Hoplodoris balbon Donohoo & Gosliner 2020, sp. nov.
Creators: name: Donohoo, Samantha A.
name: Gosliner, Terrence M.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Nudibranchia
Discodorididae
Hoplodoris
Hoplodoris balbon

description: Hoplodoris balbon sp. nov.
(Figs. 7B, 8B, 10B, 11 C–D, 12)
urn:lsid:zoobank.org:act: F6B9A2AD-2DC5-46C1-A2F8-DE55407BFB84
Type material. Holotype: CASIZ 171406, one specimen, dissected, Balicasag Island, 9.51833° N 123.69167° E, Panglao, Bohol Island, Philippines, 4m depth, 25 June 2004, T. M. Gosliner, Y. Camacho-Garcia, J. Templado, M. Malaquias, and M. Poddubetskaia.
Type locality. Balicasag Island, Panglao, Bohol Island, Philippines.
External morphology. The living animals (Fig. 7B) are oval in shape, approximately 40–50 mm in length, and found along coral reefs at 4m in depth. The body color is tan with random brown flecks; numerous light brown and tan papillae with random elongate branches along a single stem; large, complex light brown and reddish-brown tu-bercles (Fig. 8B); and random white and dark brown blotches along the center and edge of the mantle. The underside of the mantle is tan with small to medium dark brown spots surrounding the foot. A wide band of brown scattered flecks that decrease in density towards the foot is offset from the mantle’s edge. The gill consists of six tan tripinnate branchial leaves that surround the anus with dark brown rachises and scattered light brown tips with opaque white spots. The gill pocket contains six lightly crenulated lobes with tan body coloration and numerous papillae. A large white spot is found anterior to the gill pocket. The rhinophores are perfoliate with 25–35 reddish-brown lamellae with scattered opaque white flecks. The two rhinophoral sheaths are lightly crenulated with similar coloration to the gill pocket and body. The foot is broad, anteriorly notched, and tan in color with numerous brown flecks across the whole foot. Flat, slightly rounded oral tentacles are present laterally on either side of the labial region and mouth.
Internal morphology. Buccal mass and radula. The buccal mass is muscular and anteriorly connects to a thin labial cuticle, which has elongated jaw rodlets, some of which have a rounded apex and others with a more irregular tip (Fig. 12A). The radula is composed of predominantly smooth hamate teeth and the radular formula is 36 × 66.0. 66 in the holotype CASIZ 171406. The inner lateral teeth (Fig. 12B) are short with a broad base and a strongly curved cusp. Some of the first 34 inner teeth have one to three triangular denticles along the outer side of the cusp. The middle lateral teeth (Fig. 12C) are larger and more elongate with a smooth, narrow cusp. The outer lateral teeth (Fig. 12D) are also larger and elongate, but have a slightly shorter, rounder smooth cusp than the middle lateral teeth; however, the two outermost teeth are reduced and semi-fimbriate.
Reproductive system. An elongate ampulla loops and then abruptly narrows into the vas deferens and a short oviduct (Fig. 10B). The vas deferens expands into the rounded portion of the prostate, which then narrows distally into a short, muscular ejaculatory duct and expands again into the bulbous penis that shares a common genital atrium with the accessory gland. The penis is armed with numerous stubby, conical-shaped penial spines with scalloped edges that are attached to a fleshy stem (Fig. 11C). An elongate, narrow vagina enters an irregular bursa copulatrix that is smaller than the prostate and connects to the base of the accessory gland. A short duct connects near the base of the bursa to a small, ovate receptaculum seminis. A short uterine duct connects to the base of the receptaculum and enters the female gland mass. An irregular-shaped nodular accessory gland is connected to the common genital atrium by a narrow, elongate, convoluted duct. Within the base of the accessory gland is a large, slightly curved accessory spine with a semi-broad base attached to a fleshy stem (Fig. 11D).
Etymology. This species is named Hoplodoris balbon after the Filipino word for hairy i.e. “balbon” due to the large, compound tubercles covering the mantle.
Geographical distribution. Known only from Panglao, Philippines.
Remarks. Due to the original preservation in formalin, molecular sequencing of the holotype of H. balbon (CASIZ 171406) was unsuccessful for all genes studied; however, the morphological characteristics are sufficiently distinct to distinguish H. balbon as a new species within Hoplodoris. Externally, the body coloration of H. balbon is tan with numerous complex light brown and reddish-brown tubercles, and light brown compound papillae, while H. desmoparypha is either cream or white in coloration with brown to dark brown irregular blotches, light brown to reddish brown tubercles, and light brown papillae. The presence of a unique white spot anterior to the gill also appears to be distinctive. The number of gills is similar between species, but the coloration of the leaves and rachis varies. In H. balbon the branchial leaves are tan with dark brown rachis and light brown tips, while in H. desmoparypha the branchial leaves are purplish-brown with purplish-brown rachis and light brown tips. The coloration of the rhinophores is similar; however, the lamellae in H. balbon are more reddish-brown then those in H. desmoparypha.
The jaw rodlets are also similar between H. balbon and H. desmoparypha, but, the rodlets in H. balbon are much more elongate with either rounded or irregular tips. The radular teeth in H. balbon and H. desmoparypha are mostly similar in shape and size; however, the presence and consistency of denticles and the shape of the inner lateral teeth vary between the species. In H. balbon the inner lateral teeth have a small base, but a much more elongate cusp then the larger inner lateral teeth in H. desmoparypha (Bergh 1880, plate F, figs. 1–2). Denticles are found along some of the inner lateral teeth in both H. balbon and H. desmoparypha; while, only H. desmoparypha has denticles on the middle and outer lateral teeth. The shape of the outermost tooth in H. balbon is also similar to the outermost tooth found in H. desmoparypha i.e. reduced and semi-fimbriate (Bergh 1880, plate F, fig. 4). The reproductive system of H. balbon has a semi-large rounded prostate armed with conical penial spines elevated on stems, a smaller irregular shaped bursa copulatrix, and a much smaller receptaculum seminis; whereas, H. desmoparypha has an irregular prostate which is also armed with conical penial spines, a large rounded bursa copulatrix, and a small receptaculum seminis (Bergh 1880, plate F, fig. 5; Dayrat 2010, fig. 200B). The size and shape of the accessory gland and accessory spine also varies between species. In H. balbon the accessory gland is much smaller and elongate on a fleshy base with a slightly curved accessory spine, while H. desmoparypha has a slightly larger, more irregularly shaped accessory gland with a broader, curved sessile spine (Bergh 1880, plate F, figs. 5, 12‾14; Dayrat 2010, fig. 203B). Though intra-specific variation is not studied here due to the unavailability of additional specimens, H. balbon is supported as a distinct species from H. desmoparypha based on strong external and internal morphological differences.
description: Published as part of 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, pp. 1-37 in Zootaxa 4890 (1) on pages 16-18, DOI: 10.11646/zootaxa.4890.1.1, http://zenodo.org/record/4301483