Chromodoris kalawakan 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 kalawakan

description: Chromodoris kalawakan Bonomo & Gosliner sp. nov.
Figures (2C, 2D, 2E, 7, 8)
urn:lsid:zoobank.org:act: F18F8F3B-E46E-426D-BD29-9C65185B9B16
Chromodoris sp. 23—Gosliner et al. 2008: 229, second from the top photograph.
Goniobranchus sp. 40— Gosliner et al 2015: 230, bottom right photograph.
Goniobranchus sp. 43— Gosliner et al 2018: 160, upper left photograph.
Type material. Holotype: CASIZ 109740, one specimen. Uchelbeluu Reef, Palau, 24 m depth, 10 mm length, 21 September 1996, T. M. Gosliner. Paratypes: CASIZ 178286, one specimen. NW Tutuba Island, 15.5500° S 167.2800° E, Tutuba Island, Vanuatu, 10 September 2006, M. Pola-Perez, Y. Camacho-Garcia et al. CASIZ 178300, one specimen, dissected, SE Matewulu, 15.4983° S 167.1983° E, Espiritu Santo Island, Vanuatu, 28 September 2006, M. Pola-Perez, Y. Camacho-Garcia et al. CASIZ 222016, one specimen, subsampled. South side of Lugbung Island between Nabagbagan Rocks and Logbon Sandbar, 12.58355°N 122.24380°E, Lugbung Island, Romblon Island, Romblon Province, Philippines, 3 April 2017, T.M. Gosliner. NMP 041293 (formerly from CASIZ 222019 a), one specimen, Cobrador Rocks, 12.65180°N 122.23113°E, Cabugaan Island, Cobrador Island (Naguso Island), Romblon Province, Philippines, 6 April 2017, J. Maestro. CASIZ 222019, one specimen, subsampled. Cobrador Rocks, 12.65180°N 122.23113°E, Cabugaan Island, Cobrador Island (Naguso Island), Romblon Province, Philippines, 6 April 2017, J. Maestro. CASIZ 224653, one specimen, subsampled and dissected. Bangug Island, 12.65212°N 122.23082°E, Romblon Island, Romblon Province, Philippines, 19 March 2018, K.L. Larkin. CASIZ 224654, one specimen, subsampled. Lugbong Island 12.58418°N 122.24429°E, Romblon Island, Romblon Province, Philippines, 18 March 2018, C. Alahado.
Type locality. Uchelbeluu Reef, Palau.
External morphology. Living animals (Fig. 2 C–E) are small, with a maximum length of 20 mm. Body is a translucent white or light gray color with bright opaque white spots across the body. The white spots are found on the tips of short conical projections. Some of the bright white spots are interconnected by diffuse opaque white lines. The marginal band includes small orange dots around the whole nudibranch. Nine to ten unipinnate gill branches that are white in color with bright opaque white spots and orange brown markings (Fig. 7A). The perfoliate rhinophores are white and have eight distinct lamellae with an orange accent at the top and the bright white opaque spots (Fig. 7B). The posterior end of the foot extends well beyond the posterior end of the mantle and is ornamented with a network of diffuse opaque white markings. On either side of the mouth there is a pair of digitiform oral tentacles.
Internal morphology. Mantle glands: The mantle glands are subcutaneous around the entire mantle margin, except for the anterior margin. There are approximately six mantle glands per side of the mantle (Fig. 7C). They are slightly yellower in color on the preserved holotype. The mantle glands in C. kalawakan are Y-shaped.
Buccal mass and radula: The muscular portion of the buccal mass is slightly smaller than the oral tube length. A chitinous labial cuticle is found at the anterior end of the muscular portion (Fig. 7D) with widely-forked, bifurcated jaw elements (Figs. 8 A–B). The radular formula in two paratypes, CASIZ 224653 and CASIZ 178300, is 43 x 32.1.32 and 43 x 29–31.1.29–31, respectively (Fig. 8C). The rachidian tooth is thin and linear without a distinct cusp. On either side of it, the inner lateral teeth have 1–3 denticles on the inner side and 2–3 on the outer side (Fig. 8D). The inner lateral tooth has an elongate central cusp that is about twice 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 3 to 7 acutely pointed denticles (Fig. 8E). The outer lateral teeth are elongate with 2 to 6 more rounded denticles (Fig. 8F).
Reproductive system (Fig. 7E): The thin pre-ampullary duct connects the ovotestis with the wider 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 muscular ejaculatory segment. This segment expands into the wider penial bulb, which also joins with the distal end of the vagina. The vagina is moderately long and curved and enters the base of the thin-walled, spherical bursa copulatrix. Also, joining at 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.
Etymology. This species is named Chromodoris kalawakan after the Filipino word for galaxy, since the coloration pattern looks like stars floating in a space cloud. The lines connecting some of the white dots appear as if astronomers were drawing the constellation patterns between the stars.
Geographical distribution. This species is known from Vanuatu, Indonesia, Philippines and Palau.
Remarks. In our molecular phylogeny, Chromodoris kalawakan is a member of a large, polytomous clade that includes: Chromodoris annae Bergh, 1877; Chromodoris elisabethina Bergh, 1877; C. lineolata; Chromodoris mandapamensis Valdés et al., 1999; Chromodoris michaeli Gosliner & Behrens, 1998; Chromodoris orientalis Rudman, 1983; Chromodoris quadricolor; C. striatella; Chromodoris strigata Rudman, 1982; and several undescribed species. The shortest uncorrected pairwise genetic distances for COI are of 10.07%, 10.07%, 10.77%, 9.20%, 10.94%, 9.72%, 9.97%, 8.86%, and 9.89% respectively to the described species stated in the previous sentence. This species was not included in the study by Layton et al. (2018) as it was originally thought to be a species of Goniobranchus.
Externally, C. kalawakan is the only species of Chromodoris that is entirely devoid of black lines or dark brown to black spots. It shares having white spots on the rhinophores and gill with several other species including, Chromodoris willani Rudman, 1982, C. lineolata, C. striatella, C. mandapamensis, and six undescribed species. Internally, the Y-shaped mantle glands in C. kalawakan are distinct from the more highly ramified mantle glands of other Chromodoris species that have been examined (Gosliner & Behrens 1998). The radula is smaller and contains fewer rows of radular teeth than do other species of Chromodoris, with a maximum of 43 rows of teeth. The rachidian teeth are short and narrow with a linear shape as in most other species of Chromodoris (Rudman 1982; Gosliner & Behrens 1998), whereas a rachidian row of teeth appears to be absent in Chromodoris africana Eliot, 1904; Chromodoris kuiteri Rudman, 1982; and Chromodoris joshi Gosliner & Behrens, 1998. Chromodoris willani is the only species that has a well-developed rachidian row of teeth that are large and triangular (Rudman 1982). Like most species of Chromodoris, C. kalawakan has a long prostatic portion of the vas deferens and short ejaculatory portion. The ABGD and bPTP analyses distinctive coloration of this species clearly differentiate it as a distinct 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 421-423, DOI: 10.11646/zootaxa.4819.3.1, http://zenodo.org/record/4397003