Tenellia ivetteae, Gosliner & Bertsch, 2017

Gosliner, Terrence M. & Bertsch, Hans, 2017, Two New Species of Nudibranch Mollusks from the Tropical Eastern Pacific of Mexico, Proceedings of the California Academy of Sciences 64 (6), pp. 117-130 : 126-128

Tenellia ivetteae sp. nov.

urn:lsid:zoobank.org:act:5BBF0CE1-0CAE-416A-83CB-8679AB637339

( Figs. 1C , 4B , 6 )

Cuthona sp. : Bertsch and Aguilar Rosas, 2016:301 (photo).

Cuthona sp. yellow: Bertsch, 2008:336; Bertsch, 2014:177.

Cuthona sp. 2 : Hermosillo, 2006:44, 131, 134.

Cuthona sp. 3 : Behrens and Hermosillo, 2005:131 (photo).

Cuthona sp. 4 : Hermosillo, Behrens and Ríos-Jara, 2006:134 (photo).

Cuthona sp. 6 : Camacho-García, Gosliner and Valdés, 2005:105 (photo).

MATERIAL EXAMINED.— Holotype: CASIZ 220143, 7 mm length, Punta la Gringa , Bahía de los Ángeles, Baja California, México, 30 June 1987, Sandra Millen . Paratypes: One specimen, CASIZ 222482 (dissected), Bahía de los Ángeles , Baja California, México, 30 June 1987, Sandra Millen ; Three specimens, CASIZ 220142, 6 mm, 3 m depth, 20 June 1992 (HB photo M3968) .

Additional records: Two specimens, 4 and 3 mm with egg masses, 4 m depth, Bahía de los Ángeles , Baja California, México, 25 July 1993; 1 animal, 3 mm, 10’ deep, 31 October 2003 . Twelve specimens, Majahuitas , Bahía de Banderas, Jalisco, México, between April 2002 – April 2005, Alicia Hermosillo (Hermosillo, 2006: 134) . One specimen, Punta Uvita , Punta Arenas, Costa Rica .

GEOGRAPHICAL DISTRIBUTION.— Thus far, known only from Bahia de los Angeles, Baja California, and Bahía de Banderas, Jalisco, in México, and Punta Uvita, Pacific coast of Costa Rica.

ETYMOLOGY.— This species is named in honor of Señorita Adriana Ivette Cadena, granddaughter of Señor Hans, who has helped with his research at Bahía de los Ángeles. She and her brothers and sisters—the children all around the world—remind us why we must do science and do it well: to present informed knowledge for informed decisions affecting their future and the life of our planet.

DESCRIPTION.— External morphology: The living animals ( Fig. 1C ) reach 7 mm in length. The body color is generally translucent white with dense opaque white spotting on the outer twothirds of the rhinophores and oral tentalces. The digestive gland within the cerata is yellowish cream white throughout the length of the cerata with a translucent white apex. The opaque white ovotestis follicles can be seen through the translucent body. The rhinophores are smooth, thin and cylindrical, slightly shorter than the narrower oral tentacles. The cerata are short and rounded with an acute apex where the cnidosac is located. They project outwards randomly, cover most of the notum, and are arranged in numerous linear rows. There are 3 rows in the precardiac ceratal rows. In four specimens, the three precardiac rows, beginning with the most anterior row, contain 1 – 4, 2 – 4, 3 – 4, cerata per row. After the interhepatic space, there are four postcardiac ceratal rows, each of which contains 1 – 4 cerata. The anus is acleioproctic, situated dorsally at the base of the upper ceras of the first postcardiac ceratal row. The genital opening is ventral to the first and second precardiac ceratal rows.

Buccal armature: The jaws are thin and elongate ( Fig. 6A ) with a long inner margin. The masticatory border of the jaw contains 31 simple acutely-pointed triangular denticles ( Fig. 6C ). The radular formula is 36 x 0.1.0 in the paratype specimen CASIZ. The central cusp is much wider and longer than the adjacent lateral denticles. There are 4 – 7 primary lateral cusps on either side of the wider central cusp ( Figs. 6B, D, E ) Secondary denticles between the primary lateral cusps are absent, although some denticles are shorter and narrower than the ones on either side of them.

Reproductive system: The reproductive system is androdiaulic ( Fig. 4B ). The ovotestis follicles contain a large female acinus surrounded by a series of smaller male acini. The ampulla is large and saccate and divides distally into the short oviduct and vas deferens that appears to have a glandular texture. The prostatic portion of the vas deferens is thin and narrows into a short, convoluted ejaculatory duct that joins the penis near the junction of the penial gland with the penial papilla. The penial gland is pyriform and curved, whereas the penial papilla is sausage-shaped, with a short, straight, cuticular penial stylet ( Figs. 6F, G ). The female glands are well-developed and small albumen and membrane glands are clearly visible, as is the larger mucous gland. A spherical bursa copulatrix is present at the distal end of the reproductive system and connects to the gonopore via a narrow elongate duct.

REMARKS.— Despite the lack of suitably preserved specimens of this species for molecular study, the presence of morphological features strongly suggest that it is correctly placed in the genus Tenellia . In the recent revision of Fionidae, Cella et al. (2016) , characterized Tenellia as including most members of the Fionidae having numerous well-separated ceratal rows with more than a single ceras per row. This is certainly the case in T. ivetteae . While it appears that not all species of Tenellia possess a penis armed with a straight penial stylet, the majority of species have this anatomical specialization, including T. ivetteae . Until fresh material is available to confirm the phylogenetic relationships and systematic status of T. ivetteae , we tentatively place it in Tenellia , based on the morphological attributes described above.

Tenellia ivetteae differs from all species of Fionidae previously documented from the temperate and tropical eastern Pacific. It is one of a handful of species that have whitish pigment as the predominant body color. Only T. albocrusta (MacFarland, 1966) and T. riosi ( Hermosillo and Valdés, 2008) comb nov., have a similar external appearance. Tenellia albocrusta is found the eastern Pacific from Alaska to La Paz, in the Gulf of California (Berhens and Hermosillo, 2005). In this species, the body is covered by irregular patches of opaque white and encrustaceans of opaque white on the cerata. In T. ivetteae , the opaque white is found only on the outer portions of the rhinophores and oral tentacles. The digestive gland within the cerata in T. albocrusta is green to brown whereas it is pale yellow in T. ivetteae . Tenellia riosi is known from only from the Bahía Banderas region of México. As in T. albocrusta , T. riosi has opaque white patches on the notum that are absent in T. ivetteae . It also has a black digestive gland basally in the cerata and salmon pink gland more distally. The shape of the radular teeth differs in the three species. In T. ivetteae , the central cusp of the tooth is longer than the adjacent denticles, whereas it is much shorter than the adjacent denticles in T. albocrusta (MacFarland, 1966, pl. 67, figs. 13, 14) and slightly shorter in T. riosi ( Hermosillo and Valdés, 2008, fig. 3a – c). In T. riosi the outer denticles are markedly shorter than the inner ones, whereas they are more evenly graduated in the other two species. The reproductive systems of the three species also differ. In T. albocrusta (MacFarland, 1966, pl. 69, fig. 4) and T. riosi ( Hermosillo and Valdés, 2008, fig. 2b), the prostatic portion of the vas deferens is much wider than the ejaculatory portion whereas they are about the same width in T. ivetteae . In T. ivetteae the bursa copulatrix is spherical and is found at the end of a long duct, whereas it is pyriform in both T. albocrusta and T. riosi and has a short duct in the latter species. In T. ivetteae the penial stylet is slightly curved where as it is sharply curved in T. albocrusta (MacFarland, 1966, pl. 69, fig. 4a) and appears to be absent in T. riosi ( Hermosillo and Valdés, 2008) .

Figures

FIGURE 1. Living animals. A. Rostanga ghiselini sp. nov., specimen from Punta Gringa, Bahía de los Angeles, 14 March 1992, photo by Hans Bertsch. B. Rostanga ghiselini sp. nov., holotype specimen from Punta Gringa, Bahia de los Angeles, 25 March 2017, photo by Craig Hoover. C. Tenellia ivetteae sp. nov., holotype, CASIZ 220143 (upper animal) and paratype, CASIZ (lower animal), from Punta Gringa, Bahia de los Angeles, 30 June 1992, photo by Hans Bertsch.

FIGURE 4. Reproductive anatomy. A. Rostanga ghiselini sp. nov., holotype, CASIZ 220373. B. Tenellia ivetteae sp. nov., paratype, CASIZ 222482. abbreviations: al-albumen gland, am ampulla, bc-bursa copulatrix, ej-ejaculatory portion of vas deferens, fg-female gland mass, me-membrane gland, mu-mucous gland, p-penis, pg-penial gland, pr-prostatic portion of vas deferens, rs-receptaculum seminis, st-penial stylet, v-vagina, vd-vas deferens, vg-vestibular gland. Scale = 1 mm.

FIGURE 6. Scanning electron micrographs, Tenellia ivetteae sp. nov. A, C-G. paratype, CASIZ 222482. B. Specimen from Bahia de los Ángeles, 30 June, 1987. A. Entire jaw. B. Radular teeth, dorsal view. C. Masticatory border of jaw showing arrangement of denticles. D. Dorsal view of radular teeth. E. Lateral view of radular teeth. F. Apex of penis showing stylet. G. Detail of stylet.