Chrysopetalum occidentale Johnson 1897
Creators: name: Cruz-Gómez, Christopher
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Phyllodocida
Chrysopetalidae
Chrysopetalum
Chrysopetalum occidentale

description: Chrysopetalum occidentale Johnson, 1897
Figs 22, 26
Chrysopetalum occidentale Johnson, 1897: 161–162, Pl. 5, Figs 15–16; Pl. 6, Figs 17–19.
Type locality: San Pedro Harbor, California, U.S.A., at 4.5 m (Johnson 1897).
Material examined. twenty-seven specimens. Baja California Sur: ECOSUR-2116, Terminal Lagoon, Bahía Concepción, on coarse sand, May 6, 1981, coll. HL; ECOSUR-2111, Morro Point, June 23, 1982, coll. SSV; UANL 0049, Requesón Beach, Bahía Concepción, July 19, 1985, coll. ALG; UANL 0047, 2 spec. Bahía Concepción, July 20, 1985, coll. ALG; UMAR-Poly 943, 4 spec. Bahía Concepción, May 15, 1988, coll. RBZ. Jalisco: ECO- SUR-2983, 2 spec. San Patricio Melaque, on rocks with sand, 1 m, December 1, 2004, coll. BY & PSS. Guerrero: UMAR-Poly 944, 14 spec. Coral Beach, 17º40´36”N, 101º39´22”W, Ixtapa, on dead coral, 1. 5 m, September 19, 2007, coll. SGM et al.; UMAR-Poly 945, Azul Beach, Coyula, September 20, 2007, coll. SGM et al. Oaxaca: ECOSUR-PXXX, La Entrega Beach, Huatulco, on stromatolite, 3 m, May 23, 2000, coll. SSV et al.; UMAR-Poly 946, Panteón Beach, 15º39´50”N, 96º29´43”W, on sediment, 3 m, May 21, 2008.
Description. Based on the best-preserved specimen (ECOSUR-2111): complete with 44 segments. TL= 5.6 mm, TW= 1.3 mm. Body long, broad, tapered posteriorly (Fig. 22A). Body pale whitish to pale yellow. Paleae fan bright yellow, slightly imbricated dorsally.
Prostomium visible between the first two segments. Lateral antennae short, inserted on the antero-ventral prostomial margin, median antenna shorter than lateral ones, inserted between the first pair of eyes. Eyes red-violet, two pairs. Nuchal organ, small, not covering the prostomium (Fig. 20B). Palps long, cylindrical, visible in dorsal view. Mouth fold large, placed between segment 3 and 4. Pharynx eversible, not exposed, stylets thick.
Parapodium from segment 30, notochaetae in three main groups (Fig. 22E). Notochaetae: lateral group inserted below notaciculum, 2–3 paleae, narrow and asymmetrical, with 2–3 internal ribs and 0–1 raised rib (Fig. 22F); subunit 1, 1 palea, broad and asymmetrical, with 4–5 internal ribs (Fig. 22G). Main group, 15–19 paleae; lateral-most paleae, broad and asymmetrical, with 5 internal ribs; mid-most paleae, symmetrical with 5–6 internal ribs; midlinemost paleae broad, asymmetrical, with 6 internal ribs (Fig. 22H). Median group, 3–4 paleae, shorter, slender and asymmetrical, with 4–5 (6) internal ribs and 0–1 raised rib (Fig. 22I–K). All paleal groups with margins finely serrated, and dorsal paleal surface ornamented with tiny tubercles.
Neuropodium conical, longer than notopodium. Neurochaetae: unit 1, 1–2 falcigers, blades straight and long, 7–8 times longer than wide (Fig. 22L). Unit 2, 4–5 falcigers, blades straight and medium-sized, 6–7 times longer than wide (Fig. 22M). Unit 3, 5–7 falcigers, blades straight and medium-sized, 6–7 times longer than wide (Fig. 22N). Unit 4, 3–4 falcigers, blades straight and medium-sized, 5–6 times longer than wide (Fig. 22O). Pygidium rounded with two anal cirri (Fig. 22C). Oocyte size: 58.4–83.3 µm (n=5) (Fig. 22D).
Habitat. Intertidal to subtidal (0.5–9.7 m). Specimens of C. occidentale were collected on sediment, rock, dead coral, and as epibiont on stromatolite. This species has been recorded as epibiont on bivalve, P. damicornis (Linnaeus, 1758), bryozoa, hydrozoa, tunicate, sponges, chaetopterids tubes, and as a member of the fouling community (Rioja 1941; Hartman 1961; Cruz-Gómez & Bastida-Zavala 2018).
Distribution. From San Pedro Harbor, California to Galápagos Islands (Johnson 1897; Monro 1933; Rioja 1941; Hartman 1961; Perkins 1985; Gómez et al. 1997; Dean et al. 2012; Cruz-Gómez & Bastida-Zavala 2018) (Fig. 26).
Remarks. Specimens revised herein agree with the description made by Perkins (1985), Aguado et al. (2003) and Cruz-Gómez & Bastida-Zavala (2018). Intraspecific differences were noted on northern specimens from Jalisco; these have large cirrophoral glands, which differs from the southern specimens from Oaxaca, whose glands are smaller. This condition is related to the maturity of the specimens (CW Pers. Comm. 2020).
description: Published as part of Cruz-Gómez, Christopher, 2021, A new genus and seven new species of chrysopetalids (Annelida, Chrysopetalidae) from the Tropical Eastern Pacific, pp. 1-59 in Zootaxa 5068 (1) on page 43, DOI: 10.11646/zootaxa.5068.1.1, http://zenodo.org/record/5702007