Dermatobranchus rodmani, Gosliner & Fahey, 2011

Gosliner, Terrence M. & Fahey, Shireen J., 2011, Previously undocumented diversity and abundance of cryptic species: a phylogenetic analysis of Indo-Pacific Arminidae Rafinesque, 1814 (Mollusca: Nudibranchia) with descriptions of 20 new species of Dermatobranchus, Zoological Journal of the Linnean Society 161 (2), pp. 245-356 : 332-335

DERMATOBRANCHUS RODMANI SP. NOV.

( FIGS 74A, B , 75–77 )

Dermatobranchus sp. 16 Gosliner, Behrens & Valdés, 2008: 313, bottom photo.

Type material: Holotype: CASIZ 173400 , dissected, west of Nosy Valiha , Radama Islands, Madagascar, collected 20.x.2005 by T. Gosliner . Paratypes: CASIZ 174170 , one specimen, dissected, Pulau Labus , Tioman, eastern Malaysia, 10 m depth, collected 2.x.2007 by D. W. Behrens . CASIZ 178238 , piece of 174170 taken for DNA examination, Pulau Labus , Tioman, eastern Malaysia, 10 m depth, collected 2.x.2007 by D. W. Behrens . CASIZ 069745 , one specimen, dissected, reef north of Pig Island , Madang, Papua New Guinea, 24 m depth, collected 24.viii.1989 by T. Gosliner . CASIZ 173425 , one specimen, west of Nosy Kalakajoro , Radama Islands, Madagascar (13°58.37′S, 47°41.76′E), 15–17 m depth, collected 17.x.2005 by S. Fahey .

Geographical distribution: This species is known from the north-west coast of Madagascar to eastern Malaysia and Papua New Guinea (present study).

Etymology: The specific name rodmani is in honour of James Rodman, long-time Program Officer of the Division of Environmental Biology of the National Science Foundation, who had the vision and determination to realise the creation of several programmes that have fostered the resurgence of systematic biology in the United States. The Partnerships for Enhancing Expertise in Taxonomy programme that was his brain-child has been critical in providing support for training the next generation of opisthobranch mollusc systematists.

External morphology: The body shape of the living animal ( Fig. 75A, B ) is elongate and triangular, flattened, and narrows at the posterior end. The foot projects only slightly beyond the distinct mantle margin. The notum is smooth and fleshy. There are three low, distinct longitudinal ridges in the larger specimen from Malaysia and no ridges are evident in the material from Madagascar. The oral veil extends forward and has rounded corners. The widely spaced, club-shaped rhinophores are situated behind the oral veil. They have a series of longitudinal lamellae on the rounded club. The stalk does not narrow noticeably. Marginal sacs are visible along the mantle edge and each contains elongate, stiff rodlets ( Fig. 75A ). There are no branchial or hyponotal lamellae. The genital opening is on the right side of the body, near the anterior quarter of the body. The anus is situated approximately one - third of the way to the posterior end of the body.

The ground colour of the notum, the oral veil, and the foot is pale pinkish white to tan. One or two transverse brown patches are present near the anterior and posterior thirds of the body. The notum and oral veil have a yellowish margin, which may contain fine punctations of brown. The rhinophores, including the base, lamellae, and apex, are brown with a few opaque white spots on their surface.

Buccal armature: The jaws ( Figs 75B , 76A ) are elongate with one to two rows of denticles with highly divided apices ( Figs 75C , 76B ) along the lower third of the jaw. The radula is elongate and narrow ( Fig. 75D ). The radular formula of the holotype ( CASIZ 173400) is 24 ¥ 2.1.1.1.2 and that of one paratype ( CASIZ 174170) is 40 ¥ 5–6.1.1.1.5–6. The rachidian teeth ( Figs 75E, F , 76C ) are broad with a broad base and an elongate, wide central cusp. The cusp is flanked by six to nine elongate denticles on either side. The inner lateral tooth is extremely broad with 7–15 elongate denticles on the outer side of the central cusp. The next zero to three laterals bear 10–13 denticles on the outer side of the sharp cusp. The outer two to three teeth lack denticles ( Figs 75E, F , 76D ).

Reproductive system: The reproductive organs are androdiaulic ( Fig. 77 ). The ampulla is curved and saccate, with a short-branched oviduct connecting to the female gland mass and a second branch becoming the thin, convoluted vas deferens that terminates in an elongate, curved conical penial papilla. The papilla has an acutely pointed apex. The well-developed female gland mass is well differentiated into a large mucous gland and smaller albumen and membrane glands. Adjacent to the penis is a thin, straight vagina that leads to a relatively small spherical or pyriform bursa copulatrix inside the folds of the female glands.

Remarks: Dermatobranchus rodmani is externally similar to other species with brownish bands or horizontal blotches including D. fasciatus , D. semilunus , and D. tuberculatus . Of these species, it differs from D. fasciatus and D. semilunus in lacking numerous prominent longitudinal ridges. Dermatobranchus tuberculatus has elevated tubercles on the notum that are not present in D. rodmani . The radula of D. rodmani differs from all of these species in that it is thin and elongate with relatively few teeth and with a broad inner lateral tooth with numerous denticles.

The radula is similar in shape and dentition to D. substriatus D. striatellus , D. fortunatus , D. earlei , D. funiculus , D. microphallus , D. piperoides , and D. kokonas . Of these species, D. substriatus , D. striatellus , D. earlei , and D. funiculus all have prominent dorsal ridges that are not evident in the other species. Both D. rodmani and D. microphallus have relatively low ridges on the notum whereas the remaining species entirely lack ridges. The body of D. microphallus is black with faint white longitudinal lines along the low ridges. In contrast, D. rodmani is pale pink to tan with brown patches on the notum. The radular formula of D. microphallus is 31 ¥ 9.1.1.1.9 whereas it is 24 ¥ 2.1.1.1.2 and 40 ¥ 5–6.1.1.1.5– 6 in D. rodmani . The inner seven teeth of D. microphallus ( Fig. 65 ) are denticulate whereas in D. rodmani ( Figs 75–76 ) only the inner one to four teeth are denticulate. In D. microphallus ( Fig. 66 ) the small penial sheath is at the distal end of a long prostatic section whereas in D. rodmani ( Fig. 77 ), the short prostate leads to a much longer penial papilla and sheath.

Figures

Figure 65. Dermatobranchus microphallus sp. nov. Buccal armature, CASIZ 086655, Flores, Indonesia. A, jaw; B, masticatory margin; C, central portion of the radula; D, middle lateral teeth; E, half-row of radular teeth; F, outer lateral teeth.

Figure 66. Dermatobranchus microphallus sp. nov. Reproductive system CASIZ 086655, Flores, Indonesia. a, ampulla; bc, bursa copulatrix; pr, prostate; ps, penial sheath; v, vagina; vd, vaginal duct. Scale bar = 0.33 mm.

Figure 74. Living animals. A, Dermatobranchus rodmani sp. nov., CASIZ 173400, Radama Islands, Madagascar, photo by T. M. Gosliner. B, Dermatobranchus rodmani sp. nov., CASIZ 174170, Pulau Labus, Malaysia, photo by D. W. Behrens. C, Dermatobranchus semilunus sp. nov., Pulau Chimbe, off Tioman, Malaysia, photo by T. M. Gosliner. D, Dermatobranchus semilunus sp. nov., CASIZ 073045, Madang, Papua New Guinea, photo by T. M. Gosliner. E, Dermatobranchus semilunus sp. nov., CASIZ 110407, Cabilao, Bohol, Philippines, photo by T. M. Gosliner. F, Dermatobranchus tuberculatus sp. nov., CASIZ 110361, Ligpo Island, Luzon, Philippines, photo by T. M. Gosliner. G, Dermatobranchus tuberculatus sp. nov., CASIZ 096332, Devil’s Point, Maricaban Island, Luzon, Philippines, photo by T. M. Gosliner. H, Dermatobranchus tuberculatus sp. nov., CASIZ 174171, Pulau Tenggol, Malaysia, photo by T. M. Gosliner.

Figure 75. Dermatobranchus rodmani sp. nov. Buccal armature, CASIZ 173400, Radama Islands, Madagascar. A, defensive rodlets; B, jaws; C, masticatory margin; D, entire radula; E, F, central portion of radula.

Figure 76. Dermatobranchus rodmani sp. nov. Buccal armature, CASIZ 174170, Pulau Labus. Tioman, Malaysia. A, jaws; B, masticatory margin; C, central portion of radula; D, outer radular teeth.

Figure 77. Dermatobranchus rodmani sp. nov. Reproductive system, CASIZ 173400, Radama Islands, Madagascar. a, ampulla; bc, bursa copulatrix; fg, female gland mass; p, penis; pr, prostate; v, vagina; vd, vaginal duct. Scale bar = 0.37 mm.