Reading between the lines: revealing cryptic species diversity and colour patterns in Hypselodoris nudibranchs (Mollusca: Heterobranchia: Chromodorididae) Author Epstein, Hannah E. Author Hallas, Joshua M. Author Johnson, Rebecca Fay Author Lopez, Alessandra Author Gosliner, Terrence M. text Zoological Journal of the Linnean Society 2018 2018-09-14 20 1 1 74 journal article 27363 10.1093/zoolinnean/zly048 49bea467-fac6-484a-9902-05483dec9a52 2632578 urn:lsid:zoobank.org:pub:F0065FD2-417C HYPSELODORIS CERISAE GOSLINER & JOHNSON SP. NOV. (FIGS 1C, 2B, 4E, 6) LSID : urn:LSID:zoobank.org:act: A53FA948-8E58- 47A8-9BA3-681900B19537 Hypselodoris krakatoa ? misidentification, not H. krakatoa Gosliner & Johnson, 1999 ; Garthwaite, 2002 ; Masayoshi, 2002 . Type material Holotype : CASIZ 178350 , subsampled for molecular study, Long Dong , Taipei County , Taiwan , 10 m depth, 9 August 2008 , C. Chen. Paratypes : CASIZ 219744 , Sokoda , Hachijo Island , Japan , 7 m depth, 1 July 2001 , Nishina Masayoshi . CASIZ 175726 , subsampled for molecular study, Rayner’s Rock , off Pulau Aur , Malaysia , 20 m depth, 3 October 2007 , T. Gosliner . Comparative material examined: H. krakatoa Gosliner & Johnson, 1999 . Type locality Long Dong, Taipei County, Taiwan . Geographical distribution Known from Japan , Taiwan and Malaysia . Figure 6. Hypselodoris cerisae Gosliner & Johnson sp. nov. A, entire jaw, holotype, CASIZ 178350. B, jaw rodlets, paratype, CAS 175726. C, jaw rodlets, holotype, CASIZ 178350. D, inner lateral teeth, holotype, CAS 178350. E, middle lateral teeth, holotype, CASIZ, 178350. F, outer lateral teeth, paratype, CAS175726. Etymology Hypselodoris cerisae is named for Cerise Chen, who first found this species in Taiwan and collected the holotype specimen. Cerise has a keen interest in octocoral biology but also a more general interest in marine biodiversity. Description External morphology : Living animals ( Fig. 1C ) moderately large, reaching 20–35 mm in length. Colour pattern complex with golden honey ground colour. Notum ornamented with purple on anterior, lateral and posterior margins. Irregular dark brown to black longitudinal lines present on notum, with few opaque white spots along sides of dark lines. Gill pocket well elevated from notum. Seven to nine narrow, thin, unipinnate gill branches on notum. Gill branches red–orange on upper outer surface, opaque white internally and externally at base. Rhinophores uniformly bright red–orange except at opaque white apex. Rhinophores with ~21 small lamellae, Edge of foot with purple marginal band. Mantle glands : Subcutaneous mantle glands ( Fig. 2B ) uniformly distributed along entire margin in the specimens from Taiwan (CASIZ 178350) and Japan (CASIZ 219744), but absent from some portions of the lateral edges in the specimen from Malaysia (CASIZ 175726). Buccal armature : Muscular portion of buccal mass slightly larger than length of oral tube. Chitinous labial cuticle found at anterior end of muscular portion of the buccal mass ( Fig. 6A ) bearing numerous jaw rodlets ( Fig. 6B, C . Rodlets narrow with short base and evenly curved, with single, acutely pointed apex and occasional lateral flange. Radular formula of holotype (CASIZ 178350) 59 × 36.0.36 and paratype (CAS 175726) 52 × 56.0.56. Rachidian row of teeth absent ( Fig. 6D ). Innermost lateral teeth having one to two triangular denticles on inner side of bifid primary cusp. Denticles absent from outer side of tooth ( Fig. 6D ). Next several laterals and middle lateral teeth ( Fig. 6D, E ) with bifid cusp, lacking inner or outer denticles. Outermost one to three teeth having a narrower base and shorter tooth shape, with one to five rounded outer denticles ( Fig. 6F ), smaller than bifid cusps. Reproductive system : Reproductive organs of the holotype ( Fig.4E ) and one paratype (CASIZ175726) fully mature and virtually identical anatomically. Ampulla thick, short, tubular and slightly curved, narrowing somewhat before bifurcating into oviduct and vas deferens. Short oviduct entering female gland mass near albumen gland. Prostatic proximal portion of vas deferens relatively short, convoluted, curved and thick and narrowing slightly as it transitions into muscular, ejaculatory portion. Ejaculatory portion relatively short, convoluted, narrow, entering short, wider penial bulb. Penial bulb adjacent to slightly curved, wide vaginal duct at common gonopore. Distal end of vas deferens devoid of penial hooks. Female gland mass consisting of large mucous gland and small membrane and albumen glands. Large, lobate vestibular gland situated near exit of mucous gland. Relatively long vagina leading to small, straight receptaculum seminis and larger spherical, thinwalled receptaculum seminis. Receptaculum seminis appressed against vagina, near middle of vagina. Moderately short uterine duct emerging from vagina opposite receptaculum, entering female gland mass, near albumen gland. Remarks The colour pattern of H. cerisae is similar to that of H. krakatoa Gosliner & Johnson, 1999 , but differs in several consistent respects. In H. cerisae , the body has much more pink to purple pigment, whereas in H. krakatoa the notum is suffused with patches of burnt orange. Both species have prominent purple pigment on the anterior margin of the mantle, but in H. cerisae the posterior end is also purple, whereas it is burnt orange in H. krakatoa . The body appears lower and wider in H. cerisae than in H. krakatoa , but in H. krakatoa the mantle margin is more extensive laterally, overhanging the lateral edges of the body. There are seven to nine gill branches in H. cerisae and only six or seven in H. krakatoa . The mantle glands are distributed in a similar manner in both species, where they are largely uniformly spaced around the entire mantle margin. In our molecular analysis ( Fig. 35 ), H. cerisae is sister to a clade that includes H. jacksoni Wilson & Willan, 2007 , H. reidi Gosliner & Johnson, 1999 and H. iba sp. nov. Additionally, H. krakatoa and H. reginae Marcus & Marcus, 1970 form a trichotomy with the clade that includes H. cerisae . All members of this largest clade have a gill peduncle that is well elevated from the notum. The shape of the jaw rodlets and radular teeth is also similar in H. cerisae and H. krakatoa , but the number of teeth per radular row differs. In the two specimens of H. cerisae (CASIZ 178350 and 175726) the radula formula was 59 × 36.0.36 and 52 × 56.0.56, respectively. In four specimens of H. krakatoa the radula formula was 57 × 74.0.74 (CASIZ 206801; Fig. 7 ), 57 × 72.0.72 (CASIZ 177371), 51 × 66.0.66, 46 × 60.0.60 and 30 × 35.0.35 (last three from Gosliner & Johnson, 1999 ). Generally, the radula of H. cerisae has fewer lateral teeth per row than that of H. krakatoa . The reproductive system of H. cerisae has several consistent differences from that of H. krakatoa (CASIZ 206801; Fig. 4F ). In H. cerisae , the vagina is shorter and wider than that of H. krakatoa , and the uterine duct and receptaculum seminis are situated more distally than in H. krakatoa , where the uterine duct and receptaculum are immediately below the bursa copulatrix.