Themiste (Themiste) pyroides ( Chamberlin, 1920 )

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 : 198-199

Themiste (Themiste) pyroides ( Chamberlin, 1920)

Fig. 6H

Dendrostoma pyroides Chamberlin, 1920: 3 (type locality: Laguna Beach, California; intertidal).

Dendrostoma pyroides – Fisher 1952: 406–409, pl. 27 figs 1–2, pl. 28 fig. 2, pl. 29 (Ensenada and San Quintin Bay, Baja California).

Themiste pyroides – Adrianov et al. 2006: 577–579, figs 1c–d, 7–10 (Vostok Bay, Sea of Japan).

Material examined

MEXICO – Baja California Sur • 1 spec.; La Paz Bay , El Caimancito Beach ; 24°12ʹ10.43ʺ N, 110°18ʹ01.09ʺ W; 28 Nov. 1986; depth 2 m; SSV leg.; under rocks; ECOSUR-S0251 • 8 specs; La Paz Bay , El Caimancito Beach ; 24°12ʹ15ʺ N, 110°18ʹ02.96ʺ W; 29 Feb. 2004; depth 1 m; PSS and MTH leg.; inhabiting Porites sp. ; ECOSUR-S0252 • 1 spec.; La Paz Bay , Calerita Beach ; 1 Mar. 2006; DHP et al. leg.; UMAR-SIPU 130 . – Sinaloa • 1 spec.; Mazatlan, Pinitos Beach ; 23°12ʹ28.022 N, 106°25ʹ32.69ʺ W; 3 Feb. 2004; depth 1 m; PSS and MTH leg.; associated with sabellariid tubes; ECOSUR-S0258 .

Description ( UMAR-SIPU 130)

Trunk 12 mm in length, pyriform, caudal region pointed; smooth, light brown body wall, with small, flat oval papillae. Introvert as long as 0.75 of trunk length, with pigmented collar and tentacular crown base; tentacular crown with four stems divided into two branches, stems of ventral pair slightly longer than those of dorsal pair; each branch with eight terminal tentacles. Small, dark, claw-like hooks at posterior introvert.

Longitudinal musculature continuous; two retractor muscles attached to body wall at 50% of trunk length; contractile vessel with 15 tubules. Two nephridia, of 25% of trunk length; nephridiopores before anus. Spindle muscle present, attached to intestine anteriorly and to trunk posteriorly.

Habitat

Intertidal to subtidal (1–2 m); under rocks, inhabiting Porites sp. , and associated with sabellariid tubes.

Distribution

Eastern Pacific: from California to the Gulf of California.

Remarks

Themiste (T.) pyroides may be confused with T. (T.) blanda ( Selenka & de Man, 1883) ; however, the main difference between the species concerns the tentacular crown. Themiste (T.) blanda has the branches symmetrically divided, in addition to bearing tentacles along the inner face of the stems and branches, whereas T. (T.) pyroides only has terminal tentacles and the branches are not divided symmetrically. According to Cutler (1994), T. (T.) pyroides is distributed in the eastern Pacific, from southern Alaska ( Frank 1983) to the western coast of Baja California ( Fisher 1952); however, the Alaska record should be reviewed, because the temperature range tolerance for this species has not been investigated and it seems unlikely that a subtropical species such as T. (T.) pyroides would occur at such low temperatures. Furthermore, there are no records of this species farther north than its type locality, apart from Frank’s record ( Frank 1983). In the northwestern Pacific of Mexico, T. (T.) pyroides extends its distribution from the west coast of Baja California to the Gulf of California (Sinaloa).

Themiste (T.) pyroides has also been recorded from the Sea of Japan ( Adrianov et al. 2006, 2008); however, the latter study was based on a molecular analysis and concluded that the eastern and western populations are two distinct clades at the molecular level ( Schulze et al. 2012). This may suggest that both populations could be part of a species complex, which should be addressed using morphological and molecular evidence.

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.