange. Ocular peduncles orange dorsally, white otherwise; corneas black. Ocular acicles light orange. Antennular peduncles and flagella light orange. Antennal peduncles light orange, with color fading to cream or whitish proximally on first to fourth segments. Chelipeds red or orange with white spines and tubercles and yellow bristle-like setae; chelae orange; carpi red; meri dorsal margin red extending to lateral and mesial faces subdistally, dorsodistal margin and most of lateral and mesial surfaces light orange. Pereopods 2 and 3 as follows: dactyl red with white dorsal margin; propodi red with white dorsal margin and scattered small white spots ventrolaterally; carpi red with large white portions on lateral face medially and distally; meri mostly white with reddish dorsal and ventral margins and on lateral face distally; ischium reddish. Pereopods 4 and 5 red or orange.

In explaining the etymology of his genus name Chlaenopagurus where this species was originally placed, Alcock (1899) mentioned that the purple coloration of the polyps that he interpreted to be a colonial zoanthid used by this species, was similar to the chlaina (Gr.), a mantle used in Homeric times for protection against the weather.

Distribution.

Western Pacific: from Philippines and Indonesia (Arafura Sea). Indian Ocean: from Gulf of Martaban, Andaman Sea ( Alcock 1905); India, including eastern ( Sarojini and Nagabhushanam 1972) and western ( Thomas 1989) coasts; Seychelles Islands; eastern Africa, off Kenya; off Madagascar on Mozambique Channel; and eastern coast of South Africa. Depth: 30 to 548.6 m.

Habitat and symbiont.

Found with indeterminate species of acontiate anemone (see “Remarks” under genus).

Variations.

The following morphological features increase with size: length of antennal acicle; density and strength of spines on chelipeds; and density of tufts of setae on chelipeds and ambulatory legs. Larger males have more numerous subdistal spines or rows of spines on the distal margin of gonopod 1 (Fig. 9C).

Of the four females examined, one has pleopods 2-5 on the left side, and the other on the right side; both have pleopod 5 reduced. Of the 29 males examined, 53.8% had one or more unpaired pleopods 3-5 on the left side, 15.4% on the right side, 7.7% did not have any unpaired pleopods on either side, and 23.1% had paired pleopods 3-5. As in males of P. typica , the male pleopods 3-5 are reduced, uni- or biramous.

Affinities.

As previously mentioned under the “Remarks” of Paguropsis typica , P. andersoni can be distinguished primarily from that species and other congenerics by the distinct longitudinal concavity present on the lateroproximal surface of the dactyls of pereopods 3 (second ambulatory legs). In addition, the coxae of pereopods 3 (Fig. 5D) are noticeably more narrowly separated (by ca. 0.2 ventral length of 1 coxa) from each other than in other congeners, and the posterior lobes of sternite XI are noticeably compressed. Other characters setting P. andersoni apart, albeit subject to some variability related to size, include the more numerous and stronger spination of the chelipeds, particularly on the dorsal surface of carpus, chela, ventromesial and ventrolateral margins of merus; the dense tufts of setae on chelipeds and meri to dactyls of ambulatory legs; and pereopod 4 with a shorter chela relative to the carpus length.

Coloration is clearly distinct in Paguropsis andersoni when compared to other congeners as well as with all other species discussed herein (see Figs 8, 18, 28). The overall color of P. andersoni (Figs 8C, 28B) does bear some general similarity with that of P. typica (Figs 8A, B, 28A); however, the ocular peduncles, chelae, and ambulatory legs in each of these two species have a different pattern. In P. andersoni the ocular peduncles are light orange dorsally, and white otherwise (vs. light orange overall with a darker orange band in P. typica ), the chelae are mostly orange (vs. mostly whitish in P. typica ), and the propodus and dactyl of pereopods 2 and 3 are mostly solid red except for white dorsal margins of dactyls (vs. reddish mottled with white spots, and a median longitudinal white line on the lateral surface of the propodus, in P. typica ).

Remarks.

Alcock (1905) concluded, without providing any explanation, that his genus and species described earlier as Chlaenopagurus andersoni Alcock, 1899, were the same as Henderson’s (1888) genus and species Paguropsis typica , and thus placed his name in the synonymy of the latter. Alcock’s synonymy has stood since that time. However, detailed study of types and specimens deposited in various museums, as well as recently collected material of Paguropsis , has shown that Alcock’s name actually represents a valid and morphologically distinct species, and as such is resurrected herein with a lectotype selected from the syntype series. Alcock (1905: 30) described the coloration of P. typica and its cnidarian symbiont, as follows "The colour of the crab is red: the coenosarc of the polyp-colony is bluish, the polyps themselves are dark purple", actually is applicable as well to P. andersoni .

When Alcock (1899) described Chlaenopagurus andersoni he did not designate a holotype among his numerous specimens, and thus all are syntypes, several of which were distributed to major museums such as the USNM, BMNH, and ZMUC. A lectotype is herein selected for Alcock’s taxon from the syntypes exchanged with the USNM. The labels with the syntype specimens sent to USNM lacked a station number, but based on all other information accompanying these syntypes and comparing them with Alcock’s (1902) detailed station data, it seems clear that they came from Investigator Survey station 258.

Several studies have reported new specimens collected since Henderson’s (1888) description, as Paguropsis typica . These are as follows: Alcock (1905), from the Gulf of Martaban (Andaman Sea); Balss (1927), from the "Indian Ocean"; Thompson (1943, spelled both P. typicus and P. typica ), from Zanzibar; Barnard (1962), from East Africa (Natal); and Sarojini and Nagabhushanam (1972), from Waltair (eastern India, Bay of Bengal). Based on information therein, and in light of the finding during this study that Henderson’s (1888) P. typica has not been found outside the western Pacific, these reports are herein referred to P. andersoni . The lists or catalogues of hermit crabs from southern Africa by Kensley (1981) and Emmerson (2016) that have included P. typica in the fauna from that region have been based on Barnard’s (1962) original male specimen (SAMC MB-A019489) which is shown here to actually be P. andersoni .

As mentioned under the “Remarks” for Paguropsis typica , a number of reports ( Balss 1924, 1956, Gordan 1956) that have used that name actually represent, in part, P. andersoni , as does the distribution map used by Schäfer et al. (1983).

In a summary of the hermit crabs from the Indian Museum, Kamalaveni (1950) based his discussion of Paguropsis typica (spelled P. typicus ) exclusively on the material used by Alcock (1899) in his description of Chlaenopagurus andersoni , a taxon shown here to be a valid species of Paguropsis . Thus, Kamalaveni’s report pertains entirely to P. andersoni .