Paguropsina inermis 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 : 72-79

Paguropsina inermis gen. et sp. n. Figs 18D, 25, 26, 27, Table 1

Type material.

Holotype: male 3.7 mm, New Caledonia, NORFOLK 2, Antigonia Bank, staCP 2119, 23°23'S, 168°02'E, 300 m, 1 Nov 2003 (MNHN-IU-2014-9386).

Paratypes.

Japan: Ogasawara Islands: TRVShin’yo-maru 1997 research cruise, sta 17: off Chichi-jima Island, 27°24.58'N, 142°10.21'E, 210-212 m, 16 Oct 1997, coll. T Komai: 1 ovig female 2.9 mm (CBM-ZC 14204). RVKoyo, 2009 research cruise, sta 21: NW of Otouto-jima Island, 27°13.09'N, 142°09.19'E, 136 m, 15 Jul 2009, coll. T Komai: 1 ovig female 3.8 mm (CBM-ZC 14205); sta 28, E of Nishi-jima Island, 27°07.05'N, 142°10.68'E, 52 m, 15 Jul 2009, coll. T Komai: 1 female 2.5 mm, color photograph (Fig. 18D) (CBM-ZC 14206); sta 34, W of Minami-jima Island, 27°02.34'N, 142°07.52'E, 139-140 m, coll. T Komai: 1 female 2.6 mm (CBM-ZC 14207).

South China Sea: ZHONGSHA 2015, ORI cruise 1113: staCP 4160, 20°48.88'N, 116°43.153'E, 251 m, 30 Jul 2015: 1 ovig female 4.5 mm (NTOU A01447).

Philippines: MUSORSTOM 1, NOVauban: N Lubang, sta CP63, 14°00'N, 120°16'E, 191-195 m, 27 Mar 1976: 1 female 6.1 mm (MNHN-IU-2014-9372). PANGLAO 2004: W of Pamilacan Island, Cervera shoal, sand on echinoderms bed, sta T37, 09°28'N, 123°51'E, 134-190 m, 4 Jul 2004: 1 ovig female 4.2 mm (LKCNHM ZRC 2018.0172). PANGLAO 2005, NO “DA-BFAR”: Bohol Sea, off Balicasag Island, staDW 2402, 09°31'N, 123°42'E, 101-118 m, rock/sand/corals, 31 May 2005: 3 males 2.7-3.9 mm (LKCNHM ZRC 2018.0173).

Indonesia: KARUBAR, NOBaruna Jaya 1: Kai Islands, sta DW18, 05°18'S, 133°01'E, 205-212 m, 24 Oct 1991: 2 males 3.1, 3.2 mm, 1 female 3.5 mm (MNHN-IU-2014-9380).

Fiji Islands: BORDAU 1, NOAlis: Lau Ridge, Yangasa Cluster, sta DW1497, 18°44'S, 178°25'W, 335-350 m, 12 Mar 1999: 1 male 2.5 mm, 1 female 3.0 mm (MNHN-IU-2013-19456).

Tonga Islands: BORDAU 2, NOAlis: Vava’u group, sta DW1583, 18°37'S, 174°03'W, 327-360 m, 13 Jun 2000: 1 female 3.0 mm (MNHN-IU-2013-19457).

New Caledonia: BATHUS 3, NOAlis: Norfolk Ridge, W of Mont Jumeau, staCP 805, 23°41'S, 168°01'E, 278-310 m, 27 Nov 1993: 1 male 3.4 mm (MNHN-IU-2014-9378). LITHIST, NOAlis: Norfolk Ridge, W of Jumeau Bank, staCP 17, 23°41'S, 168°01'E, 247-281 m, 12 Aug 1999: 1 male 5.7 mm (MNHN-IU-2014-9379). NORFOLK 1, NOAlis: Norfolk Ridge, Brachiopode Bank, staDW 1651, 23°26'S, 167°50'E, 276-350 m, 19 Jun 2001: 4 males 3.1-4.6 mm (MNHN-IU-2014-9352), 2 females 2.8, 3.6 mm (MNHN-IU-2014-9362); Norfolk Ridge, Brachiopode Bank, staDW 1652, 23°27'S, 167°51'E, 290-378 m, 19 Jun 2001: 1 male 4.6 mm (MNHN-IU-2014-9353); Norfolk Ridge, Brachiopode Bank, sta DW1653, 23°26'S, 167°51'E, 328-340 m, 19 Jun 2001: 4 males 3.6-4.8 mm, 1 female 3.7 mm (MNHN-IU-2014-9355), 1 male 4.2 mm, 1 3.6 mm (MNHN-IU-2014-9381); Norfolk Ridge, Brachiopode Bank, staDW 1657, 23°26'S, 167°50'E, 305-332 m, 19 Jun 2001: 1 female 4.8 mm (USNM 1441977); Norfolk Ridge, Brachiopode Bank, staDW 1658, 23°27'S, 167°50'E, 320-336 m, 19 Jun 200: 1 female 3.4 mm (MNHN-IU-2013-19455); Norfolk Ridge, W of Jumeau Bank, staCP 1669, 23°41'S, 168°01'E, 302-325 m, 21 Jun 2001: 1 male 4.3 mm, 1 female 3.9 mm (MNHN-IU-2014-9351); Norfolk Ridge, W of Jumeau Bank, sta CP1671, 23°42'S, 168°01'E, 320-397 m, 21 Jun 2001: 1 male 5.1 mm (MNHN-IU-2014-9359); Norfolk Ridge, Kaimon-Maru Bank, staCP 1682, 24°42'S, 168°09'E, 331-379 m, 22 Jun 2001: 1 male 4.5 mm (MNHN-IU-2014-9357); Norfolk Ridge, Kaimon-Maru Bank, sta CP1683, 24°44'S, 168°07'E, 248-272 m, 22 Jun 2001: 1 male 4.5 mm (USNM 1441892); Norfolk Ridge, Crypthelia Bank, staDW 1724, 23°19'S, 168°15'E, 200-291 m, 27 Jun 2001: 1 female 3.0 mm (MNHN-IU-2014-9358). NORFOLK 2, NOAlis: Brachiopode Bank, staDW 2023, 23°27'S, 167°51'E, 282-297 m, 21 Oct 2003: 1 male 4.3 mm (MNHN-IU-2014-9388); Brachiopode Bank, staDW 2024, 23°28'S, 167°51'E, 370-371 m, 21 Oct 2003: 1 ovig female 4.5 mm (MNHN-IU-2014-9383); Kaimon-Maru Bank, staCP 2094, 24°44'S, 168°10'E, 286-300 m, 29 Oct 2003: 1 ovig female 3.9 mm (MNHN-IU-2014-9382), 1 male 4.3 mm (MNHN-IU-2014-9385); Antigonia Bank, staCP 2119, 23°23'S, 168°02'E, 300 m, 1 Nov 2003: 2 ovig females 3.7, 3.8 mm (USNM 1441978); Crypthelia Bank, staDW 2124, 23°18'S, 168°15'E, 260-270 m, 2 Nov 2003: 1 ovig female 3.6 mm (MNHN-IU-2014-9390).

Description.

Shield (Figs 18D, 25A) subovate, about as long as broad; dorsal surface glabrous except for 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 (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, glabrous dorsomedian longitudinal ridge. Lateral projections each terminating in short vertical keel-like ridge with 2 or 3 small blunt spines distally. Gastric region weakly elevated anteriorly. Branchiostegite (Fig. 25B) with anterodorsal plate unarmed except for 1-3 small blunt distal spines, and setose distal margin.

Ocular peduncles strongly broadened distally, ca. 0.5 length of shield; corneas strongly dilated, diameter ca. 0.7 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 margin of corneas. Fifth segment slender, glabrous or with scattered setae. Fourth segment with few 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. 25A) 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 setae 1 to 2 flagellar articles in length.

Mouthparts similar to those described for the type species Paguropsis pistillata sp. n. Maxilliped 3 (Fig. 27A) with exopod 2.7 times as long as broad.

Chelipeds (Figs 18D, 25C, D) 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, strong calcareous teeth on proximal two-thirds; cutting edge of fixed finger with row of blunt, irregular calcareous teeth on proximal two-thirds, and row of partially fused, subequal, small calcareous teeth on distal third. Dactyl as long as palm; dorsal surface convex, weakly pitted and mostly unarmed except for scattered low tubercles with 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 except for well-spaced tufts of short to moderately long setae; 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 few long setae on distal margin. Merus slightly shorter to nearly as long as chela, sub triangular 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, and row of small spines on ventromesial margin. Basis with ventromesial row of setae. Coxa with well-marked longitudinal fissure (Fig. 27B) on ventral surface.

Pereopods 2 and 3 (Fig. 26 A–D) similar in armature and setation, slightly dissimilar in length, with pereopod 2 shorter than pereopod 3. Dactyls ca. 1.5 (pereopod 2) or 1.8 (pereopod 3) times as long as propodi, mostly straight in lateral view except for weak distal curvature, terminating in sharp corneous claw; dorsal margins each with moderately dense, long simple setae; ventral margins each variably armed, with row of short or obscure spines, or with row of long, slender corneous spines; dorsomesial margins and mesial faces each usually with several tufts or short transverse rows of long, slender corneous spines (more numerous on pereopod 3); dactyl of pereopod 3 slender, ca. 1.2 times as long as dactyl of second pereopod. Propodi ca. 1.1 times as long as carpi; dorsal margin with few 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 with small blunt spine or obscure small tubercle. Meri unarmed except for few long setae dorsally and fringe of long setae ventrally. Ischia unarmed except for scattered short setae. Coxae of pereopods 3 (Fig. 27B) widely separated by ventral length of 1 coxa, with few ventromesial setae. Sternite XI (between pereopods 3; Fig. 27B) with undivided anterior lobe consisting of narrow rod-like plate 8-10 times as broad as long.

Pereopod 4 (Fig. 27C, D) with chela club-like, ca. 1.3 times as long as carpus and ca. 2.5 times as long as high; palm ca. 1.7 times 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; dorsal margin with scattered setae distally; cutting edge unarmed. Fixed finger broad basally, slightly bulging at base, glabrous, terminating in sharp corneous claw; cutting edge unarmed. Palm smooth, unarmed except for few setae on dorsal margin and distolateral margin next to base of dactyl. Sternite XII (between pereopods 4; Fig. 27B) with transverse fringe of setae all across.

Pereopod 5 (Fig. 27E) with chela 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 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, corneous spines. Gonopod 2 with distal segment strongly twisted distally, densely setose. Left unpaired pleopods 3-5 reduced when present (see Variations); when present, pleopod 3 biramous, pleopods 4 and 5 uniramous; no pleopods 3-5 on right side.

Female with left unpaired, well-developed, biramous pleopods 2-4 (ovigerous), rarely with vestigial pleopod 5; usually without 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. 25F) 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. 25F) subrectangular, slightly broader than long; posterior lobes usually broadly rounded, separated by shallow median cleft, terminal margins unarmed except for fringe of long setae.

Genetic data.

See Table 1.

Color

(Fig. 18D). Shield overall light orange overall, with darker orange and pair of white spots marking anterior margin of gastric region. Ocular acicles white. Ocular peduncles whitish basally, light orange distally, and with dark orange portion distolaterally and on optic calathus; corneas black except for somewhat yellowish external membrane. Antennular and antennal peduncles white to light orange. Chelipeds with meri, carpi, and chelae orange with irregular pattern and shapes of small white spots, and white spines; dactyls each with red spot basally; carpi each with red spot distodorsally; meri each with small red spots, one on dorsal margin distally, and three on distal margin. Pereopods 2 and 3 light to dark orange or reddish mixed with irregularly shaped white areas; dactyls white on distal one-third; carpi and meri each white distally and with small red spot distolaterally. Pereopod 4 with dactyl light orange dorsally, white distally and along cutting edge; palm and fixed finger mostly white except for orange medially on ventral and dorsal margins; carpus white to light orange, with darker orange on dorsal margin; merus distally light orange with darker orange on ventral margin, and white ventroproximally. Pereopod 5 mostly white with some light orange around margins of segments.

Etymology.

The species name derives from the Latin inermis, meaning unarmed, and refers to the lack of armature on the cutting edge and lateral face of the fixed finger of pereopod 4, the main characteristic setting of this species.

Distribution.

Western Pacific: Japan (Ogasawara Islands), South China Sea, Philippines, Indonesia (Banda Sea), Fiji Islands, Tonga Islands, and New Caledonia. Depth: 101 to 397 m.

Habitat and symbiont.

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

Variations.

As noted above, the armature of the dactyls of pereopods 2 and 3 is noticeably variable among the numerous specimens examined of this new species. The dorsomesial and ventromesial margins vary in armature from having bristle-like setae and obscure or altogether lacking any clearly visible corneous spines (e.g., in the holotype, Fig. 26B, D) to the margins armed with long, slender, corneous spines. When corneous spines are present, they can be arranged in dorsomesial and ventromesial rows of single spines (pereopod 2), or in rows of 1-3 clustered spines (pereopod 3). The presence or strength of the armature of the dactyls do not appear to be related to size of the specimens.

In the 25 males examined, the presence of left unpaired pleopods 3-5 is variable, as follows: 77% have reduced, biramous left pleopod 3; 55% have a reduced, uniramous pleopod 4; and 11% have a reduced, uniramous pleopod 5; 22% lack pleopods 3-5 altogether; no male specimens were found to have pleopods 3-5 on right side. Virtually all 22 females examined had pleopods 2-4 only on the left side and lacked pleopod 5. However, 10% of the females had a uniramous, vestigial pleopod 5. Only one ovigerous female (3.8 mm, CBM-ZC 14205) from Ogasawara Islands, Japan, was found to have right unpaired pleopods 2-4.

Remarks.

See Paguropsina pistillata gen. et sp. n.