Aspidosiphon (Aspidosiphon) elegans ( Chamisso & Eysenhardt, 1821 )

Silva-Morales, Itzahí & Gómez-Vásquez, Julio D., 2021, First records and two new species of sipunculans (Sipuncula) from the Southern Mexican Pacific, European Journal of Taxonomy 740 (1), pp. 77-117 : 97-99

Aspidosiphon (Aspidosiphon) elegans ( Chamisso & Eysenhardt, 1821)

Fig. 11

Sternaspis elegans Chamisso & Eysenhardt, 1821: 351–352 , pl. 24, fig. 5a–e (type locality: Radack, Marshall Islands).

Material examined

MEXICO – Guerrero • 14; Ixtapa Island , Coral Beach; 17°40′37″ N, 101°39′20″ W; 19 Sep. 2007; SGM leg.; in algae; UMAR-SIPU 073 . – Oaxaca • 8; La Tijera Beach; 15°41′15″ N, 96°26′33″ W; 30 Apr. 2005; UMAR-SIPU 074 • 1; same locality as for preceding but 12 Sep. 2006; UMAR-SIPU 078 • 3; Estacahuite Beach ; 15°40′05″ N, 96°28′53″ W; 10 Sep. 2005; in dead coral; UMAR-SIPU 075 • 2; same locality as for preceding but 20 Sep. 2005; in dead coral; UMAR-SIPU 076 • 5; same locality as for preceding but 15 Aug. 2006; depth 4 m, in dead coral; UMAR-SIPU 077 • 2; Chachacual Bay, Jicaral Beach ; 15°42′39″ N, 96°12′11″ W; 10 Feb. 2007; depth 6.1 m, in Porites sp.; UMAR-SIPU 079 • 5; Panteón Beach ; 15°39′50″ N, 96°29′42″ W; 16 Apr. 2008; JDG and GGG leg.; depth 3 m, in dead coral; UMAR-SIPU 080 • 1; Puerto Ángel Bay ; 15°39′56″ N, 96°29′29″ W; 16 Apr. 2008; depth 3 m; UMAR-SIPU-081 .

Comparative material

MEXICO – Quintana Roo • 1; Xahuayxol ; 26 Sep. 1996; ECOSUR-S0121 • 1; Contoy Island, Punta Sur ; 2 Mar. 2001; in dead coral; ECOSUR-S0124 • 1; Mahahual ; 22 Mar. 2000; in dead coral; ECOSUR-S0128 • 3; Nizuc ; 30 Aug. 1999; depth 2.2 m, in rock with Dyctiota; ECOSUR-S0129 .

Description

Trunk 8 mm in length, white ( Fig. 11A ). Introvert three times the trunk length. Anal shield without grooves, caudal shield absent. Fourteen rings of bidentate compressed hooks ( Fig. 11C–D ) followed by scattered unidentate, dark, conical hooks ( Fig. 11E–F ). Longitudinal muscle of body wall in uniform continuous layer. A pair of retractor muscles originate at about 50% of trunk length. A pair of nephridia, unilobed, at 60% of trunk length. Spindle muscle attached posteriorly ( Fig. 11B ).

Remarks

The original description by Chamisso & Eysenhardt (1821) did not include a description of the hooks; thus, we cannot compare our specimens with the original description. Nevertheless, a revision is necessary because it is likely that the population of the Marshall Islands is different from the one of the SMP. This species has been recorded from Cocos Island, Costa Rica ( Dean et al. 2010). We did not find differences between the species in the SMP and the Mexican Caribbean ( Fig. 11G–J ).

Habitat

Intertidal to subtidal (4 m); in algae and dead coral ( Porites ).

Distribution

Widespread and common in the Indian and western Pacific Oceans, from south-central Japan to northern Australia to Hawaii, the Red Sea, and Israel. In the Caribbean from northern Brazil to the Florida Keys and Bermuda ( Cutler 1994). In the Eastern Pacific from the South Mexican Pacific to Costa Rica ( Fonseca & Cortés 1998; Dean et al. 2010).

Figures

Fig. 11. Aspidosiphon (Aspidosiphon) elegans (Chamisso & Eysenhardt, 1821). A–F. From the Southern Mexican Pacific. A. External morphology. B. Internal morphology. C. Bidentate hooks of proximal rings. D. Bidentate hooks of distal rings. E. Anterior conical hooks. F. Posterior conical hooks. G–J. From the Mexican Caribbean. G. Bidentate hooks of proximal rings. H. Bidentate hooks of distal rings. I. Anterior conical hooks. J. Posterior conical hooks. Abbreviations: I = intestine; LM = longitudinal muscle; N = nephridium; RM = retractor muscles.