Phyllidia alyta Yonow, 1996

Yonow, Nathalie, 2012, Opisthobranchs from the western Indian Ocean, with descriptions of two new species and ten new records (Mollusca, Gastropoda), ZooKeys 197, pp. 1-130 : 44-45

Phyllidia alyta Yonow, 1996 Fig. 17Plate 61

Phyllidia alyta Yonow, 1996: 500, fig. 9A-G, tab. 2 (Maldives, Mauritius); Apte 2009: 171, fig. 2t (Laccadive Islands); Yogesh Kumar et al. 2011: 111, fig. 3a (India).

Phyllidia elegans . - Eliot 1906: 562 (Maldives) (non Phyllidia elegans Bergh).

Material.

Maldives: 25 mm in length, Dhigu Tila, near Gulhi, South Malé Atoll, 12 m depth, 14 October 1994, leg. SG Buttress & RC Anderson; 28 × 12 mm, Bathala Island, Ari Atoll, 6 m depth, 28 July 1995, leg. SG Buttress & RC Anderson; 15 × 7 mm pres. ("light grey with black lines, rhinophores and last tubercle yellow"), Bathala Island, Ari Atoll, 10 m depth, 27 July 1995, leg. SG Buttress & RC Anderson; photographs of many individuals, 25-40 mm, March 1997, March 1998, March 1999, J Hinterkircher. - Sri Lanka: photos of two individuals, Negombo, N of Colombo, April 1995, RC Anderson; photos of one individual, Unawatuna, S of Galle, 27 December 2010, S Kahlbrock.

Description.

The preserved 15 mm juvenile is in perfect condition and easily recognised as Phyllidia alyta . Broken black line present on sole of foot despite its small size (Fig. 17A), but only two of the four longitudinal dorsal black lines are complete (Plate 61). Three rows of tubercles on midline between start of two lines: central row of tubercles joined by low ridge and only the last tubercle orange. Black crossbar between rhinophores lacking. Two larger specimens typical, with four dorsal black lines, black bar between rhinophores, and ventral broken black line. Foot thickened and concave anteriorly, and triangular tentacles bear groove along each outer side (Fig. 17B). Hyponotum hatched with spicules, dorsal black pigment showing through.

Distribution.

It is probable that the species described by Eliot (1906) is Phyllidia alyta : he distinguishes it from Phyllidia varicosa (he had specimens of both), and Phyllidia alyta is the only other species in the Indian Ocean with linearly-arranged orange tubercles and black lines dorsally in combination with a black line on the sole of the foot. This species appears to be restricted to the western Indian Ocean; there are only two internet records from south western Thailand on NudiPixel.