Troglocarcinus corallicola Verrill, 1908

TAVARES, MARCOS & MENDONÇA, JOEL BRAGA DE JR., 2022, Brachyuran crabs (Crustacea, Decapoda) from the remote oceanic Archipelago Trindade and Martin Vaz, South Atlantic Ocean, Zootaxa 5146 (1), pp. 1-129 : 81-86

Troglocarcinus corallicola Verrill, 1908

( Figs. 44C, F, G , 45A–F )

Troglocarcinus corallicola Verrill, 1908: 427 [Type locality: Bermuda].

Troglocarcinus hirsutus Canário, Badaró, Johnsson & Neves, 2015: 78 [Type locality: 13°07’S, 38°45’W, Caramuanas Reef, Itaparica Island, Salvador, Bahia].

Trindade and Martin Vaz specimens. 1 male, 1 female juveniles ( MZUSP 40381 ), Brazil, off Espírito Santo, Trindade Island, Ponta da Calheta , 20°30’18.7’’S, 29°18’31.6’’W, J.B. Mendonça coll., 24.x.2014, 15.4 m . 1 ovigerous female ( MZUSP 40378 ), ibidem, 29.iv.2014, 15.9 m . 1 male ( MZUSP 40390 ), ibidem, 16.xi.2017, 17.1 m . 1 male ( MZUSP 41579 ), ibidem, 9.vii.2015, 16.3 m . 1 ovigerous female ( MZUSP 40209 ) , 1 male ( MZUSP 40211 ) , 1 female ( MZUSP 40216 ), ibidem, Enseada dos Portugueses , SECOM/ECIT, 20°30’20.9’’S, 29°18’43.7”W, J.B. Mendonça coll., 9.viii.2018, 16.1 m , associated with Mussismilia . 1 ovigerous female ( MZUSP 40213 ), ibidem, 26.vii.2018, 11.5 m . 1 male ( MZUSP 40210 ) , 1 male ( MZUSP 40220 ), 1 ovigerous female ( MZUSP 40218 ), ibidem, 20°30’29.9’’S, 29°18’43.7”W, J.B. Mendonça coll., 26.vii.2018, 16.5 m . 2 females ( MZUSP 39594 ), ibidem, Ponta Norte , 20°29’40.2’’S, 29°20’32.9”W, J.B. Mendonça coll., 1.iv.2014, 11.5 m , associated with Mussismilia . 1 female carrying a few zoeas ( MZUSP 39592 ), Enseada da Cachoeira , 20°30’57.1’’S, 29°20’15.2”W, J.B. Mendonça coll., 9.vii.2012, 13.8 m . 1 male ( MZUSP 40389 ), 1 ovigerous female ( MZUSP 40217 ), ibidem, Farrilhões , 20°31’29.8’’S, 29°19’52.0”W, J.B. Mendonça coll., 6.viii.2018, 10.4 m . 1 male, 1 female ( MZUSP 39593 ), ibidem, 20°31’22.4’’S, 29°19’52.0”W, J.B. Mendonça coll., 5.v.2014, 14.4 m , associated with Mussismilia . 1 male ( MZUSP 40215 ), ibidem, Enseada das Orelhas , 20°29’40.2’’S, 29°20’32.9”W, J.B. Mendonça coll., 21.xi.2017, 9.6 m . 2 females ( MZUSP 40784 ), ibidem, 6.vii.2013, 14 m , associated with Mussismilia . 4 females, 3 ovigerous ( MZUSP 41581 ), ibidem, 16.v.2014 , associated with Mussismilia . 1 male ( MZUSP 40809 ), ibidem, 16.v.2014, 10.4 m , associated with Mussismilia . 3 males (1 juvenile), 1 ovigerous female ( MZUSP 40776 ), ibidem, 18.iv.2014 , associated with Mussismilia. 1 ovigerous female (MZUSP 40387), ibidem, Parcel das Tartarugas, 20°31’10.4’’S, 29°17’58.4”W, J.B. Mendonça coll., 19.vi.2016, intertidal, 1.0 m. 2 females, 1 ovigerous (MZUSP 40791), ibidem, 20°31’01.3’’S, 29°17’56.9”W, J.B. Mendonça coll., 10.vii.2015, 13.9 m. 1 ovigerous female ( MZUSP 40383 ) associated with Favia , 2 ovigerous females ( MZUSP 40775 ), ibidem, Enseada do Príncipe, Pedra da Garoupa , 20°31’35.5’’S, 29°18’94.0” W, J.B. Mendonça coll., 16.vii.2013, 10.4 m. 3 females (2 ovigerous, 1 juvenile) ( MZUSP 40391 ), 1 ovigerous female ( MZUSP 40608 ), ibidem, between Lixo and Calheta beaches, 20°31’29.8’’S, 29°19’43.9”W, J.B. Mendonça coll., 24.iv.2014, 17.9 m, associated with Mussismilia . 1 male, 1 female ( MZUSP 40785 ), ibidem, 2.vii.2012, 25 m, associated with Mussismilia . 1 male, 5 ovigerous females ( MZUSP 40788 ), ibidem, 15.viii.2013, 17 m, associated with Mussismilia . 1 juvenile female ( MZUSP 40770 ), ibidem, Ilha da Racha, 20°30’26.5’’S, 29°20’48.0”W, J.B. Mendonça coll., 3.vii.2015, 23 m. 1 male, 5 females (3 ovigerous) ( MZUSP 39598 ), ibidem, Ponta Norte, Crista do Galo, 20°29’14.84’’S, 29°20’13.95”W, J.B. Mendonça coll., 21.v.2014, 15 m, associated with Mussismilia . 1 male, 1 female ( MZUSP 40800 ), ibidem, 20°29’22.22’’S, 29°20’2.87”W, J.B. Mendonça coll., 14.ii.2019, 2.5 m, associated with Siderastrea . 1 ovigerous female ( MZUSP 39598 ), ibidem, Ponta Norte, Enseada, 2029’18.7S, 2920’18.3” W, J.B. Mendonça coll., 18.vii.2013, 13.9 m, associated with Mussismilia . 1 male, 1 female, 2 juveniles ( MZUSP 40782 ), Laje Pedra da Naja , 20°29’57.8’’S, 29°20’39.2”W, J.B. Mendonça coll., 13.vii.2015, 19.5 m , associated with Mussismilia . 1 male, 1 juvenile female ( MZUSP 40384 ), ibidem, Laje da Ponta Noroeste , 20°29’57.8’’S, 29°20’39.2’’W, J.B. Mendonça coll., 16.vii.2012, 15.3 m . 2 males, 2 females ( MZUSP 40816 ), ibidem, Praia dos Cabritos , 20°29’41.38’’S, 29°19’39.9’’W, J.B. Mendonça coll., 8.viii.2018, 8.5 m , associated with Siderastrea . 1 badly damaged female ( MZUSP 40681 ), Martin Vaz Archipelago , 20°30’45.7’’S, 29°18’21.9”W, J.B. Mendonça coll., 23.vii.2013, 13 m , associated with Mussismilia . 1 damaged ovigerous female ( MZUSP 40798 ), ibidem, 24.vii.2013, 12.3 m , associated with Mussismilia .

Size of largest male: cl 2.8 mm, cw 2.3 mm; largest female: cl 3.4 mm, cw 2.9 mm.

Comparative material examined. Troglocarcinus corallicola : western Atlantic: Bermuda: 1 ovigerous female, cl 3.0 mm, cw 2.3 mm topotypic ( USNM 231679 ), Castle Island, Castle Harbor , Causeway , Savazzi coll. viii.1982, associated with the scleractinian coral Isophyllia . Florida : 1 female, cl 4.5 mm, cw 3.5 mm ( USNM 61517 ), 23°39’N, 82°51’W, W. Langley coll., viii.1927. Puerto Rico: 1 ovigerous female, cl 4.0 mm, cw 3.0 mm ( USNM 231690 ), SE coast, V. A. Capriles coll., associated with the scleractinian corals Diploria strigosa (Dana) , Isophyllia sinuosa (Ellis & Solander) and Mycetophyllia sp. Brazil: Paraíba: 3 ovigerous females, 1 male ( MZUSP 6083 ), Tambaú , Quebra-Quilha Reef, P. Young coll., 4.i.1983, associated with Mussismilia . 1 male, 13 females (6 ovigerous) ( MZUSP 6084 ), ibidem, P. Young coll., 20.viii.1982, associated with Mussismilia . 3 females ( MZUSP 41578 ), ibidem, associated with Siderastrea . 1 male, 4 females ( MZUSP 6085 ), Tambaú , Picãozinho Reef, P. Young coll., 12.xii.1983. 1 male, 1 female ( MZUSP 41577 ), ibidem, 17.xi.1982, associated with Mussismilia . Bahia: 1 male ( MZUSP 38004 ), 1 ovigerous female ( MZUSP 37888 ), Boipeba Island , Bainema Reef , M Tavares et al. coll., 17–31.i.2015. 1male, 1 ovigerous female ( MZUSP 38893 ), ibidem, 13°39.556’S, 38°153.988’ W, M. Tavares coll., 17–31.i.2015. 1 male, 1 female ( MZUSP 40818 ), 2 males, 1 ovigerous female ( MZUSP 40786 ), ibidem, 13°37.653’S, 38°53.475’W, M. Tavares and J.B. Mendonça coll., 2.iii.2013, associated with Mussismilia . São Paulo: 3 males ( MZUSP 11856 ), 5 ovigerous females ( MZUSP 11857 ), Alcatraz Archipelago, J. Nogueira coll. Central Atlantic : 1 male, 1 ovigerous female ( USNM 231682 ), Ascension Island, Mcarthur Point, M. L. Jones coll., 12.vii.1976, associated with Favia . Eastern Atlantic : Gulf of Guinea: 1 female, cl 3.0 mm, cw 2.5 mm ( USNM 233468 ), São Tomé and Príncipe, S. Tomé Island , S. Gofas coll., xi.1983, associated with Favia gravida . Troglocarcinus hirsutus (junior synonym of T. corallicola ): Brazil: Bahia: 1 female paratype, cl 5.0 mm, cw 3.5 mm ( USNM 1207439 ), Baía de Todos os Santos, Caramuanas Reef, I. Cruz and N. Menezes coll., 14.xii.2010, associated with the scleractinian coral Mussismilia braziliensis . 1 male, cl 3.8 mm, cw 2.5 mm and 1 female 3.9 mm, cw 3.0 mm paratypes ( USNM 1207444 ), ibidem, Caramuanas Reef, 4.ii.2011. 2 females paratypes, cl 4.9 mm, cw 3.5 mm and cl 3.7 mm, cw 2.6 mm ( USNM 1207440 ), ibidem, Boa Viagem Beach, 2.iii.2010, associated with Mussismilia hispida . 1 male, 1 female paratypes ( USNM 1207441 ), 1 female paratype, cl 3.5 mm, cw 2.7 mm ( USNM 1207442 ), 1 male paratype ( USNM 1207443 ) cl 3.2 mm, cw 2.5 mm, Camamu Bay , Morere Reef, 19.ii.2011, associated with Mussismilia braziliensis (Verril) .

Distribution. Amphi-Atlantic. Western Atlantic: Bermuda, Florida, Gulf of Mexico, Antilles, Brazil (Maranhão to São Paulo) ( Utinomi 1944; Coelho 1966; Coelho & Ramos 1972; Melo 1996; Nogueira 2003). The Alcatraz Archipelago (São Paulo) represents the southernmost record of T. corallicola . Brazilian oceanic islands: São Pedro and São Paulo Archipelago ( Kropp & Manning 1987), Rocas Atoll and Fernando de Noronha ( Coelho 1966; Coelho & Ramos 1972). This is the first record of T. corallicola from Trindade and Martin Vaz. Central Atlantic: Ascension and Saint Helena islands ( Kropp & Manning 1987). Eastern Atlantic: Gabon to Gulf of Guinea (São Tomé, Principe, Pagalu) ( Manning & Chace 1990).

Ecological notes. Obligate symbiont of stone corals, T. corallicola ( Fig. 45A–F ) is notorious among the cryptochirid crabs for its low specificity ( Kropp & Manning 1987). Indeed, it has been known to live in association with a wide range of coral hosts, including: astrocoeniids, caryophyliids, faviids, meandrinids, merulinids, montastreids, mussids, oculinids, and siderastreids to depths of 75 m (see Kropp & Manning 1987, and Meij 2014a for the coral host species). The prevalence and density rates of T. corallicola on the coral hosts decrease slightly over increasing depth ( Tienderen & Meij 2016). Apparently, free-living males visit females of the same species lodged in her gall in the coral host ( Meij 2014a). In Trindade, a free-living male was observed on a coral ( Fig. 45E ), and crescenticshaped dwelling openings were common ( Fig. 45F ). The females carried noticeably large eggs ( Fig. 45C, D ) and the female MZUSP 39592 had a number of zoeas in her brood pouch.

Remarks. Canário et al. (2015) described a second species in Troglocarcinus , T. hirsutus , based on many specimens but from only three sampling sites near one another along the coast of Bahia ( Brazil), namely: Boa Viagem Beach, Itaparica and Boipeba islands. Troglocarcinus hirsutus and T. corallicola are acknowledged very close to each other. Canário et al. (2015) advanced four distinguishing characters between T. hirsutus and T. corallicola , none of which can actually be used confidently to distinguish between the two species. The purported distinguishing characters are discussed hereafter (character states for T. corallicola , between brackets, based on Kropp & Manning, 1987, as specimens of T. corallicola s. str. were not examined by Canário et al. 2015):

1) anterior deflection of the carapace at an angle up to almost 70 (vs deflection angle up to 60). However, in Troglocarcinus the carapace deflection angle varies with age and sex. While adult females have the carapace strongly deflected anteriorly at an angle almost up to 90 (see below), developing females have the anterior part of the carapace less deflected (see also Kropp & Manning, 1987: 16). In some adult females (e.g. Ascension Island USNM 231682; Trindade MZUSP 40387, MZUSP 39593; Alcatraz MZUSP 11857; and São Tomé Island in the Gulf og Guinea USNM 233468) the carapace is strongly deflected anteriorly at an angle almost up to 90. Males always have comparatively weakly deflected carapaces anteriorly.

2) “carapace with several large spines delimiting the protogastric and mesogastric regions, especially four large spines in a row along mesogastric swelling towards the front” (vs tubercles instead of spines not arranged in a row on the mesogastric swelling). The carapace ornamentation varies substantially, even between specimens of the same sex, similar in size. Kropp & Manning (1987: fig. 7a, b) illustrated a female of T. corallicola from Tortugas with three large spines arranged in a row delimiting the carapace protogastric and mesogastric regions. Some specimens from the Alcatraz Island (see above under comparative material) are distinctly more spiny than others. Small specimens of T. hirsutus usually have larger spines, such as the females paratypes USNM 120441 and USNM 120442, whereas the female paratype USNM 1207439 is devoid of spines delimiting the carapace protogastric and mesogastric regions.

3) thoracic sternite 4 covered with setae (vs “naked” sternite 4). Kropp & Manning (1987) (identification key and under the definition of Troglocarcinus ) actually referred to “P1-sternite smooth” as opposed to P1-sternite tuberculate. Therefore, they were not referring to the absence of setae on the P1-sternite, although the sternite 4 was illustrated in outline without setae in T. corallicola ( Kropp & Manning, 1987: fig. 7d). The setae on the P1-sternite can be minute and their density and distribution on the sternite are uneven regardless of the sex and size of the specimens. The ovigerous females of T. corallicola MZUSP 39593 from Trindade and USNM 231690 from Puerto Rico, for instance, are provided with many, long setae on the P1-sternite. The use of setae on the P1-sternite in sorting out species in Troglocarcinus is therefore of limited use, if useful at all.

4) third female pleopod uniramous or biramous (vs only uniramous third pleopod). It has been long known that the female cryptochirid has only three pairs of pleopods (pleopods 2, 3 and 4 on the pleonal somites 2, 3 and 4, respectively) ( Utinomi, 1944; Fize & Serère, 1957; Kropp & Manning, 1987). The form of the female second pleopod has been shown to vary considerably from specimen to specimen (biramous, uniramous, knob-like, one side uniramous and biramous on the other side, pleopod poorly developed) in Utinomiella dimorpha and two other Indo-West Pacific species ( McCain & Coles, 1979; Kropp & Manning, 1987; Kropp, 1990), whereas the Pl4 uniramous is a stable character used to define the family Cryptochiridae ( Kropp & Manning 1987: 2) . Both, T. corallicola and T. hirsutus , have the female Pl2 biramous and Pl4 uniramous. However, the females paratypes of T. hirsutus examined here have a uniramous Pl3, just as the females of T. corallicola USNM 231679 topotypic and USNM 231690 from Puerto Rico. It is actually unknown how many females were reported by Canário et al. (2015) to have the third pleopod uniramous and how many had pleopods biramous among the specimens examined by Canário et al. (2015). Also, it is of great interest to know in the females examined by Canário et al. (2015) if the third pleopod can be one side uniramous and biramous on the other side. A meaningful number of specimens from northern localities should be examined in order to ascertain whether the third pleopod uniramous and biramous states are both found in T. corallicola .

In the absence of other characters to separate the two species, T. hirsutus is herein considered a junior synonym of T. corallicola .

Scotto & Gore (1981) described and illustrated the pleon of the first five zoeal stages of T. corallica (from Florida) with five somites and found that the number of pleonal somites was constant throughout all five stages. Manning & Kropp (1987: fig. 8e) illustrated the pleon of a male from Florida with five pleonal somites and telson. However, the illustration provided by Manning & Kropp (1987) is partial as it clearly only depicts the pleonal somites 2 to 5 and telson. Utinomi (1944: fig. 12D ) provided the illustration of the pleon of a male of T. corallicola from Tortugas (as Pseudocryptochirus corallicola ) with six pleonal somites and telson. Canário et al. (2015: fig. 4C) illustrated the male pleon of T. hirsutus with six somites and telson but never discussed the number of pleonal somites in T. hirsutus and T. corallicola as illustrated by Kropp & Manning. All male specimens from Brazil examined herein (Paraíba, Bahia, Trindade and Martin Vaz Archipelago, and São Paulo) were identical in having the male pleon of six somites and telson. The male USNM 231682 from Ascension Island also has a pleon of 6 somites.

In the female T. corallicola the coxae of P2–P5 are provided with a well-developed anterior lobe, somewhat less developed in the P2 coxa ( Fig. 44G ). The males are devoid of such coxal lobe.

Figures

FIGURE 12. A–C, Acanthonyx petiverii H. Milne Edwards, 1834, adult male, cl 16.7 mm, cw 11.5 mm (MZUSP 40595). A, B, Habitus, dorsal and ventral views, respectively. C, Detail of the carapace, dorsal view. D, Acanthonyx dissimulatus Coelho in Coelho & Torres, 1993, holotype male, cl 20 mm, cw 13.5 mm (MZUSP 6596). Arrows indicate in (C) the first branchial lobe well-developed and in (D) the characteristic hooked setae. Photographs (A–C) by A. Pol, (D) by J. Colavite.

FIGURE 44. A, D, Opecarcinus hypostegus (Shaw & Hopkins, 1977), after Kropp & Manning (1987: 11, fig. 5c; 12, fig. 6f, respectively). B, E, Kroppcarcinus siderastreicola Badaró, Neves, Castro & Johnsson, 2012, after Badaro et al. (2012: 522, fig. 3A; 523, fig. 4C, respectively). C, F, G, Troglocarcinus corallicola Verrill, 1908. C, F, after Kropp & Manning (1987: 16, fig. 7d; 17, fig. 8d, respectively). G, Female, cl 4.1 mm, cw 3 mm (USNM 1207444) paratype of T. hirsutus Badaró et al., 2012 (junior synonym of T. corallicola). A–C, Female cheliped sternite. D–F, First male gonopod. G, Semi-diagrammatic outline of the posterior region of the body, dorsal view. Note in (B) anterior margin of the sternite tuberculate (arrow) and in (G) the coxa of the fifth pereopod provided with a well-developed anterior lobe (arrow).

FIGURE 45. A–F, Troglocarcinus corallicola Verrill, 1908. A, B, Male, cl 2.8 mm, cw 2.3 mm (MZUSP 40210). C, D, Ovigerous female, cl 2.8 mm, cw 2.3 mm (MZUSP 40217). E, Day time, in situ photograph of a free-living male on a coral (Trindade Island,April, 2014). Note crab concealing itself by matching the color of the background. F, Day time, in situ photograph of crab inside its chamber in the coral host (Trindade Island, November, 2017). Note crescent-shaped dwelling opening. Photographs: (A–D) by A. Pol, (E, F) by J.B. Mendonça.