Apionsoma (Apionsoma) silviae, Gómez-Vásquez, 2024

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 : 199-201

Apionsoma (Apionsoma) silviae sp. nov.

urn:lsid:zoobank.org:act:82A61D62-E27F-4D35-B1F2-85BEC0319CD0

Figs 8–9

Etymology

This species is named after the author’s beloved mother, Silvia Vásquez Martínez, for all the effort and support she has given her sons, which has given them the opportunity to study and dedicate themselves to their favourite interests. The epithet is a noun in the genitive case ( ICZN 1999, ART. 31.1.2).

Material examined

Holotype

MEXICO • 1 spec.; Gulf of California ; 28°20ʹ57ʺ N, 112°37ʹ16ʺ W; 11 Apr. 2011; depth 310 m; corer; TALUD XIV cruise, stn 16, on board R/V El Puma; EMU-13436 .

Description (EMU-13436)

Trunk 8 mm in length; rough, light brown body wall, with numerous scattered, mammillate papillae ( Fig. 8A ), decreasing in size towards caudal region, with a spiral effect in caudal region ( Fig. 8C ). Introvert partially everted, four times as long as trunk length, with 10 small digitiform tentacles encircling nuchal organ dorsal to mouth. Hooks 30 µm long, with four basal spinelets, arranged in ten complete rings. Scattered, ventrally and dorsally, Mammillate papillae present ventrally and dorsally, scattered; two dorsolateral longitudinal lines of papillae at 80% of posterior introvert ( Fig. 8B ); ventral papillae smaller in size.

Longitudinal musculature continuous; four retractor muscles attached at 50% of trunk length ( Fig. 9A ); retractor muscles equally displaced from nerve cord; dorsal retractor muscles anterior to ventral pair. A pair of bilobed nephridia, 3 mm long, anterior lobe one-fifth as long as posterior lobe; nephridiopores anterior to anus. Spindle muscle present; not attached to intestine in caudal region of trunk.

Habitat

Bathyal (310 m); in muddy sand.

Distribution

Only known from stn 16 of the TALUD XIV cruise, near Cabo San Miguel, Baja California.

Remarks

The sole specimen examined is easily placed in the subgenus Apionsoma (Apionsoma) by the presence of a continuous longitudinal musculature, which is very similar to conditions in the two subspecies A. (A.) murinae murinae (Cutler, 1969) , described from the north-west Atlantic, and A. (A.) murinae bilobatae (Cutler, 1969), described from the north Atlantic. However, A. (A.) silviae shows differences to both subspecies by having bilobed nephridia and in the arrangement of the papillae on the introvert and on the caudal region.

Figures

Fig. 8. Apionsoma (Apionsoma) silviae sp. nov. (EMU-13436). A. Lateral overview, introvert partially everted. B. Posterior part of introvert. C. Posterior part of trunk.Abbreviation: see Material and methods. Scale bars: A = 3 mm; B–C = 1 mm.

Fig. 9. Apionsoma (Apionsoma) silviae sp. nov. (EMU-13436). A. Internal anatomy. B. Illustration of internal anatomy. Abbreviations: see Material and methods. Scale bar = 2 mm.