Semiodera salazarae, Salazar-Vallejo, 2012

Salazar-Vallejo, Sergio I., 2012, 3562, Zootaxa 3562, pp. 1-62 : 33

Semiodera salazarae n. sp.

Figure 12

Type material. Eastern Tropical Pacific, Mexico. Holotype ( ECOSUR 138 ) and paratype ( ECOSUR 139 ), Playa La Manzanilla (20°44'35" N, 105°23'14.8" W), Nayarit, mixed bottoms, 1 m depth, 29 Nov. 2004, P. Salazar, coll. (paratype mature female, anterior fragment, 7 mm long, 2 mm wide, cephalic cage broken, 2.5 mm long, 29 chaetigers; oocytes 120–150 µm).

Description. Holotype (ECOSUR 138) complete, dark yellowish, recurved dorsally ( Fig. 12A). Body cylindrical, tapering posteriorly into a long, thin cauda; 12 mm long, 2 mm wide, cephalic cage 4 mm long, 55 chaetigers. Tunic thin, without sediment cover; body papillae large, capitate, arranged in 5–7 rows per segment ( Fig. 12D), without interramal papillae.

Anterior end not exposed; not dissected to avoid further damage. Cephalic cage chaetae partially broken, twice as long as body width. Chaetigers 1–2 involved in cephalic cage; chaetae arranged in short rows, about the body corners; chaetiger 1 with 4 noto- and 3 neurochaetae per ramus, chaetiger 2 along same axis as chaetiger 1, with 3 noto- and 2 neurochaetae per ramus.

Anterior dorsal margin of chaetiger 1 projected anteriorly (eroded in paratype), without papillae. Anterior chaetigers without especially long papillae (paratype with chaetiger 1 with longer papillae in neurochaetal bases). Chaetigers 1–2 slightly shorter than chaetiger 3. Sand cemented anterior shield ( Fig. 12B–D) extending posteriorly into chaetiger 6 (5 in paratype), and ventrally along chaetigers 1–2, reaching the midventral line. Chaetal transition from cephalic cage chaetae to body chaetae gradual; pseudocompound hooks in chaetigers 3–8. Falcate simple neurohooks from chaetiger 9. Gonopodial slits not visible.

Parapodia poorly-developed, chaetae emerge from body wall. Parapodia lateral, median neuropodia ventrolateral. Noto- and neuropodia without projections, lobes or longer papillae. Noto- and neuropodia well separated from each other.

Median notochaetae variously broken, about as long as ¼–1/5 body width, multiarticulate capillaries, articles short basally, medium sized along a short region, long throughout most of chaeta. Neurochaetae multiarticulate capillaries in chaetigers 1–2; neuropodia 3–8 with long pseudocompound hooks, 2 per ramus, often broken ( Fig. 12E, insert), decreasing in size posteriorly; falcate golden neurohooks from chaetiger 9, arranged in transverse rows, 2 per ramus in most chaetigers, including subterminal ones. Hooks golden, homogeneously pigmented, with many, delicate transverse bands ( Fig. 12F). Posterior end tapering into a hemispheric lobe; pygidium with terminal anus, no anal cirri.

Etymology. The species name is derived from my colleague Dr. Patricia Salazar-Silva in recognition of her efforts to encourage taxonomic studies of marine invertebrates in tropical Mexico, and because she collected these described specimens..

Type locality. Western Mexico. Playa La Manzanilla , Nayarit, 1 m depth, mixed bottoms

Remarks. Semiodera salazarae n. sp. groups with S. nishi n. sp. and S. treadwelli n. sp. as all have a poorlydeveloped dorsal shield and two neurohooks in median chaetigers. Unlike the other species, S. nishi has neurohooks from chaetiger 8 (as opposed to chaetiger 9), rendering S. salazarae more closely allied to S. treadwelli . These two species differ in that the dorsal shield of S. salazarae is covered with large densely packed sand grains, whereas in S. treadwelli they are small, sparse particles. Further, the ventral extension of the dorsal shield differs because in S. salazarae the shield lateral projections are ventrally connected, whereas in S. treadwelli these projections do not reach the midventral line.

Distribution. Apparently restricted to the Mexican Central Pacific coasts in the state of Nayarit, in intertidal mixed bottoms.