Paguropsina pistillata gen. et

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 : 66-72

Paguropsina pistillata gen. et sp. n. Figs 18C, 21D, E, 23, 24, Table 1

Type material.

Holotype: 1 male 4.4 mm, New Caledonia, EBISCO, NOAlis, staCP 2499, Capel Bank, 24°53'0"S, 159°52'0"E, 286-529 m, 7 Oct 2005 (USNM 1442008).

Paratypes.

Philippines: PANGLAO 2004, W Pamilacan I. Cervera shoal, sta T37, 09°28'N, 123°51'E, 134-190 m, 4 Jul 2004: ovig female 4.2 mm, color photograph (Fig. 18C) (LKCNHM ZRC).

Indonesia: Danish Kei Islands Expedition: sta 49, 05°37'10"S, 132°24'E, 245 m, 3 May 1922: 1 ovig female 4.4 mm ( ZMUC-CRU– 007046).

Salomon Islands: SALOMON 1, NOAlis: N Malaita, staDW 1778, 08°19'S, 160°34'E, 157-253 m, 29 Sep 2001: 1 male 2.7 mm (MNHN-IU-2014-9368); NW San Cristobal, staCP 1831, 10°12'S, 161°19'E, 135-325 m, 5 Oct 2001: 1 male 4.0 mm, 1 ovig female 3.1 mm (ex MNHN-IU-2013-5582, USNM 1441980); E of Guadalcanal, staCP 1857, 09°40'S, 160°49'E, 720-849 m, 7 Oct 2001: 1 female 3.4 mm (MNHN-IU-2014-9369).

New Caledonia: MUSORSTOM 6, NOAlis: Loyalty Islands, [sta number lost]: 1 male 3.1 mm (USNM 1441979). LIFOU, NOAlis: Lifou, Santal Bay, SE of Récif Shelter, staDW 1648, 20°54'S, 167°03'E, 150-200 m, 7/19 Nov 2000: 2 ovig females 3.1, 3.4 mm (MNHN-IU-20149375). NORFOLK 1, NOAlis: Norfolk Ridge, Brachiopode Bank, staDW 1657, 23°26'S, 167°50'E, 305-332 m, 19 Jun 2001: 1 female 3.7 mm (MNHN-IU-2014-9363); Norfolk Ridge, Kaimon-Maru Bank, staDW 1679, 24°45'S, 168°10'E, 298-324 m, 22 Jun 2001: 1 female 4.0 mm (MNHN-IU-2014-9354). EBISCO, NOAlis: Capel Bank, staCP 2492, 24°44'S, 159°41'E, 285 m, 6 Oct 2005: 74 males 1.8-2.3 mm, 65 females 1.9-3.4 mm, 23 ovig females 3.0-4.0 mm (MNHN-IU-2014-9401); Capel Bank, staCP 2493, 24°44'0"S, 159°43'0"E, 285-545 m, 6 Oct 2005: 1 male 4.1 mm (USNM 1442021), 56 males 2.5-4.3 mm, 15 females 1.9-3.7 mm, 48 ovig females 1.9-3.4 mm (MNHN-IU-2014-9402); Capel Bank, staCP 2499, 24°53'S, 159°52'E, 286-529 m, 07 Oct 2005: 2 males 2.4, 3.3 mm (MNHN-IU-2013-5659); Capel Bank, staCP 2505, 24°45'S, 159°43'E, 328-463 m, 7 Oct 2005: 1 male 4.0 mm, 1 ovig female 3.6 mm (MNHN-IU-2014-9391); Capel Bank, staCP 2507, 24°43'0"S, 159°43'0"E, 286 m, 7 Oct 2005: 1 male 4. 0 mm (USNM 1442011); Capel Bank, staDW 2508, 24°41'0"S, 159°43'0"E, 304-350 m, 7 Oct 2005: 1 male, 3.2 mm (USNM 1442012); Kelso Bank, staDW 2513 24°6'0"S, 159°42'0"E, 280-500 m, 8 Oct 2005: 1 female 3.0 mm (USNM 1442025); Kelso Bank, staCP 2519, 24°8'0"S, 159°42'0"E, 310 -463 m, 8 Oct 2005: 2 males 3.0, 3.1 mm (USNM 1442023); Nova Sud Bank, staCP 2524, 24°6'0"S, 159°42'0"E, 315-325 m, 9 Oct 2005: 1 ovig female 3.0 mm (USNM 1441985); N of Nova Bank, staDW 2538, 22°20'S, 159°25'E, 318-323 m, 10 Oct 2005: 1 ovig female 3.3 mm (MNHN-IU-2014-9392); Chesterfield Plateau, staCP 2591, 19°4'0"S, 158°28'0"E, 244-258 m. 17 Oct 2005: 1 female ovig 3.7 mm (USNM 1442010); Chesterfield Plateau, staCP 2592, 19°42'0"S, 158°30'0"E, 273-281 m, 17 Oct 2005: 1 male 4.1 mm (USNM 1442024); Chesterfield Plateau, staCP 2593, 19°43'0"S, 158°32'0"E, 300-323 m, 17 Oct 2005: 1 male 6.0 mm (USNM 1442022).

Chesterfield Islands, Coral Sea: MUSORSTOM 5, NOCoriolis: Lord Howe Ridge, Capel Bank, staCP 269, 24°47'S, 159°37'E, 250-270 m, 9 Oct 1986: 4 males 2.5-3.3 mm, 1 ovig female 3.1 mm (MNHN-IU-2014-9409); Lord Howe Ridge, Capel Bank, staDW 260, 25°29'S, 159°44'E, 285 m, 8 Oct 1986: 1 male 3.6 mm (MNHN-IU-2014-9407); Lord Howe Ridge, Capel Bank, staDW 274, 24°45'S, 159°41'E, 285 m, 9 Oct 1986: 1 female 2.2 mm (MNHN-IU-2014-9408); Lord Howe Ridge, Capel Bank, staCP 275, 24°46.60'S, 150°40.30'E, 285 m, 9 Oct 1986: 1 male 3.7 mm (USNM 1441989); Lord Howe Ridge, Argo Bank, sta DC 291, 23°07.70'S, 159°28.40'E, 300 m, 11 Oct 1986:1 male 3.9 mm (USNM 1442009); Lord Howe Ridge, Nova Bank, staCP 312, 22°17'S, 159°25'E, 315-320 m, 12 Oct 1986: 1 male 2.8 mm (MNHN-IU-2014-9406).

Description.

Shield (Figs 18C, 23A) 0.9 to 1.1 longer than broad; dorsal surface glabrous or with scattered setae on sloping lateral surfaces; anterior margins between rostrum and lateral projections concave; posterior margin broadly rounded; lateroventral distal angle produced into small blunt spine-like projection (often with 2 minute terminal tubercles) adjacent to proximal margin of first antennal segment. Rostrum roundly subtriangular, relatively broad, weakly arched and curved ventrally, reaching to distal margin of ocular acicles; with rounded and glabrous dorsal longitudinal ridge. Lateral projections each terminating in short vertical keel-like ridge with 2 or 3 small blunt spines. Gastric region weakly elevated anteriorly. Branchiostegite (Fig. 23B) with anterodorsal plate unarmed or with small blunt distal spine; distal margin setose.

Ocular peduncles strongly broadened distally, ca. 0.5 length of shield; corneas strongly dilated, diameter ca. 0.8 of total peduncular length (including the cornea). Ocular acicles small, obtusely triangular, armed with minute subterminal blunt spine directed anterodorsally.

Antennular peduncles when fully extended overreaching distal margins of corneas by entire or nearly entire length of ultimate peduncular segments. Ultimate and penultimate segments glabrous or at most with scattered short setae. Basal segment with lateral face having distal subrectangular lobe, minute medial spine, and setose lobe proximally.

Antennal peduncles reaching nearly to distal corneal margins. Fifth segment slender, glabrous or with scattered setae. Fourth segment with scattered setae. Third segment with short ventrodistal spine. Second segment with dorsolateral distal angle not noticeably produced, terminating in short spine; mesial margin rounded, setose, dorsomesial distal angle blunt, unarmed. First segment (Fig. 23A) hardly visible in dorsal view or hidden by shield, unarmed. Antennal acicle short, only reaching to distal margin of fourth peduncular segment or mid-point of ocular peduncle, unarmed, terminating bluntly and with few short distal setae. Antennal flagellum short, delicate, not exceeding distal margin of chelae, with few short setae and 1 or 2 long setae every 4-6 flagellar articles.

Mouthparts. Mandible with stout palp. Maxillule with recurved external lobe of endopod nearly as long as entire endopod. Maxilla with endopod not exceeding distal end of scaphognathite. Maxilliped 1 with endopod bent medially nearly at right angle, reaching distal end of exopod; epipod elongated. Maxilliped 2 without distinguishing characters. Maxilliped 3 (Fig. 23C) with exopod ca. 2.4 times as long as broad; merus with 3-5 small spines on ventral margin, and usually 2 small spines on ventromesial distal angle; ischium having crista dentata armed with 15-18 small subequal (except for larger distal and proximal) corneous-tipped teeth; basis with row of small spines on mesial margin; coxa with ventromesial angle strongly produced ventrally, with 2-4 small spines and fringe of setae. Sternite VIII narrow, with small setose lobe on each side of midline.

Chelipeds (Figs 18C, 23D, E) subequal, similar in armament and setation; dorsal surfaces of chelae and carpi with weakly dense short setation mostly arranged in tufts; ventral surfaces of palms smooth except for scattered setae or tufts of setae. Dactyl and fixed finger with narrow hiatus proximally when closed, forming spoon-like shape in ventral view when closed; each 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 as long as palm; dorsal surface convex, weakly pitted and mostly unarmed except for short setae; mesial margin rounded, with few small tubercles; ventromesial face concave. Palm as long as carpus, dorsal surface with scattered small tubercles on dorsolateral and dorsomesial margins, mostly unarmed medially, usually with dense patch of short plumose setae medially near base of fixed finger; dorsolateral margin rounded, not delimited, dorsomesial margin with row of strong spines. Carpus ca. 0.6 times length of merus; dorsal and dorsolateral surfaces with scattered small spines or tubercles; dorsomesial margin with row of weak to moderately strong spines or tubercles, and small blunt distal spine; dorsolateral margin rounded; mesial surface smooth, unarmed except for setae on distal margin; ventral surface smooth except for row of setae on distal margin. Merus nearly as long as chela, subtriangular in cross-section; dorsal margin with row of low protuberances accompanied by tufts of short setae, ventromesial and ventrolateral margins each with irregular row of weak spines or tubercles with setae; lateral and mesial surfaces unarmed except for scattered short setae. Ischium with lateral surface rounded, unarmed, ventromesial margin with row of small spines. Basis with ventromesial row of setae. Coxa with well-marked longitudinal fissure (Fig. 23F) on ventral surface.

Pereopods 2 and 3 (Fig. 24 A–D) slender, similar in armature and setation, slightly dissimilar in length, with pereopod 2 shorter than pereopod 3. Dactyls ca. 1.4 (pereo pod 2) or 1.7 (pereopod 3) times as long as propodi, mostly straight in lateral view except for weak distal curvature, terminating in sharp corneous claw; dorsal and ventral margins each with moderately dense simple setae or tufts of setae (some on dorsal margin occasionally bristle-like); ventromesial margins each with 2 or 3 obscure, minute corneous spinules distally; dactyl of pereopod 3 slender, nearly straight in lateral view, 1.1 times as long as dactyl of second pereopod. Propodi ca. 1.2 times as long as carpi; dorsal margin mostly with tufts of long setae, ventral margin with long simple setae or tufts of setae, lateral and mesial faces with scattered short setae. Carpi unarmed except for tufts of setae dorsally and scattered setae ventrally, dorsodistal angle blunt or with obscure small tubercle. Meri unarmed except for fringe of long setae ventrally. Ischia unarmed except for scattered short setae. Coxae of pereopods 3 (Fig. 21D) widely separated by full ventral length of 1 coxa, with few ventromesial setae. Sternite XI (between pereopods 3; Fig. 21D) with undivided anterior lobe consisting of narrow rod-like plate 8 times as broad as long; posterior lobes wider than long, glabrous.

Pereopod 4 (Figs 21E, 24E, F) with chela club-like, almost 1.1 times as long as carpus and 2.4-3.1 as long as high; palm 1.7-2.2 as long as high. Dactyl strongly curved, hook-like, crossing fixed finger at tip when fingers closed, terminating in distal or subdistal sharp corneous claw; cutting edge unarmed or rarely with few minutely obscure corneous spinules. Fixed finger broad, bulging ventrally at base, glabrous, terminating in sharp corneous claw; cutting edge with 1 distinct sharp corneous-tipped spine (often slightly offset laterally from cutting edge). Palm and carpus with long simple setae or tufts of setae on dorsal margins. Sternite XII (between pereopods 4; Fig. 21D) with fringe of setae more dense laterally than medially.

Pereopod 5 (Fig. 24G) with chela nearly 0.7 times as long as merus, with long, brush-like setae on dorsal and ventral surfaces. Dactyl with propodal rasp on ventral face. Propodal rasp consisting of minute ovate scales extending for ca. 0.1 length of propodus. Ischium with setae dorsally and ventrally. Coxa with ventrodistal setae.

Male gonopod 1 with inferior lamella armed on distal margin with posterior row of slender, semitransparent hook-like spines, and 1 or 2 irregular rows of small straight or slightly curved corneous spines. Gonopod 2 with distal segment strongly twisted distally, densely setose. Left unpaired pleopods 3-5 reduced when present, pleopod 3 biramous, pleopods 4 and 5 uniramous; no pleopods 3-5 on right side (see “Variations”).

Female with left unpaired, well-developed, biramous pleopods 2-4 (ovigerous), rarely with vestigial pleopod 5; lacking or rarely having unpaired pleopods 2-5 on right side (see “Variations”). Brood pouch large, oblong, distal margin weakly scalloped and fringed with sparse short setae.

Uropodal exopods (Fig. 23G) slender, broadly curved, terminating in strong, usually corneous-tipped spine, anterior margin with fringe of long well-spaced setae and row of well- spaced corneous-tipped spines; endopods relatively short, curved, anterior margin with long setae and 1 or 2 irregular rows of corneous-tipped spines; protopods with strong, curved proximal spine.

Telson (Fig. 23G) subrectangular, broader 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. 18C). Shield light orange-red except for white anterior margins. Ocular acicles light orange with white-tipped distal spine and small reddish spot mesially. Antennular and antennal peduncles light orange fading to transparent on distal segments. Ocular peduncles light orange proximally, whitish distally except for orange-red median portion of optic calathus; with dark orange-red band medially; corneas black except for somewhat yellowish external membrane. Chelipeds with carpus and chela with mostly light orange to red background, and white spines or tubercles; dactyl white except for light red portion medially, and small orange spot basally; fixed finger white except for small orange spot mesially at base of larger teeth of cutting edge, and orange portion basally, white coloration continued posteriorly on most of lateral face of palm; carpus with small white portion basally and distally; merus orange mottled with white, with small dorsodistal, laterodistal and mesiodistal dark orange or reddish spot. Pereopods 2 and 3 with dactyls semi-transparent except for median and basal red bands; carpi and meri mottled with semi-transparent white and light orange-red spots or blotches; meri with light orange background and mottled with white and red spots. Pereopod 4 light with dactyl light orange with white tip; chela mostly white except for light orange dorsal margin; carpus mostly white with light orange distal, ventral and proximal margins; merus white with light orange band medially. Pereopod 5 light orange.

Etymology.

The species name derives from the Latin pistillum, a club-shaped pounder used in a mortar, and refers to the characteristic shape of the chela of pereopod 4.

Distribution.

Western Pacific: from the Philippines, Indonesia (Arafura Sea), Solomon Islands, and New Caledonia. Depth: 135 to 849 m.

Habitat and symbiont.

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

Variations.

Of the 152 males examined, 133 (87.5%) have unpaired pleopods 3-5 (reduced, uni- or biramous) on the left side, and the remaining lack unpaired pleopods on either side. Of the 166 females examined, 99% have unpaired pleopods 3-5 on the left side.

Remarks.

This new species and Paguropsina inermis gen. et sp. n. are very similar. However, the two can be immediately separated by the difference in armature of the cutting edge of the fixed finger on the chela of pereopod 4. In P. pistillata gen. et sp. n. the cutting edge is armed with one distinct, sharp corneous-tipped spine that is often slightly offset laterally from the cutting edge, whereas the cutting edge in P. inermis gen. et sp. n. is unarmed. Coloration also differs in these two congeners (Fig. 18C, D), primarily on the pattern of the chelipeds (pereopod 1) and pereopods 2 and 3. The chela is orange to red with white spines, and the fixed finger and distolateral half of the palm are white in P. pistillata gen. et sp. n., whereas the chela is orange with irregular pattern and shapes of small white spots and white spines in P. inermis gen. et sp. n. Pereopods 2 and 3 have dactyls that are semi-transparent except for median and basal red bands, and the propodi, carpi and meri are mottled with semi-transparent white and light orange-red spots or blotches in P. pistillata gen. et sp. n., whereas pereopods 2 and 3 are light to dark orange or reddish mixed with irregularly-shaped white areas, the dactyls are white distally and proximally, and red medially, and propodi, carpi and meri are white distally with a small red spot distolaterally in P. inermis gen. et sp. n.