Oncopagurus monstrosus ( Alcock, 1894 (Alcock, 1894)

Lemaitre, R., 1996, Hermit crabs of the family Parapaguridae (Crustacea: Decapoda: Anomura) from Australia: species of Strobopagurus Lemaitre, 1989, Sympagurus Smith, 1883 and two new genera., Records of the Australian Museum 48 (2), pp. 163-221 : 199-201

Oncopagurus monstrosus ( Alcock, 1894 )

Figs 19, 20

"? Parapagurus monstrosus" Alcock, 1894: 243 (type locality, by lectotype designation: Bay of Bengal).

Sympagurus monstrosus .- Henderson, 1896: 533.- Alcock & Anderson, 1897, pI. 32, fig. 4.- Alcock, 1901: 223.­ Lemaitre, 1989: 37.- Lemaitre, 1994: 412.

Sympagurus arcuatus var. monstrosus .- Alcock, 1905: 104, pI. 10, fig. 5.- Gordan, 1956: 341.- Kemp & Sewell, 1912: 26.

? Eupagurus brevimanus .-Yokoya, 1933: 90, fig. 34. (See remarks)

Parapagurus monstrosus .- Miyake, 1978: 72 (key); 1982: 119, pI. 40, fig. I.- Baba et al., 1986: 302, fig. 146.­ Imafuku, 1992: 234, unnumbered fig.

not Parapagurus arcuatus var. monstrosus .- Balss, 1912: 99, pI. 10, fig. 3. (= Sympagurus brevipes [De Saint Laurent, 1972]).

Type material. LECTOTYPE (herein selected): male (SL 4.2 mm), Indian Ocean, Bay of Bengal, [probably from HM Indian Marine Survey Steamer Investigator , sta. 120, 15°56'50"N, 81°30'30"E, 439 m, 24 Dec 1890], USNM 156566. PARALECTOTYPES: 2 males (SL 3.4, 3.7 mm), same sta. data as lectotype, USNM 156566.

Australian material. WESTERN AUSTRALIA: 15 males (SL 3.6 -5.1 mm), 2 females (SL 3.9, 4.6 mm), 3 females ovig. (SL 4.2-4.8 mm), NW of Augustus Is., FRV Soeia, sta. 011 84/079, 13°17'S, 122°37.4'E, 494- 484 m, 15 Feb 1984, WAM 1321-86. 1 male (SL 5.0 mm), NW of Augustus Is., FRV Soeia, sta. 01184/078, 13°27.6'S, 122°44.4'E, 444- 440 m, coil. S. Slack-Smith, WAM 1238 -86. 4 males (SL 4.9- 5.2 mm), NW of Collier Bay, FRV Soeia, sta. 01184/070, 13°44'S, 122°13.3'E, 496- 494 m, 13 Feb 1984, coli. S. Slack-Smith, WAM. 1 male (SL 5.2 mm), NW of Cape Leveque, FRV Soeia, sta. SO1184/063, 14°43.1'S, 121°33.1'E, 410- 408 m, 12 Feb 1984, WAM 1090-86. 20 males (SL 3.7- 5.3 mm), NW of Beagle Bay, FRV Soeia, sta. 01/84/060, 15°08.6'S, 121°03.4'E, 500-504 m, 11 Feb 1984, coil. S. Slack-Smith, WAM 1079-86, 1084-86. 2 males (SL 5.5, 6.0 mm), NW of Beagle Bay, FRV Soeia, sta. 01184/058, 15°12.8'S, 121°05.9'E, 410- 404 m, 11 Feb 1984, coli. S. Slack-Smith, WAM 1078-86, 1134-86. 2 males (SL 5.7, 6.0 mm), North West Shelf, FRV Soeia, sta. NWS-7, 18°33.2'S, 117°30.9'E, 392-400 m, 25 Apr 1983, NTM Cr 010913. 1 male (SL 6.6 mm), 1 female (SL 5.8 mm), North West Shelf, FRV Soeia, CSIRO cruise 0184, sta. 22, 18°34.4'S, 117°30'E, 202 m, 1 Feb 1984, NTM Cr 000665, 000667. 2 males (SL 4.5, 5.2 mm), North West Shelf, FRV Soeia, sta. 0184/16, 18°37.4'S, 117"02.4'E, 504-508 m, 31 Jan 1984, NTM Cr 011546.

Other material (all from Albatross). PHILIPPINES: 2 males (SL 4.2, 4.5 mm), sta. 5268, Verde Is., 13°42'N, 120057'15"E, 311 m, 8 Jun 1908, USNM 168923. 1 female ovig. (SL 3.7 mm), sta. 5123, Mindoro Is., 13°12'45"N, 121°38'45"E, 518 m, 2 Feb 1908, USNM 168920. 1 female ovig. (SL 3.4 mm), sta. 5124, Mindoro Is., 12°52'N, 121°48'20"E, 514 m, 2 Feb 1908, USNM 168921. 2 males (SL 3.7, 4.5 mm), sta. 5214, Masbate Is., 12°25'18"N, 123°37'15"E, 399 m, 21 Apr 1908, USNM 168922. 2 males (3.3, 4.3 mm), 3 females (SL 2.5- 2.8 mm), I female ovig. (SL 2.8 mm), sta. 5402, between Leyte and Cebu, 11°11'45"N, 124°15'45"E, 344 m, 16 Mar 1909, USNM 168924, 168925. 2 males (SL 3.1-3.2 mm), sta. 5404, Leyte, Dupon Bay, 10050'N, 124°26'18"E, 347 m, 17 Mar 1909, USNM 168927. 1 male (SL 5.2 mm), sta. 5405, Leyte, Dupon Bay, 10049'20"N, 124°24'23"E, 479 m, 17 Mar 1909, USNM 168928. I male (SL 2.4 mm), sta. 5535, between Cebu and Siquijor Is., 09°20'30"N, 123°23'45"E, 567 m, 19 Aug 1909, USNM 168935. 1 male (SL 4.8 mm), sta. 5541, N of Mindanao, 08°49'38"N, 123°34'30"E, 401 m, 20 Aug 1909, USNM 168936. I male (SL 5.1 mm), sta. 5517, N of Mindanao, 08°45'30"N, 123°33'45"E, 309 m, 9 Aug 1909, USNM 168934. 6 males (SL 3.1-4.8 mm), sta. 5506, N of Mindanao, 08°40'N, 124°31'45"E, 479 m, 5 Aug 1909, USNM 168932. 3 males (SL 3.9- 5.1 mm), 1 female (SL 5.2 mm), sta. 5501, N of Mindanao, 08°37'37"N, 124°35'E, 391 m, 4 Aug 1909, USNM 168929. 1 male (SL 4.5 mm), 2 sex indet. (SL 3.6, 5.1 mm), sta. 5502, N of Mindanao, 08°37'37"N, 124°35'E, 391 m, 4 Aug 1909, USNM 168930. 4 females (SL 3.7 -5.2 mm), sta. 5504, N ofMindanao, 08°35'30"N, 124°36'E, 366 m, 5 Aug 1909, USNM 168931. 1 male (SL 4.3 mm), 3 females (SL 3.7-4.9 mm), sta. 5508, N of Mindanao, Iligan Bay, 08°17'24"N, 124°l1'42"E, 494 m, 5 Aug 1909, USNM 168933. I male (SL 3.4 mm), sta. 5550, Sulu Sea, 1010 Is., 06°02'N, 120044'40"E, 472 m, 17 Sep 1909, USNM 168937. I female (SL 4.3 mm), sta. 5551, Sulu Sea, Jolo Is., 05°54'48"N, 120044'24"E, 353 m, 17 Sep 1909, USNM 168938.

INDONESIA: 4 males (SL 3.6-4.0 mm), 1 female (SL 3.3 mm), 1 female ovig. (SL 3.4 mm), sta. 5590, Borneo, Sibuko Bay, off Mabul Is., 04°1O'50"N, 118°39'35"E, 567 m, 29 Sep 1909, USNM 168939. 1 male (SL 4.2 mm), 1 female (SL 2.7 mm), sta. 5622, Moluccas, offMakyan Is., 00019'20"N, 127°28'30"E, 503 m, 29 Nov 1909, USNM 168940. 1 male (SL 4.8 mm), 1 female (SL 2.8 mm), 00012'15"N, 127°29'30"E, 527 m, 29 Nov 1909, USNM 168941.

Diagnosis. Shield ( Fig. 19a ) as long as broad; dorsal surface weakly calcified medially; rostrum broadly rounded, with low dorsal ridge; anterior margins weakly concave; lateral projections broadly subtriangular, usually terminating in small spine; ventrolateral margin unarmed or occasionally with small spine; posterior margin broadly rounded. Ocular peduncles more than half length of shield; ocular acicles subtriangular, terminating in strong spine; corneae dilated. Sternite of 3rd maxillipeds with small spine on each side of midline. Antennular peduncle exceeding distal margin of corneae by full length of ultimate segment. Antennal peduncle ( Fig. 20a ) exceeding distal margin of cornea by at most 0.25 length of 5th segment; 3rd segment with strong ventromesial distal spine; 2nd segment with dorsolateral distal angle produced, terminating in strong spine; acicles at most slightly exceeding distal margin of corneae, mesial margin armed with 8 to 15 spines; flagellum with series of short setae « 1 article in length) and long setae (> 3 articles in length) every 8 to 20 articles. Chelipeds markedly dissimilar, with some iridescence and moderately dense setae. Right cheliped ( Figs 19 c-e, 20 b-d) with chela less than twice as long as broad (males), or about as long as broad (females); fingers curved ventromesially; dactyl with concave ventromesial face; palm with irregular rows of small spines medially on dorsal face, and dorsolateral and dorsomesial margins well delimited by row of spines; mesial face of palm rounded, with small spines or tubercles. Left cheliped ( Fig. 19b ) with palm and carpus often weakly calcified; carpus with dorsodistal spine. Ambulatory legs ( Fig. 19 f-h) with ventromesial row of about 5 (occasionally up to 15) small corneous spines on dactyl, and dorsal and dorsomesial rows of long setae; carpus with small dorsodistal spine; merus of right 3rd pereopod unarmed, (rarely 1 or 2 small dorsal spines). Anterior lobe of sternite of 3rd pereopods with small marginal spine, setose. Fourth pereopod ( Fig. 19i ) with dactyl terminating in short, corneous claw; propodal rasp consisting of ovate scales. Vropods and telson ( Fig. 19j ) markedly asymmetrical. Telson lacking transverse suture separating anterior and posterior lobes; posterior lobes separated by V-shaped median cleft, terminal margins armed with often strongly curved corneous spines. Male 1st gonopods ( Fig. 20e ) each with weakly concave distal lobe; 2nd gonopods ( Fig. 20t ) each with distal segment nearly flat. Females with vestigial right 2nd pleopod.

Colour. [Based on Miyake (1982: 118, pI. 40, fig. 1), Baba et al. (1986: 146, pI. 302), and Imafuku (1992: 234)]. Carapace light orange. Left cheliped, and 2nd and 3rd pereopods, light pink with two orange-red spots on mesial and lateral faces of meri, carpi, and propodi (spots on meri often partially fused). Right cheliped with chela, distal two-thirds of carpus, and distal third of merus, cream white; merus and carpus with orange-red portion proximally

Habitat and symbiotic associations. Found in gastropod shells usually with actinian attached to shell.

Distribution. Indo Pacific: Gulf of Aden; Bay ofBengal; Japan; Philippines; Indonesia; and Australia. Depth: 202 to 1000 m.

Affinities. As previously mentioned, Oncopagurus monstrosus is similar to 0. indicus , and often the two are difficult to separate. Individuals of 0. monstrosus grow to a larger size than 0. indicus . The most reliable characters in distinguishing between the two include size, development of ocular peduncles and corneae, and armature of the merus of the right 3rd pereopod (see "Affinities" under 0. indicus ).

Remarks. Because of the potential for confusion of this species with 0. indicus , a lectotype is herein selected for 0. monstrosus .

De Saint Laurent (1972) questionably synonymised Eupagurus brevimanus Yokoya, 1933 , with Parapagurus monstrosus Alcock, 1894 . From Yokoya's brief description it is not possible to confirm whether his taxon is indeed a synonym of Oncopagurus monstrosus , and his specimens are probably no longer extant.

Figures

Fig. 19. Oncopagurus monstrosus (Alcock, 1894). a, shield and cephalic appendages; b, carpus and chela of left cheliped; c, carpus and chela of right cheliped; d, chela of same, lateral; e, same, mesial; f, right 2nd pereopod, lateral, g, dactyl of same, mesial; h, right 3rd pereopod, lateral; i, propodus and dactyl of left 4th pereopod; j, telson. Scales = 1 mm (a), 2 mm (b-e), 1 mm (f-h), 0.5 mm (i,j). (lectotype male [SL 4.2 mm], Bay of Bengal, USNM 156566).

Fig. 20. Oncopagurus monstrosus (Alcock, 1894). a, right antennal peduncle, lateral; b, right cheliped of female; c, right chela of male, ventral; d, right chela of male, ventral; e, male right 1st gonopod, mesial; f, male right 2nd gonopod, posterior. Scales 1 mm (a); 2 mm (b-d), 0.5 mm (e,f). (a,e,f, lectotype male [SL 4.2 mm], Bay of Bengal, USNM 156566; b, female [SL 3.4 mm], Indonesia, USNM 168939; c, male [SL 4.2 mm], Indonesia, USNM 168940; d, male [SL 5.1 mm], Philippines, USNM 168931).