Dermatobranchus microphallus, 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 : 323-325

publication ID	https://doi.org/ 10.1111/j.1096-3642.2010.00649.x
persistent identifier	https://treatment.plazi.org/id/761B2D60-4838-E201-0952-FBAEFB1D3D39
treatment provided by	Valdenar
scientific name	Dermatobranchus microphallus
status	sp. nov.

Treatment

DERMATOBRANCHUS MICROPHALLUS View in CoL SP. NOV.

( FIGS 58D View Figure 58 , 65 View Figure 65 , 66 View Figure 66 )

Type material: Holotype: CASIZ 086655 , one specimen, dissected, 8 mm preserved, dissected, Unjuran Reef , Flores, Indonesia, 1 m depth, collected 29.iv.1992 by P. Fiene.

Geographical distribution: This species is known only from Flores, Indonesia (present study).

Etymology: The specific name microphallus refers to the small size of the fully mature penis of this species.

External morphology: The body shape of the living animal ( Fig. 58D View Figure 58 ) is narrow and elongate, flattened, and narrows at the posterior end. The wide foot does not project beyond the distinct mantle margin. There is a series of low longitudinal dorsal ridges running the length of the body. The oral veil extends forward and is rounded at the corners. The rhinophores are situated behind the oral veil. They have a series of longitudinal lamellae on the rounded club. The stalk narrows noticeably. There are no lamellae on the stalk. Marginal sacs are readily visible along the mantle edge and are smaller and more numerous than in most other species observed. There are no branchial or hyponotal lamellae. The genital opening is situated approximately one-quarter of the way along the body side and the anus is situated about halfway along the body side.

The ground colour of the notum is black with about eight fine, opaque white longitudinal lines that are isolated on either side of the midline of the notum. Many of these also have larger opaque white spots along their length, especially on the lateral portions copulatrix is slightly smaller than the ampulla and larger than the penial sheath. From the bursa, the long, narrow vaginal duct extends into the narrow vagina, which exits into the genital atrium, adjacent to the penis. The specimen was determined to be fully mature by the presence of large fully developed female reproductive glands.

of the notum. The entire notal margin is opaque white. The rhinophore stalk is the same black colour as the notum as is the club, which has opaque white lines. The oral veil is opaque white throughout.

Buccal armature: The jaws are ovoid in shape and are thinly cuticularized ( Fig. 65A View Figure 65 ), with a thin masticatory margin and one to two rows of rounded denticles, some of which have irregular apices ( Fig. 65B View Figure 65 ). The radula is long and narrow with a formula of 31 ¥ 9.1.1.1. 9 in the holotype (CASIZ 086655). The rachidian teeth ( Fig. 65C, E View Figure 65 ) are broad with large lateral cusps at the base of each tooth. There is a wide, pointed central cusp that is longer than the nine to ten long, flanking denticles on each side. The inner lateral teeth ( Fig. 65D View Figure 65 ) are broad with a pointed first denticle that is longer than the following nine to ten long, narrow pointed denticles. The next eight lateral teeth ( Fig. 65D–F View Figure 65 ) are elongate hooks with three to ten denticles, the number decreasing on the teeth furthest from the rachidian. The outermost teeth ( Fig. 65F View Figure 65 ) have a single denticle adjacent to the elongate cusp.

Reproductive system: The reproductive organ arrangement is androdiaulic. The hermaphroditic duct is long and narrow and leads into the elongate, rounded, saccate ampulla ( Fig. 66 View Figure 66 ). The ampulla bifurcates near the centre of the female gland mass into the short oviduct and the long, tubular prostate, which coils once. The prostate expands into the small, conical, muscular penial papilla. The pyriform bursa Remarks: This species is immediately recognizable by its narrow elongate body with black pigment and fine white longitudinal lines. It is similar in colour to many species of Armina and to D. albineus and D. arminus , but has a much darker body colour. Internally, its radula is much narrower than any of these species but is most similar to D. albineus . This species also has broad rachidian tooth and a broad inner lateral. The most significant difference is the greater number of lateral radular teeth per row (12–18) in D. albineus ( Fig. 31 View Figure 31 ) than in D. microphallus (ten) ( Fig. 65 View Figure 65 ). Additionally, the eight to ten outer lateral teeth of D. albineus lack any denticles, whereas all of the teeth of D. microphallus have at least one denticle. The reproductive system of these two species differs markedly. In D. albineus ( Fig. 32 View Figure 32 ) the penial sheath is wide and elongate, whereas in D. microphallus ( Fig. 66 View Figure 66 ) it is small and conical. Additionally, D. albineus has a wide vaginal base whereas it is narrow in D. microphallus .

Dermatobranchus microphallus is also similar in internal morphology to several other members that are characterized by having a long narrow radula with broad, denticulate inner lateral teeth: D. substriatus D. striatellus , D. fortunatus , D. earlei , D. funiculus , D. rodmani , D. piperoides , and D. kokonas . The black colour with white lines is unique to D. microphallus . Of these species only D. rodmani may have low ridges on the notum in larger individuals. The other species either entirely lack ridges ( D. fortunatus , D. piperoides , D. kokonas ) or have more prominent ridges ( D. substriatus D. striatellus , D. fortunatus , D. earlei , D. funiculus ). Dermatobranchus rodmani ( Figs 75F View Figure 75 , 76D View Figure 76 ) differs from D. microphallus by its light, mottled body colour, the presence of fewer dorsal ridges (maximum of three), and by its outer two lateral teeth devoid of denticles.