Myzostoma susanae, 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 : 319-321

Myzostoma susanae n. sp. Summers & Rouse

Fig. 6 J–M

Myzostoma coriaceum ( Fig. 1 A; DNA from other specimen)— Lanterbecq et al. (2006)

Holotype: SAM E3879 hologenophore (1 spm: ½—in 70% ethanol after formalin fixation; ½—95% ethanol). Mermaid Cove, Lizard Island Reef, Australia (14°38’51.1” S, 145°27’9.6” E), 6 m. Collected using scuba on 18 November 2001 by GWR. Genbank (COI—KM014200).

Host. Comaster schlegelii (Carpenter) ( Comatulidae , Comatulida , Crinoidea). SAM K2025. Genbank (28S—KM491766).

Etymology. Named for Susan Rouse, mother of GWR, in honor of her birthday.

Diagnosis and description. Holotype body circular, ~ 5 mm in diameter following fixation. Body margin with 20 very small, thin cirri ( Fig. 6 J–M). Mouth and cloaca on ventral surface, in line with first and last pair of parapodia respectively. Five pairs of parapodia. Lateral organs closer to parapodia than body margin ( Fig. 6 L). Live and preserved color bright white.

Remarks. There are five other species with short marginal cirri recorded from feather stars, all of which are large in size (> 3 mm) ( Table 1). Myzostoma seymourcollegiorum Rouse & Grygier, 2005 has low parapodial cirri and thicker marginal cirri and is also clearly different from DNA sequence data, though it is closely related to M. susanae n. sp. ( Summers & Rouse 2014). Myzostoma seymourcollegiorum is found in southern Australia, associated with Cenolia trichoptera (Müller) and possibly Cenolia glebosus Rowe et al. ( Rouse & Grygier 2005) , though the latter association has yet to be assessed with DNA sequencing. The other four species with short marginal cirri were all described by Graff and his descriptions were all brief. Myzostoma brevicirrum Graff, 1884a was described from Tonga (31 m depth), collected with Clarkcomanthus comanthipinnus (Gislén) . Specimens were up to 5 mm in diameter, transparent yellow-ish in color (one specimen was brown), and with a proboscis with papillae. Myzostoma pallidum Graff, 1877 and Myzostoma triste Graff, 1877 were described from Bohol, Philippines. Myzostoma pallidum was found on three species of crinoids— Comatula solaris and Comanthus parvicirrus (hosts revised in Graff, 1884a). Specimens were ~ 3 mm in diameter and pale grey-brown with a dirtyyellow edge, the drawing showing a proboscis with papillae. Myzostoma triste was recorded from Comanthus parvicirrus (in Graff, 1884a). Material was around 4.5 mm long and 4 mm wide and dark brown in color. Myzostoma coriacium Graff 1884a was described from Port Denison, Australia associated with Colobometra perspinosa (though host identification seems dubious). The diameter of the three specimens were between 2.7 to 9 mm, with the margins bent downwards. The specimens were darkish brown in color. The lateral organs described as located midway between the parapodia and body margin (though the drawing shows them closer to the parapodia). Myzostoma susanae n. sp. is distinguishable from all of these species based on color and host.

Figures

FIGURE 1. Live photographs of Asteromyzostomum grygieri n. sp. (A, B) Holotype (SIO-BIC A 3801) and other non-types on host Labidiaster annulatus, arrowheads indicate myzostomids. (C, D) Paratype (SIO-BIC A 3554) ventral, mouth pierced through body wall (C) and dissected (D), arrow shows mouth and ring of circumoral tentacles. (E) Paratype (SIO-BIC A 3232) ventral, five parapodia visible to left of mouth, indicated with roman numerals. (F) Two juveniles (non-types), ventral, showing five pairs of parapodia to left and right of mouth; one side indicated with roman numerals, the third pair offset from the others. Scalebars 1 cm (A); 1 mm (C – F).

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).