Chromodoris balat Bonomo & Gosliner 2020, sp. nov.
Creators: name: Bonomo, Lynn J.
name: Gosliner, Terrence M.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Nudibranchia
Chromodorididae
Chromodoris
Chromodoris balat

description: Chromodoris balat Bonomo & Gosliner sp. nov.
(Figs. 2A, 3, 4)
urn:lsid:zoobank.org:act: F4B47FEF-0F28-4701-A1C5-205BA105C686
Chromodoris sp. 12— Gosliner et al. 2018: 140, middle left photograph.
Goniobranchus striatellus — Gosliner et al. 2015: 227, middle right photograph, misidentification.
Chromodoris striatella —Gosliner et al. 2008: 225, middle photograph, misidentification.
Chromodoris striatella— Gosliner 2006: 90, Figure 5E, misidentification.
Type material. Holotype: NMP 041292 formerly from CASIZ 177676, one specimen, subsampled and dissected. Matotonngil Point, 13.71449° N 120.9087° E, Balayan Bay, Mabini (Calumpan Peninsula), Batangas Province, Luzon, Philippines, 17 m depth, 19 April 2008, T. M. Gosliner.
Type locality. Matotonngil Point, Balayan Bay, Mabini, Batangas Province, Luzon, Philippines.
External morphology. The living animal (Fig. 2A) is moderately large, with a length around 45 mm. Body is a cream-white color with dark brown broken lines running vertically down the mantle. At several random places along the mantle, large dark brown blotches or spots appear covering the lines. The marginal band includes yellow-orange broken spots around the outside with a white inner marginal band. In the white area, there are small orange, yellow, and red spots around the whole nudibranch. Seven tripinnate gill branches are red brown and have bright opaque white spots across them. The perfoliate rhinophores are red brown and have 22 distinct lamellae with bright opaque white spots. The posterior end of the foot barely extends past the end of the mantle and has the same marginal band and color patterns as the mantle. On either side of the mouth there is a pair of digitiform oral tentacles.
Internal anatomy. Mantle glands. The mantle glands are subcutaneous, but hard to see in the preserved specimen and are unable to be seen in photographs of the live animal. The mantle glands are highly branched and are blotchy in shape (Fig. 3A).
Buccal mass and radula. The muscular portion of the buccal mass is the same size as the oral tube length (Fig. 3B). A chitinous labial cuticle is found at the anterior end of the muscular portion with widely forked, bifurcated jaw elements that have rounded tips (Fig. 4A). The radular formula for the holotype, NMP 041292, is 76 x 57– 58.1.57–58. The rachidian tooth is thin and linear without a distinct cusp. On either side of the rachidian, the inner lateral teeth have 2–3 denticles on the inner side and 5–7 on the outer side (Fig. 4B). The inner lateral tooth has an elongate central cusp that is about three times the length of the adjacent denticles. The remaining laterals only have denticles on the outer side of the central cusp. The middle lateral teeth have an elongate cutting edge with 7 to 9 pointed denticles (Fig. 4C). The outer lateral teeth are rounded and elongate with 0, 1, 2, or 3 denticles depending on the amount of wear that has occurred on the teeth (Fig. 4D).
Reproductive system (Fig. 3C). The thin pre-ampullary duct connects the ovotestis with the curved elongate ampulla. The ampulla narrows proximally and divides into a short oviduct and an elongate vas deferens. The distal portion of the vas deferens is wide, convoluted, and prostatic. The prostatic portion narrows proximally and enters the short curved muscular ejaculatory segment. This segment expands into the very wide bulbous penial bulb, which also joins with the distal end of the vagina. The penial bulb contains numerous black pigment spots. The vagina is moderately long and straight and enters the base of the thin-walled, spherical bursa copulatrix. Just below the base of the bursa is the receptaculum seminis duct, which connects with the pyriform curved receptaculum seminis. Along the length of the receptaculum seminis duct is a short branch of the uterine duct that enters the female gland mass. The female gland mass is composed of a small albumen and membrane glands and a larger mucous gland. A small bulbous vestibular gland is present near the opening of the genital atrium.
Etymology. The name Chromodoris balat comes from the Filipino word for blotch or mark. Since the external morphology has strikingly large blotches across the mantle, we wanted to connote that with the name. The word balat in Filipino also comes with a negative connotation associated with birthmarks and means unlucky or misfortunate.
Geographical distribution. This species is only known from Matotonngil Point in the Philippines.
Remarks. In our molecular phylogeny C. balat is sister to Chromodoris lineolata (van Hasselt 1824). Our ABGD and bPTP analyses clearly show that they are distinct species. The minimum COI uncorrected pairwise distance between C. balat and C. lineolata is 2.79%. Externally, it differs from C. lineolata in having large brown blotches with areas of white and brown stripes, whereas C. lineolata has solid brown pigment and white lines, without blotches. Chromodoris striatella Bergh 1877 has a single medial blotch. In C. balat the orange marginal band is interrupted whereas it is continuous in both C. lineolata and C. striatella. Two other undescribed species found in Layton et al. (2018) are similar in external features, but they both lack distinctive brown blotches on the dorsal surface (see Chromodoris sp. 16 and Chromodori s sp. 17 in Gosliner et al. 2015). Chromodoris burni Rudman 1982, also has similar coloration with brown pigment and white longitudinal lines. However, it has orange rhinophores and gill that lack opaque white spotting. In Rudman (1982), Chromodoris clavata (Risbec 1928) was determined to be a synonym of C. striatella after Rudman compared two specimens of C. clavata from New Caledonia to C. striatella. From the original description and location of C. clavata, the physical attributes of C. balat do not match C. clavata and the biogeographical separation of the known locations of each species are fairly far apart. Chromodoris clavata has only two dark concentrations of brown pigment on either side of the mantle anterior to the gill and a solid continuous marginal band, indicating that C. balat is distinct from what Risbec documented from New Caledonia. Also, the radular teeth of C. balat are less acutely pointed than those of C. clavata and the inner lateral teeth have more denticles on the outer side of the central cusp.
Rudman (1982) illustrated the radular teeth of C. lineolata and C. striatella (Figs. 9, 10, respectively). In C. balat, the radular teeth are more strongly curved with a longer, sharper primary cusp than in the other two species. The reproductive systems of these C. lineolata, C. clavata, and C. striatella were not described and cannot be compared with the present species.
description: Published as part of Bonomo, Lynn J. & Gosliner, Terrence M., 2020, Adding stars to the Chromodoris (Nudibranchia, Chromodorididae) galaxy with the description of four new species, pp. 401-435 in Zootaxa 4819 (3) on pages 414-417, DOI: 10.11646/zootaxa.4819.3.1, http://zenodo.org/record/4397003