Halosydna nesiotes (Chamberlin, 1919)

Salazar-Silva, Patricia, 2013, Revision of Halosydna Kinberg, 1856 (Annelida: Polychaeta: Polynoidae) from the Tropical Eastern Pacific and Grand Caribbean with descriptions of new species, Journal of Natural History 47 (17 - 18), pp. 1177-1242 : 1210-1212

Halosydna nesiotes (Chamberlin, 1919)

( Figure 16 )

Polynoe nesiotes Chamberlin, 1919b: 72–74 , plate 8, figure 8, plate 9, figures 1–5. Malmgrenia nesiotes: Hartman, 1938: 122 .

Halosydna nesiotes: Hanley, 1987: 160 ; Salazar-Silva, 2006: 148.

Type material

Holotype ( USNM 19460 ) of Polynoe nesiotes Chamberlin, 1919b , Isla Santa Margarita , Baja California Sur, Mexico, Albatross expedition 1891, id. R. V Chamberlin.

Description

Holotype in two fragments, not complete, anterior fragment with 14 segments, posterior fragment with 21 segments. Body dried, but the following features can be distinguished. Body with 18 pairs of elytrophores, seven on anterior fragment, 11 on posterior fragment, posteriormost segments with dorsal cirri. Elytra attached on anterior fragment absent on posterior fragment. Elytra without marginal papillae; surfaces granular due to numerous microtubercles ( Figure 16A ). The microtubercles conical-truncate, short, scattered over posterior half of surface ( Figure 16B ). Some elytra with tubercles hemispherical, large, sclerotized.

Notopodia shorter than neuropodia. Neuropodia distally truncate, small rounded lobe near acicula tip. Dorsal cirri and cirrophore dehydrated ( Figure 16C ). Anus dosal. Pygidium with anal cirri missing.

Notochaetae with rows of spines, the smaller curved, blunt tips, remaining ones slender tapering to capillary tips. Neurochaetae with rows of spines on upper region, tips bidentate, main tooth slightly curved, subdistal tooth shorter ( Figure 16D–F ).

Remarks

Although the holotype is dried, the parapodia, neurochaetae, number of elytra and segments agree with those of Halosydna as stated by Salazar-Silva (2006). Halosydna nesiotes is distinguished by having elytra without marginal papillae, but with microtubercles conical-truncate (abundant and short on posterior half) and longer hemispherical tubercles in some elytra. Chamberlin (1919b) decribed the species as having a “shrunken” prostomium (but prostomial appendages were not described), 34 segments and 15 pairs of elytra. However, it was described as having “granular appearance due to the presence of papillae and tubercles subconical, all of the same type excepting for variation in size, those toward the periphery of the papillose area becoming smaller”. The second pair were described as similar to the first, and those of median and posterior segments as almost smooth, with minute microtubercles. The elytra margins were not described, but were illustrated as smooth, which agrees with present observations.

Type locality

Santa Margarita Island, Baja California, Mexico.

Distribution

Baja California, Mexico (Santa Margarita Island).

Figures

Figure 16. Halosydna nesiotes (Chamberlin, 1919b). Holotype USNM 19460. (A) elytron from middle segment; (B) same, microtubercles; (C) parapodium, posterior view; (D) bidentate neurochaetae; (E, F) neurochaetae tips.