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 PERII GOSLINER & JOHNSON SP. NOV. (FIGS 2L, 13H, 18G, 23) LSID : urn:lsid:zoobank.org:act: 0E629152-88A2- 4635-B40C-C9B0BEF05659 Noumea sp. Debelius, 1997 : 218, middle photograph. Noumea sp. Coleman, 2001 : 84. Hypselodoris sp. 8. Debelius & Kuiter, 2007 : 123, middle photograph. Hypselodoris sp. 13. Gosliner et al. , 2015 : 261, upper right photograph. Type material Holotype : NMP 0 41281, (formerly CASIZ 182751 ), dissected, Mainit Bubbles , 13.6880278°N , 120.95809°E , Calumpan Peninsula , Mabini , Batangas , Luzon Island , Philippines , 40 m depth, 17 May 2010 , Peri Paleracio. Type locality Mainit Bubbles, Mabini, Batangas , Luzon Island, Philippines , 13.6880278°N , 120.95809°E . Geographical distribution Known only from Bali , Indonesia ( Debelius, 1997 ) and Batangas , Philippines from deep reefs ( Gosliner et al ., 2008 , 2015 ; present study). Etymology Hypselodoris perii is named for good friend and diver guide extraordinaire, Peri Paleracio, who found the first specimen of this species in the Philippines . Peri has discovered many new species of marine life in the Philippines , and it is a pleasure to honor his efforts with this new species. Description External morphology : Living animals ( Fig. 18G ) large, reaching 35 mm in length. Body translucent white, with wine-red medial line and scattered, elongate wine-red oval rings surrounded by diffuse purple pigment. Wide yellow to yellow–orange marginal band present along entire mantle margin. Wine-red ring encircling base of gill sheath. Translucent white foot ornamented by wine-red spots having larger areas of purple surrounding them. Eight unipinnate gill branches with translucent white base and bright redorange pigment on apical surfaces and outer margin. Perfoliate rhinophores uniformly bright red–orange, bearing ~17 densely arranged lamellae. Figure 23. Hypselodoris perii Gosliner & Johnson sp. nov. , holotype, NMP 0 41281, buccal armature. A, jaw rodlets. B, inner lateral teeth. C, middle lateral teeth. D, outer lateral teeth. Mantle glands : Subcutaneous mantle glands simple rounded in shape ( Fig. 2L ). Glands situated anteriorly and posteriorly, with no glands present along central regions of mantle margin. Four to five glands on either side of anterior end of the body, with an arc of 13 glands situated posteriorly. Buccal armature : Muscular portion of buccal mass approximately equal in length to oral tube. Buccal mass consisting of chitinous labial cuticle at anterior end of muscular portion of buccal mass. Jaws bearing numerous rodlets ( Fig. 23A ). Rodlets broadly triangular, with single acutely pointed apex. Radular formula of holotype 42 × 40.0.40. Rachidian row of teeth absent ( Fig. 23B ). Innermost lateral teeth have a single large, triangular denticle on inner side of bifid primary cusp and lacking outer denticles. Next several laterals lacking inner triangular denticle and lacking denticles on outer side of primary bifid cusps. Midlateral teeth ( Fig. 23C ) also lacking inner denticles but possessing two or three triangular outer denticles. Outer teeth lacking inner denticles and having two to five triangular outer denticles ( Fig. 23D ). Outermost teeth with narrower base and more elongate tooth shape. Reproductive system : Reproductive organs of holotype not fully mature, but arrangement of all major organs evident ( Fig. 13H ). Ampulla thick, tubular and slightly convoluted, narrowing somewhat before bifurcating into the oviduct and vas deferens. Short oviduct entering female gland mass near albumen gland. Prostatic proximal portion of vas deferens curved and thick, narrowing slightly while transitioning into muscular ejaculatory portion. Ejaculatory portion curving into segment entering short, enlarged penial bulb. Penial bulb adjacent to straight, slender 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. Elongate vagina leading to minute receptaculum seminis and larger spherical, thin-walled receptaculum seminis. Short uterine duct emerging from about half of the length along duct to bursa. Uterine duct relatively short and entering female gland mass near albumen gland. Remarks The colour pattern of H. perii clearly differentiates it from the all other described species. It is the only species with an elongate medial longitudinal reddish line and reddish oval markings. The most similar species is Hypselodoris dollfusi ( Pruvot-Fol, 1933 ), which was re-described by Gosliner & Behrens (2000) . Although both species are translucent white, with a yellow marginal band and wine-red and purple markings, there are numerous differences in the external colour pattern of the two species. Hypselodoris dollfusi lacks the medial longitudinal line that is present in H. perii . In H. dollfusi , the wine-red markings are narrow circles, which contain purple pigment. In contrast, H. perii has broad reddish ovals surrounded by diffuse purple pigment. In H. dollfusi , there are red and purple rings at the base of the rhinophores and the gill pocket, whereas in H. perii there is only a red ring at the base of the gill. In H. dollfusi , the gill and rhinophores are deep red, whereas they are red–orange in H. perii . The red pigment on the gill of H. dollfusi is restricted to the axis of each gill branch, whereas in H. perii the entire external surface of each gill branch is red–orange. Externally, both H. dollfusi and H. perii have anterior and posterior mantle glands and lack glands in the centre portion of the body. The glands are more numerous in H. dollfusi (12–18 anterior glands per side of the body and 22 posterior glands) vs. three or four anterior glands per side and 13 posterior glands in H. perii . Internally, there are also differences between the two species. The radular formula of H. dollfusi contains more rows of teeth (66 vs. 42) and more teeth per row than does the radula (88 vs. 40) of H. perii . In the single individual of H. dollfusi examined, the left inner lateral teeth had a single inner denticle, whereas the right inner laterals lacked a denticle. In H. perii , both the left and the right inner laterals bear a single denticle. In H. perii , the middle laterals bear two or three outer denticles, whereas the middle laterals of H. dollfusi lack denticles. Only the outer four to ten teeth of H. dollfusi bear outer denticles, whereas all of the middle and outer lateral teeth of H. perii have denticles. There are minor differences in the reproductive system of the two species, but given that the reproductive system of H. perii was not fully mature, it is difficult to make detailed comparisons based on the present material. The two species are geographically isolated, with H. dollfusi being restricted to the Arabian Sea and H. perii being known only from Bali and the Philippines . Unfortunately, no material suitable for molecular study is available for H. dollfusi . In the present molecular analysis, H. perii is sister to a large clade that includes members of the H. obscura , H. capensis ( Barnard, 1927 ), H. kaname and H. maritima clades. Gosliner & Behrens (2000) , based on morphological similarities, speculated that H. dollfusi was likely to be most closely related to the clade that includes H. paulinae , H. fucata and H. kaname . They noted that these four species shared three apomorphies: an erect rather than spreading branchial plume, a short jaw element shaft; and a receptaculum seminis that inserts into the vagina at the base of the bursa copulatrix. Hypselodoris perii also shares these characteristics. Our molecular studies place H. perii in close proximity to the clade that includes H. paulinae and H. kaname . Additional molecular studies that include H. fucata and H. dollfusi need to be conducted to explore these possible relationships further.