Myzostoma tertiusi, 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 : 321

Myzostoma tertiusi n. sp. Summers, Al-Hakim & Rouse

Fig. 6 N–P

Holotype: MZB Pol. 0 0 131 hologenophore (1 spm: ½—in 70% ethanol after formalin fixation; ½—95% ethanol). Otdima Reef, Raja Ampat, Indonesia (0°32'59.70"S, 130°37'10.88"E), less than 20 m. Collected using scuba on 22 October 2013 by MMS, GWR, and Tertius Kammeyer. Genbank (COI—KM491763).

Host. Colobometra perspinosa (Carpenter) ( Colobometridae , Comatulida , Crinoidea). SIO-BIC E6157. Genbank (COI—KM491786).

Paratypes: SIO-BIC A3703 (2 spms: 1—in 70% ethanol after formalin fixation; 1—95% ethanol). Outside of Tab Island, Madang, Papua New Guinea (5° 10.013'S, 145° 50.455'E), 5– 20 m. Collected using scuba on 7 December 2012 by MMS and GWR. Genbank (COI—KM014206). Host: Cenometra bella (Hartlaub) . MNHN-IE- 2013-8070 (dried voucher) & SIO-BIC E5939 (tissue subsample in 95% ethanol). Genbank (COI—KM491787).

Etymology. Named for Tertius Kammeyer, an avid myzostomid hunter who found the holotype with MMS and GWR.

Diagnosis and description. Holotype body circular, ~ 4 mm in diameter following fixation. Body margin scalloped from many unequal-sized triangular cirri ( Fig. 6 N–P). White dorsal longitudinal ridge ( Fig. 6 N– O). Mouth and cloaca subterminal, in line with parapodia. Extended proboscis smooth. Five pairs of parapodia, twothirds of the way to body margin ( Fig. 6 P).

Remarks. The body shape of Myzostoma tertiusi n. sp. is not entirely circular, the scalloped margin resembling that of M. pipkini n. sp. One circular myzostomid species has been described from the same host, Colobometra perspinosa . This species, Myzostoma coriaceum Graff, 1884a is circular, over 9 mm in diameter and most similar in form to specimens found on Comatulidae (see remarks for M. susanae n. sp.). The host identification for this specimen is dubious and it is easily differentiated from Myzostoma tertiusi n. sp. Many species associated with Mariametroidea have a scalloped margin, particularly the elongated forms of Hypomyzostoma . Of these, only M. attenuatum Grygier, 1989 and Myzostoma pipkini n. sp. and have been reported from Colobometra perspinosa and Cenometra bella , both of which differ morphologically and in molecular data ( Summers & Rouse 2014) from M. tertiusi n. sp.

Figures

FIGURE 6. (A – I) Myzostoma pipkini n. sp. — (A – E) SEM of paratype (SIO-BIC A 3818), (A – B) dorsal, showing transverse ridges and scalloped margin, (C) ventral showing smooth extended proboscis, five pairs of parapodia restricted to anterior twothirds of body, and position of cloaca midway between last pair of parapodia and body margin, (D) hook within parapodia, (E) two parapodia with small cirrus buds, indicated by arrow head; (F – I) live photographs, (F – G) paratype SIO-BIC A 3746, dorsal view on host Colobometra perspinosa (F) and separated, showing transverse ridges and scalloped margin (G), (H – I) paratype (SIO-BIC A 3755), (H) dorsal view, (I) ventral, showing smooth proboscis, restricted parapodia, and position of cloaca. (J – M) Live photographs of Myzostoma susanae n. sp. holotype (SIO-BIC A 3803), (J, M) on host, Comaster schlegelii, (K) dorsal view, a few small cirri visible on body margin, (L) ventral view showing five pairs of parapodia, indicated with an arrow head, and alternating lateral organs, anus (a) and pharynx (ph). (N – P) Live photographs of Myzostoma tertiusi n. sp. holotype (SIO- BIC A 3793) — (N) on host, Colobometra perspinosa, (O) dorsal view showing color pattern and scalloped margin, (P) ventral view showing five pairs of parapodia and smooth extended proboscis. Scalebars 2 mm (J-M); 1 mm (N – P); 0.5 mm (A – C, F – I); 200 Μm (E); 20 Μm (D).