Dermatobranchus leoni, 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 : 321-323

DERMATOBRANCHUS LEONI SP. NOV.

( FIGS 58C , 63 , 64 )

Dermatobranchus sp. 19 Gosliner, Behrens & Valdés, 2008: 314, above bottom photo.

Type material: Holotype: CASIZ 167453 , dissected, Ligpo Island , Balayan Bay, Luzon, Philippines, 42 m depth, collected iv.2003 by C. Petrinos.

Geographical distribution: Thus far, this species is known only from the Philippines ( Gosliner et al., 2008).

Etymology: This species was collected by our friend and colleague, Constantinos Petrinos. The specific name leoni honours his son, Leon.

External morphology: The body shape of the living animal ( Fig. 58C ) is elongate, but broad, slightly flattened, and narrows at the posterior end. The foot does not project beyond the distinct mantle margin. The dorsum has very low, longitudinal ridges and tubercles that give a lumpy appearance to the notum. The oral veil is large and expansive with slightly pointed corners. The well-separated, bulbous rhinophores are situated behind the oral veil. They have a series of longitudinal lamellae on the rounded club, which has a small rounded apex. The stalk does not narrow noticeably. There are noticeable marginal sacs along the mantle edge.

There are no hyponotal or branchial lamellae under the mantle margin. The genital opening is situated in the anterior quarter of the body. The anus is situated approximately half of the way to the posterior end of the body.

The ground colour of the dorsum is bright reddish orange with a series of black longitudinal lines along the margin of the ridges. The dorsal pigment is not evenly distributed. Each black line is flanked by longitudinal rows of opaque white spots. The foot is opaque white with a broad orange marginal band. A series of black, dashed lines are present on the dorsal surface of the foot and extend to the marginal band. The rhinophore stalk is white with darker bands of tan and the club is entirely tan. The rhinophores have a black rhinophoral club with opaque white lines along the lamellae. The rhinophoral apex is opaque white. The oral veil is opaque white with black lines and an orange anterior margin.

Buccal armature: The shape of the buccal mass is broad and highly muscular. The jaws are large and thickly cuticularized ( Fig. 63A ), with a thick masticatory margin. The masticatory margin is irregular, but no distinct denticles are evident ( Fig. 63B ). The radular formula ( CASIZ 167453) is 29 ¥ 40.1.1.1.40 ( Fig. 63C ). The rachidian teeth ( Fig. 63D, E ) are broad with a large, bluntly pointed central cusp that extends beyond the 23–25 denticles on either side. These denticles are present along most of the length of the tooth. Each rachidian tooth extends outward from a broad base that has two elongate extensions from the posterior margin. The first lateral tooth ( Fig. 63D, E ) is compact, hooked, and denticulate with a longer pointed central cusp with nine to ten smaller denticles. The next five to six lateral teeth are also large hooks with a large central cusp and 12–20 elongate, narrow denticles. The remaining middle and outer lateral teeth are hook-shaped, without denticles ( Fig. 63F, G ).

Reproductive system ( Fig. 64 ): The ampulla is thick and simply curved. It bifurcates into the large female gland mass via a short oviduct and into the vas deferens. The majority of the female gland mass is composed of the mucous gland, whereas the membrane and albumen glands are much smaller. The prostatic portion of the vas deferens is relatively wide and convoluted and widens further as it enters the bulbous penial sheath. Within the penial sheath, the narrow penis is highly convoluted and terminates in a slightly rounded apex. Adjacent to the penis is the wide curved vagina, which terminates in a relatively large, spherical bursa copulatrix.

Remarks: Dermatobranchus leoni is similar in appearance to D. semistriatus Baba, 1949 , but the notum of D. leoni is covered with red pigment and the oral veil has large thick black lines rather than small spots. Additionally, the border of the foot of D. leoni has a wide orange margin, whereas that of D. semistriatus does not have a distinctly pigmented border. The masticatory border of the jaws of D. leoni ( Fig. 63B ) is smooth, whereas that of D. semistriatus has several rows of denticles ( Baba, 1949: text fig. 87). The rachidian tooth of D. leoni has a longer cusp with denticles occurring almost all the way to the end of the cusp, whereas in D. semistriatus they are all basal. Dermatobranchus leoni has 40 rows of outer laterals whereas D. semistriatus has 50–60.

Dermatobranchus nigropunctatus Baba, 1949 , D. tongshanensis Lin, 1981 , and D. multistriatus Lin, 1981 also bear some external resemblance to D. leoni . The colour pattern of D. nigropunctatus is similar with black and white pigment, but this species has white lines with black spots whereas D. leoni has black lines with white spots. Dermatobranchus leoni has black rhinophores with white lines, whereas D. nigropunctatus has orange rhinophores. The colour of D. tongshanensis differs from that of D. leoni in several significant ways. The dorsal surface of D. tongshanensis is olive with scattered brown patches whereas D. leoni is predominantly reddish orange. The longitudinal lines of D. tongshanensis are white and black, whereas in D. leoni there are fine black lines and opaque white spots. The rhinophores of D. tongshanensis are blue with white lamellae whereas they are black with white lamellae in D. leoni . The sides of the body and dark oral veil of D. tongshanensis have small black spots whereas there are large black dashes in D. leoni . Dermatobranchus multistriatus lacks any black lines and has yellowish white ridges with small black spots on the oral veil and side of the body. It is difficult to compare the colour descriptions provided by Lin with the present species and the black and white plate of living animals sheds little additional light on the colour pattern of the animals. All four of these species have a jaw that lacks denticles. The most significant internal difference is in the shape of the radular teeth. In D. nigropunctatus , D. tongshanensis , and D. multistriatus , the inner lateral teeth are large with an elongate cusp. In contrast, D. leoni has a very short inner lateral tooth with a short cusp, more similar to that found in D. ornatus . Similarly, the other lateral teeth of D. leoni have a blunt cusp whereas the laterals of the other three species are acutely pointed. The reproductive system of the other three species was not described. On the basis of the colour differences noted and the very different shape of the radular teeth, we have decided it is more prudent to describe D. leoni as a new taxon until fresh material from China permits a more detailed comparison.

Figures

Figure 58. Living animals. A, Dermatobranchus kalyptos sp. nov., Lombok Island, Indonesia, photo by Pauline Fiene. B, Dermatobranchus kokonas sp. nov., CASIZ 075272, Bagabag Island, Papua New Guinea, photo by T. M. Gosliner. C, Dermatobranchus leoni sp. nov., CASIZ 167455, Mabini Luzon, Philippines, photo by Constantinos Petrinos. D, Dermatobranchus microphallus sp. nov., Flores, Indonesia, photo by Pauline Fiene. E, Dermatobranchus oculus sp. nov., Okinawa, Japan, photo by Bob Bolland. F, Dermatobranchus piperoides sp. nov., CASIZ 068708, Rempi Lagoon, Papua New Guinea, photo by T. M. Gosliner. G, Dermatobranchus phyllodes sp. nov., CASIZ 070451, Bagabag Island, Papua New Guinea, photo by T. M. Gosliner. H, Dermatobranchus phyllodes sp. nov., CASIZ 173351, Bohol, Philippines, photo by Marina Poddubetskaia.

Figure 63. Dermatobranchus leoni sp. nov. Buccal armature, CASIZ 167453, Mabini, Luzon, Philippines. A, jaws; B, masticatory margin; C, entire radula; D, E, central portion of radula; F, middle radular teeth; G, outer radular teeth.

Figure 64. Dermatobranchus leoni sp. nov. Reproductive system, CASIZ 167453, Mabini, Luzon, Philippines. A, reproductive system; B, detail of penial papilla. a, ampulla; bc, bursa copulatrix; fg, female gland mass; p, penis; pr, prostate; ps, penial sheath; v, vagina; vd, vaginal duct. Scale bar = 0.66 mm.