Trapania tigger, Smirnoff & Donohoo & Gosliner, 2022

Smirnoff, Dimitri S., Donohoo, Samantha A. & Gosliner, Terrence M., 2022, Extra-branchial processes manifest extra diversity: systematics of the genus Trapania (Nudibranchia: Goniodorididae) and nine new species descriptions, Zoological Journal of the Linnean Society 196, pp. 270-313 : 295

TRAPANIA TIGGER SP. NOV.

( FIGS 2H , 4H , 11 )

Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 3295F8AD-8D24-4204-A98E-8F6910B14367.

Trapania sp. 6 Nakano, 2004: 95 , top photograph.

Trapania sp. 7 Gosliner et al., 2015: 143, bottom-left photograph.

Trapania sp. 8 Gosliner et al., 2018: 61, middle-right photograph.

Type material: Holotype: NMP 041328 , originally CASIZ 180412 , one specimen, dissected and sequenced, Mabini , Batangas Province, Luzon Island, Philippines, November 2008, collected by Peri Paleracio.

Type locality: Mabini , Batangas Province, Luzon Island, the Philippines .

Geographical distribution: Known only from Mabini, Luzon, the Philippines.

Etymology: Trapania tigger is named for its resemblance to Tigger, a fictional character illustrated by E. H. Shepard from the Winnie-the-Pooh series of stories ( Milne, 1928). It is a noun in apposition.

External morphology: Living animal ( Fig. 2H ) is 12 mm. Entire body is mottled pale tan with darker brown patches and a few small opaque white spots over the entire surface of the body. Posterior portion of the body has alternating bands of light and dark pigment, while the middle and anterior of the body is characterized by discrete light and dark patches of pigment. Rhinophores are thick, club-shaped with about eight lamellae and a pointed tip. The small gill has a central, branching stalk flanked by two smaller branches. The extra-branchial and extra-rhinophoral appendages are thick, stocky and have a slight bulge near the base. The anterior margins of the foot extend laterally as elongate appendages. Oral tentacles are short. Posterior foot is bluntly rounded and less pointed than typical of Trapania .

Buccal mass: The buccal mass is muscular with a moderately developed buccal pump on the dorsal surface. Inside the anterior portion of the mass is a pair of welldeveloped jaws. The jaws contain several rows of acutely pointed, slightly curved, cylindrical jaw elements, equally spaced with regularly sized gaps ( Fig. 11A ). The radular formula of the holotype is 50 × 1.0.1 ( Fig. 11B ). The older teeth are much smaller than the newer ones and the radula widens towards the more newly developed teeth. The teeth bear numerous denticles with the smallest ones being found on the inner edge of the tooth. There are approximately five to ten denticles on the inner side of the much larger narrow primary cusp and one denticle on the outer side of the cusp. The older teeth ( Fig. 11C ) have fewer denticles than the more recently developed ones ( Fig. 11D ). Some of the larger more recently formed teeth have small denticles between some of the adjacent larger ones.

Reproductive system: The mature reproductive system is triaulic ( Fig. 4H ). The tubular pre-ampullary duct is narrow where it connects to the ovotestis. From there it abruptly widens into the saccate ampulla proper, which leads to a point where it divides into the short oviduct and vas deferens. The oviduct enters the female gland mass. The vas deferens gradually widens into a prostatic portion and gradually transitions into the narrow, muscular ejaculatory portion that is continuous with the narrow penial sac. The penial sac terminates at the gonopore adjacent to the vagina. The narrow vagina maintains its width from its opening through a long region prior to its junction with the large, pyriform bursa copulatrix and short, narrow receptaculum duct. The receptaculum duct joins the spherical receptaculum seminis near the long division of the uterine duct, which enters the female gland mass. The female gland mass is composed of the large mucous gland and the smaller albumen and membrane glands.

Remarks: In our molecular phylogeny Trapania tigger is sister to a clade that contains T. reticulata and T. darvelli . Our ABGD analysis and bPTP analysis reveal a strong genetic divergence of 8.0% in the COI gene and 8.2% in the 16S gene between T. tigger and T. reticulata and 8.7%/7.7−8.2% between T. tigger and T. darvelli , further supporting T. tigger as a distinct species within Trapania ( Tables 3 , 4 ). These three species are uniquely characterized by having thick extra-rhinophoral and extra-branchial appendages, thick rhinophores and a relatively blunt posterior end of the foot. Both T. tigger and T. reticulata have mottled brownish pigment, but in T. tigger the pattern occurs as distinct dark and light patches, whereas T. reticulata has brownish pigment surrounding yellow spots. In contrast, T. darvelli has a translucent white body with brown on the rhinophores, oral tentacles, extrarhinophoral and extra-branchial appendages and gill. All three species have radular teeth with a single, large cusp situated near the outside of the tooth and a series of smaller denticles on the inside of the cusp. In T. tigger and T. darvelli there are few denticles on the inside of the cusp (five to ten) as compared to T. reticulata (11– 18 denticles in largest teeth). The reproductive systems of T. tigger , T. reticulata and T. darvelli have significant differences. In T.tigger and T.reticulata , the pre-ampulla enters the proximal end of the ampulla subterminally, whereas it enters the proximal ampulla terminally in T. darvelli . In T. tigger , the penial sac is narrow and is the same width as the ejaculatory portion of the vas deferens, whereas in T. reticulata and T. darvelli the penial sac is much wider than the short ejaculatory portion. The bulbous penial sac of T. darvelli is short in T. darvelli and elongate in T. reticulata . Both T. tigger and T. reticulata have a straight vaginal duct, while it is curved in T. darvelli . In T. tigger and T. reticulata , the bursa copulatrix and receptaculum seminis are about the same size, while the bursa of T. darvelli is much larger than the receptaculum.

Figures

Figure 2. Living animals. A, Trapania japonica (Baba, 1935), CASIZ 221116, Mabini, Batangas, Philippines, photo by Peri Paleracio. B, Trapania tatsulok sp. nov., holotype, NMP 041333 (formerly CASIZ 200530), Calatagan, Batangas, Philippines. C, Trapania kahel sp. nov., holotype, NMP 041330 (formerly CASIZ 186131), Mabini, Batangas, Philippines. D, Trapania lemanioides sp. nov., holotype, NMP 041335 (formerly CASIZ 208433), Puerto Galera, Mindoro Oriental, Philippines. E, Trapania lemanioides sp. nov., paratype, CASIZ 221979, Romblon, Philippines. F, Trapania aurata Rudman, 1987, CASIZ 186205, Mabini, Batangas, Philippines. G, Trapania reticulata Rudman, 1987, CASIZ 191431, Madang, Papua New Guinea, photo by Vanessa Knutson. H, Trapania tigger sp. nov., holotype, NMP 041328 (formerly CASIZ 180412), Mabini, Batangas, Philippines, photo by Alicia McKowen. Photo by T. Gosliner unless indicated.

Figure 4. Reproductive systems. A, Trapania japonica (Baba, 1935), CASIZ 221116, scale = 0.50 mm. B, Trapania tatsulok sp. nov., holotype, NMP 041333 (formerly CASIZ 200530), scale = 0.33 mm. C, Trapania kahel sp. nov., holotype, NMP 041330 (formerly CASIZ 186131), scale = 0.28 mm. D, Trapania lemanioides sp. nov., holotype, NMP 041335 (formerly

Figure 11. Trapania tigger sp. nov. Scanning electron micrographs of buccal armature of holotype NMP 041328 (formerly CASIZ 189412). A, jaw with rodlets. B, entire radular ribbon. C, older radular teeth. D, newly formed radular teeth.