Hoplodoris rosans, Donohoo & Gosliner, 2020

Donohoo, Samantha A. & Gosliner, Terrence M., 2020, A tale of two genera: the revival of Hoplodoris (Nudibranchia: Discodorididae) with the description of new species of Hoplodoris and Asteronotus, Zootaxa 4890 (1), pp. 1-37 : 19-22

Hoplodoris rosans sp. nov.

( Figs. 7 C–D, 8C–D, 10C, 11E–F, 13)

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Otinodoris sp. 1— Gosliner et al. 2008: page 174, second photograph from the bottom. Gosliner et al. 2015: page 182, middle right photograph. Gosliner et al. 2018: page 103, top left photograph.

Type material. Holotype: CASIZ 182921 , one specimen, dissected, foot subsampled for molecular analyses, Basura , 13.65648° N 120.91869° E, Mabini (Calumpan Peninsula), Batangas Province, Luzon Island, Philippines, May 2010, Mike Miller . Paratypes: CASIZ 182837 , one specimen, foot subsampled for molecular analyses, Arthur’s Rock, 13.70775° N 120.87481° E, Maricaban Strait , Mabini (Calumpan Peninsula), Batangas Province, Luzon Island, Philippines, 14.6m depth, 20 May 2010 , Alicia Hermosillo. CASIZ 105692 , one specimen. North Side of Mindoro Island , 13.52657° N 120.95817° E, Philippines, 28 February 1995 , T.M. Gosliner.

Type locality. Basura , Mabini (Calumpan Peninsula), Batangas Province, Luzon, Philippines .

External morphology. The living animals ( Figs. 7 C–D) are large, oval in shape, range in length between 80–120 mm, and are found along reef slops between 12–15m, where they are nocturnally active. The body color is cream and tan with brown papillae with short random branches along a single stem; numerous large tubercles ( Figs. 8 C–D); pink, red, and light purple concavities along the center; tan and cream concavities in descending size (medium–small) approaching the edge of the mantle; with some concavities lined with black rings, and small purple blotches along the mantle rim. The underside of the mantle is cream with medium rose-colored spots along the edge, large rose-colored blotches surrounding the foot and a light purple band around the mantle’s edge. The gill consists of six pale violet tripinnate branchial leaves, light brown rachises with scattered opaque white spots, and surround the anus. The gill pocket contains six distinct lobes with a ring of light pink spots around the edge and patterning like the rest of the body. The rhinophores are perfoliate with 30–45 reddish lamellae. The base and middle regions are brown with some opaque white spots towards the middle region, lower lamellae, and apex. The two rhinophoral sheaths are lightly crenulated with similar body coloration. The foot is broad and reddish purple in color with a tan line along the edge and notched anteriorly. A flat, slightly rounded triangular oral tentacle is present laterally on either side of the labial region and mouth.

Internal anatomy. Buccal mass and radula. The buccal mass is muscular and anteriorly connects to a thin labial cuticle which has reduced jaw rodlets ( Fig. 13A ). The radula is composed of predominantly smooth hamate teeth and the radular formula is 42 × 116.0. 116 in the holotype CASIZ 182921. The inner lateral teeth ( Fig. 13B ) are short with a broad base and a strongly curved cusp. The first 21 inner teeth have one to four triangular denticles along the outer side of the cusp. The middle lateral teeth ( Fig. 13C ) are slightly larger and more elongate with a narrow cusp and no denticles. The outer lateral teeth ( Fig. 13D ) also lack denticles but are larger and more elongate than the middle lateral teeth with a slightly rounder smooth cusp.

Reproductive system. An elongate, convoluted ampulla expands and loops before narrowing into the vas deferens and a short oviduct ( Fig. 10C ). The vas deferens expands and enters a large, spherical prostate that quickly narrows distally into a long convoluted ejaculatory portion. The ejaculatory portion widens again before expanding into a muscular, penial bulb that enters the common genital atrium shared with the vagina and accessory gland. The penis is armed with numerous penial spines ( Fig. 11E ), which have a broad base and are slightly curved at the tip. The broad short vagina narrows as it enters the large, spherical bursa copulatrix.A short, duct connects near the base of the bursa to a smaller, ovoid receptaculum seminis. The uterine duct also connects to the base of the receptaculum and enters the female gland mass. A massive nodular accessory gland is connected by a long and convoluted duct that expands into a muscular base that opens into the center of the common genital atrium between the vagina and the penis. Within the base of the accessory gland there is a large, rose-thorn shaped accessory spine with a broad base and a strongly curved narrow cusp ( Fig. 11F ).

Etymology. This species is named Hoplodoris rosans after the large rose-colored spots along the underside of the mantle; as well as for the large, rose-thorn shaped accessory spine.

Geographical distribution. The Verde Island Passage of the Philippines.

Remarks. Our molecular phylogeny, the ABGD analysis, and the bPTP analysis show that H. rosans is a distinct species within Hoplodoris and has a minimum divergence of 15.99% with the type species H. desmoparypha . Externally, the body coloration of H. rosans is a cream and tan color with large tubercles, colorful concavities ranging from pink to purple, and brown papillae; whereas, H. balbon is tan in coloration with reddish-brown compound papillae and light brown tubercles and H. desmoparypha is cream or white in color with numerous large brown to dark brown blotches, large light brown and reddish-brown tubercles, and scattered light brown compound papillae. The jaw rodlets in H. rosans are vastly different than the rodlets in either H. balbon or H. desmoparypha . The rodlets found in H. rosans are greatly reduced; whereas, the rodlets are semi-elongate in H. desmoparypha and extremely elongate in H. balbon with rounded or irregular tips. The radular teeth in H. rosans . H. balbon , and H. desmoparypha are similar in shape and size; however, the consistency of denticles and the shape of the outermost tooth vary between the species. In H. rosans all of the first 21 inner teeth have denticles which may vary in number, while in H. balbon and H. desmoparypha only some of the inner teeth have denticles. Hoplodoris rosans and H. balbon have no denticles along the middle or outer lateral teeth; however, denticles are present along those teeth in H. desmoparypha . The shape of the outermost tooth in H. rosans is a reduced version of the rest of the outer lateral teeth; whereas in H. balbon and H. desmoparypha the outermost tooth is reduced and semi-fimbriate (Bergh 1880, plate F, fig. 4).

The reproductive system of H. rosans has a large rounded prostate armed with slightly curved penial spines, a slightly smaller bursa copulatrix, and a small receptaculum seminis, while H. balbon also has a large prostate armed with stalked rather than sessile conical penial spines, but a smaller irregular shaped bursa copulatrix, and a much smaller receptaculum seminis. Similarly, H. desmoparypha also has sessile conical penial spines and a small receptaculum seminis, but the prostate is more irregular in shape and the rounded bursa copulatrix is much larger in size (Bergh 1880, plate F, fig. 5; Dayrat 2010, fig. 200B). The size and shape of the accessory gland and accessory spine also varies. In H. rosans the accessory gland is much larger, irregularly shaped and has a large, rose thorn shaped accessory spine at the base, while H. balbon has a slightly smaller, elongate accessory gland with a smaller lightly curved accessory spine and H. desmoparypha has a slightly larger, more irregularly shaped accessory gland with a broader, curved accessory spine (Bergh 1880, plate F, figs. 5, 12‾14; Dayrat 2010, fig. 203B).

Figures

FIGURE 7. Hoplodoris, living specimens. A. Hoplodoris desmoparypha CASIZ 309550, Palau; B. Hoplodoris balbon sp. nov. CASIZ 171406, Philippines; C. Hoplodoris rosans sp. nov. CASIZ 182837, Philippines, dorsal view; D. Hoplodoris rosans sp. nov. CASIZ 182837, Philippines, ventral view. Photos: (A, by Coral Reef Research Foundation), (B, by Marina Poddubetskaia), and (C–D, by Terry Gosliner).

FIGURE 8. Hoplodoris. Tubercles and papillae, scanning electron micrographs. A. Hoplodoris desmoparypha CASIZ 309550; B. Hoplodoris balbon sp. nov. CASIZ 171406. C–D. Hoplodoris rosans sp. nov. CASIZ 182921.

FIGURE 10. Hoplodoris, reproductive system. A. Hoplodoris desmoparypha CASIZ 309550, (scale bar = 0.5mm); B. Hoplodoris balbon sp. nov. CASIZ 171406 (scale bar = 1mm); C. Hoplodoris rosans sp. nov. CASIZ 182921 (scale bar = 2mm). Abbreviations:A, ampulla; AG, accessory gland; AS, accessory spine; BC, bursa copulatrix; FGM, female gland mass; P, penis; PR, prostate; PS, penial spines; RS, receptaculum seminis; UD, uterine duct; V, vagina.

FIGURE 11. Hoplodoris, penial and accessory spines, scanning electron micrographs. A. Hoplodoris desmoparypha CASIZ 309550, penial spines; B. Hoplodoris desmoparypha CASIZ 309550, accessory spine; C. Hoplodoris balbon sp. nov. CASIZ 171406, penial spines; D. Hoplodoris balbon sp. nov. CASIZ 171406, accessory spine. E. Hoplodoris rosans sp. nov. CASIZ 182921, penial spines; F. Hoplodoris rosans sp. nov. CASIZ 182921, accessory spine.

FIGURE 13. Hoplodoris rosans sp. nov. CASIZ 182921. Radula, scanning electron micrographs. A. Jaw rodlets; B. Central teeth; C. Middle lateral teeth; D. Outer lateral teeth.