Themiste (Themiste) hennahi Gray, 1828

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 : 197-198

Themiste (Themiste) hennahi Gray, 1828

Fig. 6G

Themiste hennahi Gray, 1828: 8 , pl.6 fig 4, 4a (type locality: Perú).

Dendrostoma mytheca Chamberlin, 1920: 30–31 (type locality: Laguna Beach California, on algae).

Dendrostoma zostericola Chamberlin, 1920: 30 (type locality: Laguna Beach, California, within algae).

Dendrostomum lissum Fisher, 1952: 419–422 , pl. 35 (type locality: Punta Lobos, Espíritu Santo Island, Baja California Sur, intertidal).

Dendrostomum schmitti Fisher, 1952: 422 , fig. 87f (type locality: Independencia Bay, Perú).

Dendrostma zostericola – Fisher 1952: 411–415, pl. 30 fig. 1, pls 31–32 (as Dendrostomum zostericolum ; Ensenada, Baja California, intertidal, algal rhizoids, gravel and sand under rocks, and in muddy sand).

Themiste (Themiste) hennahi – Cutler & Cutler 1988: 742, 753–755, table 1 (new combination). — Silva-Morales & Gómez-Vásquez 2021: 86–88 , fig. 5 (San Agustín Bay, Oaxaca, inhabiting Porites sp. ).

Material examined

MEXICO – Baja California • 1 spec.; Los Ángeles Bay ; 28°56ʹ55.48ʺ N, 113°33ʹ26.36ʺ W; 25 May 1989; SSV and JLG leg.; ECOSUR-S0255 . – Nayarit • 21 specs; Banderas Bay, Manzanilla Beach ; 20°44ʹ25.49ʺ N, 105°23ʹ24.33ʺ W; 29 Nov.2004; depth 2m; PSS et al. leg.; under rocks; ECOSUR-S0253 . – Jalisco • 2 specs; Barra de Navidad, Corrales Beach ; 19°11ʹ14.08ʺ N, 104°41ʹ42.84ʺ W; 3 Dec. 2004; depth 4 m; PSS et al. leg.; under rocks; ECOSUR-S0254 .

Description

Trunk 6 mm in length, pyriform, caudal region nipple-like; smooth light brown body wall, with small, flat oval papillae. Introvert as long as trunk; tentacular crown with six stems, each one divided into two branches, branches with 10 terminal tentacles; tentacles pigmented in dark patches.

Longitudinal musculature continuous; two retractor muscles attached at 75% of trunk length; contractile vessel with 15 long tubules. Two nephridia 25% of trunk length; nephridiopores posterior to anus. Spindle muscle present, not attached to intestine posteriorly.

Variations

The specimens examined had a trunk length range between 2 and 12 mm. The number of tentacles varies with length, a specimen with a trunk length of 2 mm having eight terminal tentacles on each branch, while a specimen with a trunk length of 6 mm has 10 terminal tentacles on each branch of the tentacular crown; the largest specimen measured here has a trunk length of 12 mm and it has 14 terminal tentacles on each branch. Considering all specimens, the total amount of tentacles is between 72 and approximately 170.

Habitat

Intertidal to subtidal (4 m); under rocks, between algal rhizoids, in gravel and muddy sand.

Distribution

Eastern Pacific: from California to Perú.

Remarks

The specimens agree with the descriptions made by Gray (1828) and Fisher (1952). This species has previously been recorded from the study area in the Gulf of California.

Figures

Fig. 6. Golfingids. A. Golfingia (Golfingia) cf. muricaudata (EMU-13446). B–E. Nephasoma (Nephasoma) wodjanizkii wodjanizkii (Murina, 1973) (UMAR-SIPU 133). B. Lateral overview. C. Lateral view of posterior introvert. D. Internal anatomy. E. Close-up of retractor muscle origins from body wall. F. Themiste (Themiste) cf. blanda (ECOSUR-S0256). G. T. (T.) hennahi Gray, 1828 (ECOSUR-S0255). H. T. (T.) pyroides Chamberlin, 1920 (UMAR-SIPU 130). Abbreviations: see Material and methods. Scale bars: A = 2 cm; B, H = 2 mm; C, E = 1 mm; D, F = 4 mm; G = 3 mm.