Antillesoma mexicanum Silva-Morales, López-Aquino, Islas-Villanueva, Ruiz-Escobar & Bastida-Zavala, 2019

Gómez-Vásquez, Julio D., 2024, New records and five new species of sipunculans (Sipuncula) from the central and northwestern Mexican Pacific, European Journal of Taxonomy 925, pp. 179-219 : 184-185

Antillesoma mexicanum Silva-Morales, López-Aquino, Islas-Villanueva, Ruiz-Escobar & Bastida-Zavala, 2019

Fig. 2

Antillesoma mexicanum Silva-Morales, López-Aquino, Islas-Villanueva, Ruiz-Escobar & Bastida-Zavala, 2019: 103–106, fig. 2 (type locality: Panteón Beach, Puerto Ángel, Oaxaca, México; in coral rubble, depth 2 m; southern Mexican Pacific).

Physcosoma antillarum (non Grube & Öersted in Grube, 1858). – Steinbeck & Ricketts 1941: 346, pl. 16 fig. 2 (Espíritu Santo Island and La Paz, Baja California Sur).

Antillesoma antillarum (non Grube & Öersted in Grube, 1858). – Fisher 1952: 434–436, pl. 39 figs 8–9. — Brusca 1980: 127 (reference from the Gulf of California).

Material examined

MEXICO – Baja California Sur • 1 spec.; La Paz , Calerita Beach ; intertidal; 1 Mar. 2006; DHP leg.; UMAR-SIPU 134. – Sinaloa • 2 specs; Mazatlan, Pinitos Beach ; 23°12ʹ28.02ʺ N, 106°25ʹ32.69ʺ W; 23 Feb. 2004; depth 1 m; PSS and MTH leg.; associated with sabellariid tubes; ECOSUR-S026. – Nayarit • 1 spec.; Litigú Cove ; 20°47ʹ21ʺ N, 105°31ʹ3ʺ W; 9 Apr. 1996; depth 3 m; EMU-13430 • 3 specs ; Sayulita Beach ; 20°47ʹ24ʺ N, 105°31ʹ54ʺ W; 10 Apr. 1996; depth 3 m; UMAR-SIPU 135 • 2 specs; Sayulita Beach; 20°52ʹ15ʺ N, 105°26ʹ40.4ʺ W; 28 Nov. 2004; depth 1 m; PSS et al. leg.; in rocks; ECOSUR-S0261 • 1 spec.; Banderas Bay, Manzanilla Beach ; 20°44ʹ25.49ʺ N, 105°23ʹ24.33ʺ W; 29 Nov. 2004; depth 1 m; PSS et al. leg.; in rocks; ECOSUR-0260 • 1 spec.; Mantanchen Bay, Aticama Beach ; 21°28ʹ49ʺ N, 105°12ʹ12ʺ W; 4 Nov. 2006; UMAR-SIPU 136. – Jalisco • 4 specs; San Patricio Melaque Beach ; 19°13ʹ08.82ʺ N, 104°42ʹ50.22ʺ W; 1 Dec. 2004; depth 1 m; PSS et al. leg.; in rocks; ECOSUR-S0264 • 1 spec.; San Patricio Melaque Beach; 19°13ʹ12.08ʺ N, 104°42ʹ49.95ʺ W; 2 Dec. 2004; depth 3 m; PSS et al. leg.; in rocks; ECOSUR-S0263 .

Description ( UMAR-SIPU 136)

Trunk up to 39 mm in length (range: 2.6–39 mm, n: 10), width 1/6 as long as trunk length; rough brownish skin, darker on anterior and posterior ends of trunk. Dark brown dome-shaped papillae scattered on entire trunk; packed on anterior and posterior ends. Introvert as long as ½ of trunk length, light brown; small conical papillae with rounded tip scattered on 80% of posterior introvert. Terminal end of introvert with a collar; with approximately 150 filiform tentacles, encircling nuchal organ.

Longitudinal musculature divided into 30 anastomosing bands; two pair of retractor muscles, attached to body wall at 80% of posterior trunk length, dorsal pair thinner than ventral pair. A pair of nephridia occupying ⅔ of trunk length, nephridiopores open posterior to anus. Contractile vessel with numerous villi. Spindle muscle attached posteriorly ( Fig. 2B ).

Habitat

Intertidal to subtidal (3 m); in rocks, in dead coral and associated with sabellariid tubes.

Distribution

Mexican Pacific: from Baja California Sur to Oaxaca ( Silva-Morales et al. 2019).

Remarks

The specimens coincide morphologically with the descriptions of Steinbeck & Ricketts (1941) and Fisher (1952), which were recorded as A. antillarum (Grube & Örsted in Grube, 1858). Recently, Silva-Morales et al. (2019) examined specimens from the Southern Mexican Pacific, and using morphological and molecular features they recognized a new species, leaving the populations of A. antillarum restricted to the Caribbean. Here, the morphological features of the examined specimens agree with those described by Silva-Morales et al. (2019) for A. mexicanum .

Figures

Fig. 2. Antillesoma mexicanum Silva-Morales, López-Aquino, Islas-Villanueva, Ruiz-Escobar & Bastida-Zavala, 2019 (UMAR-SIPU 136). A. Lateral overview, introvert everted. B. Internal anatomy; asterisk shows detached part of nephridum. Abbreviations: see Material and methods. Scale bars = 10 mm.