Eurythoe spirocirrata Essenberg, 1917

Tovar-Hernández, María Ana, González-Vallejo, Norma Emilia & Salazar-Vallejo, Sergio I., 2024, Cryptonome beatrizae n. sp., from drifting wood in Western Mexico, with remarks on Pareurythoe Gustafson, 1930 (Annelida, Amphinomidae), Zootaxa 5424 (5), pp. 535-553 : 549-550

publication ID	https://doi.org/10.11646/zootaxa.5424.5.3
publication LSID	lsid:zoobank.org:pub:906DD43A-648B-4777-B6AB-9D16491377CE
DOI	https://doi.org/10.5281/zenodo.14895737
persistent identifier	https://treatment.plazi.org/id/F447F871-7925-5969-DE81-C0C9FA4AFD76
treatment provided by	Plazi (2025-02-19 21:43:40, last updated 2025-02-26 15:24:50)
scientific name	Eurythoe spirocirrata Essenberg, 1917
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Eurythoe spirocirrata Essenberg, 1917 View in CoL

Eurythoe spirocirrata Essenberg, 1917: 66-68 View in CoL , Pl. 4, Figs 15-17, Pl. 5, Figs 18-23.

Pareurythoe spirocirrata View in CoL : Hartman 1968: 201-202, 5 figs redrawn from original (n. comb.).

Diagnosis. Eurythoe with caruncle cushion-shaped, posteriorly bifid, reaching chaetiger 3; branchiae from chaetiger 1.

Type material. Holotype ( LACM 93 About LACM ); type locality unknown.

Morphological features. Holotype complete, bent ventrally, with right parapodia of first few chaetigers previously removed; 55 mm long, 13 mm wide (by chaetiger 30), 66 segments. Prostomium ( Fig. 10A, B View FIGURE 10 ) has median antenna shorter than laterals, inserted anteriorly to laterals, and lateral antennae as long as palps; eyes not seen (even in the original description). Caruncle roughly rectangular, longer than wide, with a transverse furrow medially, and its posterior margin bifid, reaching chaetiger 3; lateral lobes barely projected beyond lateral margins. Parapodia with articulated cirri; first few chaetigers with articulations symmetrical, followed by oblique articulations, looking arranged in spiral (hence the name); ventral cirri articulated in anterior chaetigers, smooth in median and posterior ones. Branchiae along body, present from chaetiger 1 ( Fig. 10C View FIGURE 10 ), with about 15 filaments, becoming larger and with more filaments in following chaetigers ( Fig. 10D View FIGURE 10 ), immediately followed by a marked abundance of filaments, covering space over dorsal cirri and between cirri ( Fig. 10E View FIGURE 10 ). Chaetae not illustrated; notochaetae originally described as thin spurred capillaries, and harpoon-chaetae, and neurochaetae furcates with very small shorter tines.

Remarks. Eurythoe spirocirrata Essenberg, 1917 was described with a large oval, longer than wide, posteriorly split caruncle, and with multiarticulated (or spirally arranged articles) parapodial cirri. Bindra (1927: 5) included E. spirocirrata in his key to species, but because of some missing details in the original description, such as the start of branchiae, Bindra regarded this species as having branchiae from chaetiger 2. Gustafson (1930) did not include the papers by Essenberg or Bindra, and Hartman (1940: 203) indicated E. spirocirrata might belong in Pareurythoe but there was no further comment on the species up to her Atlas ( Hartman 1968), where she regarded it as belonging in Pareurythoe . The study of the type specimen of E. spirocirrata helps clarify this issue and it is being regarded as belonging to Eurythoe because its caruncle is cushion-shaped, longer than wide, and not sigmoid. In fact, Essenberg (1917: 66) indicated the caruncle was “broad, smooth, extending to fourth segment”, and the discrepancy of having it to the third chaetiger is explained because the prostomium used to be counted as a segment.

Eurythoe spirocirrata resembles E. mathaii Bindra, 1927 from Karachi, India because both species have median antenna shorter than laterals, branchiae from chaetiger 1 and multiarticulated parapodial cirri. The main difference is that in E. spirocirrata the caruncle is roughly rectangular, whereas in E. mathaii it is oval. Other details require the study of specimens belonging to E. mathaii , and that is beyond our current objectives.

References

Bindra, S. S. (1927) A study of the genus Eurythoe (Family Amphinomidae). Fauna of Karachi, Memoirs of the Department of Zoology, Panjab University, 1, 1-18.

Essenberg, C. (1917) New species of Amphinomidae from the Pacific coast. University of California Publications in Zoology, 18 (4), 61-74.

Gustafson, G. (1930) Anatomische studien uber die polychaten-familien Amphinomidae und Euphrosynidae. Zoologiska bidrag fran Uppsala, 12, 305-471.

Hartman, O. (1940) Polychaetous annelids. Part II: Chrysopetalidae to Goniadidae. Allan Hancock Pacific Expeditions, 7 (3), 173-287.

Hartman, O. (1968) Atlas of the Errantiate Polychaetous Annelids from California. Allan Hancock Foundation, University of Southern California. Los Angeles, California, 828 pp.

Figures

FIGURE 10. Eurythoe spirocirrata Essenberg, 1917, holotype (LACM 93). A. Anterior end, dorsal view (Ca, caruncle, Pa, palp; numbers refer to dorsal cirri of successive chaetigers). B. Same, slightly oblique dorsal view, after Methyl green staining (Ca, caruncle; LA, lateral antenna; Pa, palp). C. Chaetiger 1, right parapodium, anterior view, after Shirlastain-A staining. D. Chaetiger 2, right parapodium, anterior view, same staining. E. Chaetiger 3, right parapodium, anterior view, same staining. Scale bars: A, 0.65 mm; B, 0.56 mm; C, 0.19 mm; D, 0.32 mm; E, 0.33 mm.