Antillesoma antillarum (Grübe & Oersted, 1858)

Phascolosoma antillarum Grübe & Oersted, 1858:117–118 .— Fisher 1952:434–436, plate 39, figs 8–9; Rice & Macintyre 1972:42.

Physcosoma antillarum Gerould, 1913:420–421, plate 62, figs 19–20.

Phascolosoma (Antillesoma) antillarum Stephen & Edmonds, 1972:278–279, figs 35D–F.— Rice 1970:42, fig. 5; Young 1986:103; Cutler & Cutler 1983:182–184.

Antillesoma antillarum .— Cutler et al. 1992:156, fig. 3B; Cutler 1994:1868–189, fig. 52; Dean 2001:87–88; Cutler & Schulze 2004:226; Schulze & Rice 2004:4; Collin et al. 2005: 688; Matthewes-Cascon & Lotufo 2006:69; Dean et al. 2007:50; Varela & Schulze 2008:9; Garcia et al. 2010:10, fig. 3c; Díaz-Díaz 2011:169; Gómez et al. 2013: 58–6; Quirós-Rodríguez et al. 2021: 1201–1203, fig. 3.

Examined Material: Brazil. UFPB-SIP 88, 2 specs.; Rio Grande do Norte, Nísia Floresta, Pontal de Tabatinga, 6°3’11”S, 35°6’24”W, coll. Aug. 1982 by M.L. Christoffersen; INV-2400008, 1 spec.; Ceará, Fortaleza, Praia de Sabiaguaba, 3°48’35”S, 38°24’35”W, coll. 2013 by C. Mendes ; MZUSP5373, 6 specs; Pernambuco, João Pessoa, 7°08’54”S, 34°47’52”W, coll. 2 Dec. 1979 by M. L. Christoffersen; UFMG-INV-2400001–2400007, 7 specs; Pernambuco, Praia do Paraíso, Cabo de Santo Agostinho, 8°21’11”S, 34°55’35”W, coll. Apr.2018 by G.Y. Kawauchi ; MZUSP5372, 2 specs; Alagoas, Maceió, 9°38’55”S, 35°42’20”W, coll. 7 Nov. 1972 ; MZUSP5380, 36 specs; Bahia, Boipeba, Praia de Bainema, 13°37’48”S, 38°53’50”W, coll. 16 Oct. 2011 by M. Tavares ; MZUSP5371, 19 specs; Bahia, Boipeba, Tassimirim, 13°34’52”S, 38°54’49”W, coll. 15 Oct. 2011 by M. Tavares ; MZUSP5376, 14 specs; Bahia, Boipeba, Praia de Bainema, 13°37’49”S, 38°53’50”W, coll. 15 Apr. 2012 by M. Tavares ; MZUSP5379, 1 spec.; Bahia, Boipeba, Praia dos Castelhanos, 13°39’08”S, 38°53’29”W, coll. 16 Oct. 2010 by M. Tavares; A. Benetti; J. Braga; L. Ferreira & A. Gouvea; MZUSP5370, 2 specs; Bahia, Boipeba, Foz Rio Catu, 13°39’33”S, 38°53’58”W coll. 16 May 2012 by M. Tavares ; MZUSP5378, 5 specs; Bahia, Boipeba, Praia dos Castelhanos, 13°39’55”S, 38°53’52”W, coll. 17 Apr. 2012 by M. Tavares ; MZUSP5366, 2 specs; Bahia, Porto Seguro, Coroa Vermelha, 16°19’59”S, 39°00’22”W, coll. 13 Nov. 2010 by M. Tavares; A. Benetti; J. Braga; L. Ferreira & A. Gouvea ; MZUSP5374, 2 specs; Bahia, Porto Seguro, Coroa Vermelha, 16°19’58”S, 39°00’21”W, coll. 30 May 1994, Diversitas Neotropica expedition ; MZUSP5379, 1 spec.; Bahia, Porto Seguro, Ponta Grande, 16°22’38”S, 39°00’20”W, coll. 16 Nov. 2010 by M. Tavares; A. Benetti; J. Braga; L. Ferreira & A. Gouvea ; MZUSP5479, 1 spec.; Espírito Santo, Vitoria, Ilha de Trindade, Enseada dos Portugueses, 20°29’52.3”S, 29°19’15.6”W, coll. Jul. 2013 by J.B. Mendonça ; MZUSP5478, 2 specs; Espírito Santo, Vitoria, A Ilha de Trindade, Ilha da Racha, 20º30’26.5”S, 29°0’48.0”W, coll. Jul. 2013 by J.B. Mendonça ; MZUSP5491, 1 spec.; Espírito Santo, Ilha de Martim Vaz, 20°30’45.7”S, 29°18’21.9”W, coll. 24 Jul. 2012 by J.B. Mendonça ; MZUSP5476, 1 spec.; Espírito Santo, Vitoria, Ilha de Trindade, Enseada da Cachoeira, Farilhões, 20°31’22.4”S, 29°19’52”W, coll. Jun. 2012 by J.B. Mendonça ; MZUSP5481, 1 spec.; Espírito Santo, Vitoria, Ilha de Trindade, Enseada da Cachoeira Farrilhões, 20º31’22.4”S, 29º19’52”W, coll. Jul. 2012 by J.B. Mendonça ; MZUSP5484, 1 spec.; Espírito Santo, Vitoria, Ilha de Trindade, Enseada da Cachoeira Farrilhões, 20°31’22.4”S, 29°19’52”W, coll. Jun. 2012 by J.B. Mendonça ; MZUSP5369, 2 specs; Espírito Santo, Guarapari, Praia Peracanga, 20°40’45”S, 40°30’4”W, coll. 10 Jan. 1978 by M. L. Christoffersen.

Diagnosis: External anatomy (Fig. 3A). Body measuring 38± 16 mm in length (N=20). Introvert (distended): 9± 5 mm length (N=20), covered with conical papillae (some of them pointing to the posterior region (Fig. 3I)), ratio between introvert diameter and introvert length 1:4 (1:38–1:7). Tentacles>40, digitiform purplish or greenishbrown. Trunk: 30± 12 mm length (N=31), pinkish or dark brown, and covered by papillae divided into three regions - anterior: rounded dark papillae; medial: small light papilla; posterior: rounded dark papillae (Fig. 4). Ratio between trunk diameter and trunk length 1:7 (1:38–1:17). The proportion introvert/trunk length is ~ 30%. Anus opening at 2± 1 mm (N=28) from the anterior region of the trunk.

Internal anatomy (Fig. 3B). Internal trunk with longitudinal muscles in anastomosing bundles beginning 12± 5 mm (N=24) from anterior region of the trunk; anterior region with 12–19 LMBs (N=34), 21–36 LBMs (N=23) at base of retractor muscles, and posterior end with 19–35 LBMs (N=22). Nephridia opening immediately posterior to anus, between 2–3 (N=21), 3-4 LMBs (N= 2), measuring 17± 9 mm (N=21) and 14± 3 mm (N=21) in length attached to the trunk wall, brownish-yellow to orange in color. Two pairs of introvert retractor muscles fixed to the trunk 17± 4 mm (N=20) from the anterior region of trunk, ventral pair attached between 1–5 (N=2), 2–5 (N=1), 2–7 (N=1), 3–6 (N=3), 3–7 (N=1), dorsal pair attached between 6–8 (N=1), 6–9 (N=3), 6–10 (N=1),8–9 (N=1), 8–10 (N=3). Spindle muscle attached immediately anterior to anus. Fixing muscle originates from the spindle muscle at 2 nd intestinal coil attached to left side of ventral nerve cord, 18± 8 mm (N=7) from anterior region. Wing muscle extends from anus in both left and right directions, covering 3 (N=8), 4 (N=9), or 5 (N=1) LMBs. Contractile vessel covered by digitiform villi, reddish or whitish in color.

Taxonomic Remarks: The external and internal anatomy of A. antillarum from Brazil closely follows the descriptions provided by Gerould (1913), Fisher (1952), and Cutler (1994) and Franco et al. (2024) for specimens collected from various locations along the Western Atlantic coast. With regards to coloration, our observations contrast with Cutler (1994), who described a brownish-green tentacle pattern only for fixed specimens. We have observed this coloration pattern within fixed and live individuals collected in Praia da Pituba, Salvador, Bahia. All specimens from Praia do Paraíso, Cabo de Santo Agostinho, Pernambuco, exhibit brownish-green tentacles in fresh specimens and were found under rocks. Variations in trunk coloration patterns were noted, with individuals displaying a pinkish-reddish (on museum specimens (Fig. 4A–D) or brownish (on live and fixed animals (Fig. 4E–I) pattern. It was also observed that the shape and distribution of papillae along the trunk exhibit considerable variation between individuals (Fig. 4). The coloration of the contractile vessel villi also exhibited variability, with white villi observed in both fresh and long-preserved specimens, while the reddish pattern was limited to specific individuals within the museum specimens. The high variation in the total count of LMBs along the trunk was also observed due to the high degree of anastomosis, resulting in variations in the position of the introvert retractor along the LMBs.

Distribution (Fig. 2): Antillesoma antillarum has been documented in locations across Indo-West Pacific, Eastern Pacific on the Eastern and Western Atlantic (Cutler 1994). In Brazil it occurs from Praia de Flecheiras, Trairi, Ceará (Matthewes-Cascon & Lotufo 2006); Fortaleza, Ceará; Maracajaú, Rio Grande do Norte (Garcia et al. 2010); Nísia Floresta, Rio Grande do Norte; João Pessoa, Paraíba (Young 1986); Pernambuco (Gerould 1913); Cabo de Santo Agostinho, Pernambuco; Maceió, Alagoas; Salvador, Bahia (Franco et al. 2024); Boipeba, Bahia; Porto Seguro, Bahia; Coroa Vermelha, Bahia; Guarapari, Espírito Santo; Arquipélago Trindade e Martim Vaz, Espírito Santo.