Pulvinomyzostomum messingi, Summers, Mindi M., Al-Hakim, Iin Inayat & Rouse, Greg W., 2014

Summers, Mindi M., Al-Hakim, Iin Inayat & Rouse, Greg W., 2014, Turbo-taxonomy: 21 new species of Myzostomida (Annelida), Zootaxa 3873 (4), pp. 301-344 : 326

Pulvinomyzostomum messingi n. sp. Summers & Rouse

Fig. 8 D–G

Holotype: SIO-BIC A3800 hologenophore (1 spm: 95% ethanol). Off southwest Oregon (42° 44' 28.104" N, 128° 5' 48.2994" W), 1650 m. Collected via the R/V Western Flyer using the ROV Doc Ricketts (Dive 82) on 4 September 2007 by Julio Harvey. Genbank (COI—KM014174).

Host. Gephyrocrinus messingi Roux & Lambert ( Hyocrinidae , Hyocrinida , Crinoidea). SIO-BIC E5662. Genbank (COI—KM014350).

Etymology. Named for Charles Messing, for whom its host crinoid is also named for, and in recognition for his often noticing and collecting myzostomids on crinoids.

Diagnosis and description. Holotype free-living ( Fig. 8 D). Body elongate. Length ~ 6 mm; width ~ 4 mm following fixation. Dorsal surface furrowed ( Fig. 8 E). Body margin acirrate ( Fig. 8 G). Mouth and cloaca subterminal on ventral surface, midway between first and last pairs of parapodia and body margin. Five pairs of parapodia. Color in life unknown, pale yellow following fixation.

Remarks. Unlike other members of Pulvinomyzostomum , where a large female remains stationary in the mouth, Pulvinomyzostomum messingi n. sp. was collected living free on the host. This is the first record of Pulvinomyzostomum on a stalked crinoid— Pulvinomyzostomum pulvinar and Pulvinomyzostomum messingi n. sp. were both found on antedonid hosts. Pulvinomyzostomum messingi n. sp. is also the first description of a myzostomid associated with a stalked crinoid in the east-Pacific and, with the exception of Stelechopus hyocrini Graff, 1884 , is the only known myzostomid from a hyocrinid. The other free-living myzostomids on stalked crinoids (currently in Eenymeenymyzostoma Summers & Rouse (2014) , Myzostoma Graff, 1884a , and Stelechopus Graff, 1884a ) are known from Japan, south of the Philippines, Antarctica , and the Caribbean ( Table 1). All but Stelechopus have noticeable marginal cirri, unlike Pulvinomyzostomum messingi n. sp.

Figures

FIGURE 8. (A – C) Live photographs of Pulvinomyzostomum inaki n. sp. — (A, B) female, (A) dorsal view showing raised ridges, (B) ventral view showing five pairs of parapodia, cirri on body margin, and small dwarf males, abbreviations: males (m); pharynx (p); (C) males, ventral and dorsal views showing extended smooth proboscis and scalloped margin. (D – G) Pulvinomyzostomum messingi n. sp. — (A) live photograph of host, Gephyrocrinus messingi with ophiuroid associate and possible myzostomids on arms, indicated with arrows; (E – G) photographs of fixed samples, (E – F) on host’s arms, dorsal view showing ridged surface (E), abbreviation: host pinnule (pi), (G) ventral view, showing acirrate body margin. Scalebars 30 cm (D); 1 mm (E – G); 0.5 mm (C); 0.2 mm (A, B).