TRAPANIA DARVELLI RUDMAN, 1987

(FIGS 4G, 10)

Trapania darvelli Rudman, 1987: 206−209, figs 12A, 15; Rudman & Darvell, 1990; Ono, 2004: 97, middle photograph; Debelius & Kuiter, 2007: 19, middletop photograph; Gosliner et al. 2008: 138, second photograph from the top; Humann & Loach, 2010: 307, middle-right photograph; Gosliner et al., 2015: 141, bottom-right photograph; Gosliner et al., 2018: 59, bottom-left photograph.

Material examined: CASIZ 186129, one specimen, sequenced, Devil’s Point (13.65084°N 120.84145°E), Maricaban Island, Batangas Province, Philippines, 07 May 2011, collected by Peri Paleracio. CASIZ 197303, one specimen, sequenced, Verde Island Passage (13.91000°N 120.60000°E), Calatagan, Batangas Province, Luzon Island, Philippines, 16 May 2014, collected by Shayle Matsuda. CASIZ 202112, one specimen, sequenced, Verde Island Passage (13.91422°N 120.60643°E), Calatagan, Batangas Province, Luzon Island, Philippines, 09 May 2013 , collected by T. M. Gosliner . CASIZ 222004, one specimen, dissected and sequenced, Balayan

294 D. S. SMIRNOFF ET AL.

Bay (13.72000°N 120.87000°E), Mabini (Calumpan Peninsula), Batangas Province, Luzon Island, Philippines, 5–17 m depth, 28 March 2017, collected by William Mendoza.

Geographical distribution: Known from the Western Pacific Ocean, including Hong Kong, the Philippines, the Solomon Islands, Vanuatu and the Ryukyu Islands, Japan (Rudman, 1987; Ono, 2004; Gosliner et al. 2008, 2015, 2018; Humann & DeLoach, 2010; present study).

Description: The external morphology, jaws and radula have been previously well described (Rudman, 1987). We add an additional description of the buccal apparatus and the first description of the reproductive system.

Buccal mass: The buccal mass is thick and muscular with a slightly elevated buccal pump. The jaws are well developed and contain several rows of curved, hook-shaped denticles (Fig. 10A).

The radular formula is 32 × 1.0.1 (Fig. 10B). The older teeth (Fig. 9C) are markedly smaller than the newer ones and the radula widens gradually towards the more newly developed teeth (Fig. 10D). All of the teeth are slightly curved and narrow at the inner base and broaden out at the outer edges. The teeth bear numerous denticles on the inner side of the primary cusp that are similar but increase in length slightly nearer the primary cusp. There are approximately five to nine denticles on the inner side of the much larger primary cusp in the older teeth, and one short, triangular denticle on the outer side of the cusp. The newer teeth have 12–18 denticles on the inner side of the fairly broad primary cusp and there does not appear to be an outer denticle.

Reproductive system: The mature reproductive system is triaulic (Fig. 4G). The narrow pre-ampullary duct enters the elongate, saccate ampulla at the proximal end of the ampulla. The ampulla is widest proximally and narrows again at the post-ampullary duct and divides into the short, narrow oviduct, which enters the female gland mass, and the vas deferens. The vas deferens gradually widens into the thick prostatic portion that loops prior to expanding distally, immediately before it narrows abruptly into the long, narrow ejaculatory segment. The ejaculatory segment widens into a short penial sac. The penial sac terminates adjacent to the vagina. The width of the vagina remains uniformly narrow along a long length until it enters the base of the large, spherical bursa copulatrix adjacent to the receptaculum duct. The long receptaculum duct enters the base of the smaller, smaller pyriform receptaculum seminis. The moderately long uterine duct emerges from the receptaculum duct near the base of the receptaculum and enters the female gland mass. The female gland mass is composed of the large mucous gland and the smaller albumen and membrane glands.