Eurythoe spirocirrata Essenberg 1917
Creators: name: Tovar-Hernández, María Ana
name: González-Vallejo, Norma Emilia
name: Salazar-Vallejo, Sergio I.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Amphinomida
Amphinomidae
Eurythoe
Eurythoe spirocirrata

description: Eurythoe spirocirrata Essenberg, 1917
Eurythoe spirocirrata Essenberg, 1917: 66-68, Pl. 4, Figs 15-17, Pl. 5, Figs 18-23.
Pareurythoe spirocirrata: 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); 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) 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), with about 15 filaments, becoming larger and with more filaments in following chaetigers (Fig. 10D), immediately followed by a marked abundance of filaments, covering space over dorsal cirri and between cirri (Fig. 10E). 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.
description: Published as part of 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), pp. 535-553 in Zootaxa 5424 (5) on pages 549-550, DOI: 10.11646/zootaxa.5424.5.3, http://zenodo.org/record/14895739