Chromodoris aff. mandapamensis

Bonomo, Lynn J. & Gosliner, Terrence M., 2020, Adding stars to the Chromodoris (Nudibranchia, Chromodorididae) galaxy with the description of four new species, Zootaxa 4819 (3), pp. 401-435 : 424-425

Chromodoris aff. mandapamensis

Figures (2F, 9, 10)

Chromodoris sp. 15— Gosliner et al. 2018: 140, bottom right photograph.

Material examined. CASIZ 181260 , one specimen, subsampled and dissected. Ligpo Island , 13.82012°N 120.9004° E, Balayan Bay , Batangas Province, Luzon Island, Philippines, 15 May 2009, Roger Steene .

Geographical distribution. The only known specimen was found at Ligpo Island in the Philippines.

External morphology. The living animal ( Fig. 2 ) was small, with a length around 18 mm. The body is an opaque white color with many black spots surrounded by a grey color forming a figure eight around the rhinophores and the gill. In the center of the figure eight there are some pale orange spots. The marginal band has discontinuous orange spots along the margin. There are five unipinnate gill branches that are bright orange with bright, opaque white spots across them. The perfoliate rhinophores are bright orange and have twelve distinct lamellae with bright opaque white spots. The posterior foot barely extends past the end of the mantle and has the same discontinuous orange spots along the marginal band. On either side of the mouth there is a pair of digitiform oral tentacles.

Internal morphology. Buccal mass: The muscular portion of the buccal mass is slightly larger than the oral tube length. A chitinous labial cuticle is found at the anterior end of the muscular portion ( Fig. 9 ) with forked, bifurcated jaw elements that have rounded tips ( Figs. 10 A–B). The radular formula for the specimen, CASIZ 181260, is 53 x 38.1.38 ( Fig. 10C ). The rachidian tooth is thin and linear without a distinct cusp and has a wide base that is triangular in shape. On either side of the rachidian, the inner lateral teeth have 2–3 denticles on the inner side and 2–3 on the outer side ( Fig. 10D ). The inner lateral tooth has an elongate central cusp that is slightly longer than 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 4 to 7 widely-spaced, pointed denticles ( Fig. 10E ). The outer lateral teeth are rounded and elongate with 4 to 6 denticles depending on the amount of wear that has occurred on the teeth ( Fig. 10F ).

Reproductive system: The reproductive structure is not fully developed because the single known specimen is a juvenile.

Remarks. This species is distinct based on our molecular phylogeny and subsequent ABGD and bPTP analyses where it is sister to C. mandapamensis , from the Indian Ocean. The bPTP analysis reached convergence and has a probability of 0.94 that C. mandapamensis and C. aff. mandapamensis are distinct species from one another and an uncorrected pairwise distance of 2.0% for COI gene. However, this differs from the results found by Tibiriçá et al. (2020), which found them to be the same taxa. Some possibilities to pursue to resolve these alternating results are that the C. mandapamensis sequenced in Layton et al. (2018) is not the true C. mandapamensis and is not from the type locality ( India). Therefore, this could potentially not be a true C. mandapamensis . Additionally, C. aff. mandapamensis is similar in characteristics to a juvenile form of Goniobranchus pruna ( Gosliner 1994) , however molecular data are not available for G. pruna . Molecular data need to be obtained from G. pruna and further morphological comparisons need to be made to distinguish if these species are the same or different. We did not choose to describe C. aff. mandapamensis here since it is known solely from a single juvenile specimen and further comparisons with additional adult specimens is required. Chromodoris aff. mandapamensis is included in the descriptions because the radula and jaws are distinct enough from C. mandapamensis that we wanted to have a record of those differences for potential future use in descriptions.

Figures

FIGURE 2. A. Chromodoris balat sp. nov. NMP 041292, Philippines; B. Chromodoris baqe sp. nov. CASIZ 192285, Red Sea; C–E. Chromodoris kalawakan sp. nov. C. CASIZ 109740, Palau; D. CASIZ 178300, Vanuatu; E. CASIZ 222016, Philippines; F. Chromodoris aff. mandapamensis, CASIZ 181260, Philippines; G–H. Chromodoris quagga sp. nov. G. CASIZ 184320, Philippines; H. CASIZ 229987, Philippines. Photos: T.M. Gosliner.

FIGURE 9. Chromodoris aff. mandapamensis, CASIZ 181260, buccal mass (scale bar = 0.1 mm). Abbreviations: bb, buccal bulb; ot, oral tube; ra, radular sac.

FIGURE 10. Scanning electron micrographs. Chromodoris aff. mandapamensis, CASIZ 181260, Philippines. A. Jaw; B. Jaw rodlets; C. Radula; D. Central teeth; E. Mid-lateral teeth; F. Outer lateral teeth.