Hypselodoris brycei, Gosliner & Johnson, 2018

Epstein, Hannah E., Hallas, Joshua M., Johnson, Rebecca Fay, Lopez, Alessandra & Gosliner, Terrence M., 2018, Reading between the lines: revealing cryptic species diversity and colour patterns in Hypselodoris nudibranchs (Mollusca: Heterobranchia: Chromodorididae), Zoological Journal of the Linnean Society 20 (1), pp. 1-74 : 12-14

HYPSELODORIS BRYCEI GOSLINER & JOHNSON SP. NOV.

(FIGS 1B, 4C, 5)

LSID: urn:lsid:zoobank.org:act:CBB7E0BA-43CF-47E7-9371-5FD79772D571

C h r o m o d o r i s b u l l o c k i m i s i d e n t i f i c a t i o n, n o t C. bullockii Collingwood, 1881 , Wells & Bryce, 1993: 8, upper figure.

H y p s e l o d o r i s b u l l o c k i m i s i d e n t i f i c a t i o n, n o t H. bullockii ( Collingwood, 1881) , Debelius, 1997: 233 uppermost photograph.

Hypselodoris cf. bullocki 2 Debelius & Kuiter, 2007: 117, upper photographs.

Hypselodoris sp. 9 Gosliner et al., 2008: 268, bottom photograph.

Hypselodoris sp. 18 Gosliner et al., 2015: 263, upper left photograph.

Type material

Holotype: WAM S96082 , subsampled for molecular study, Epsilon Island, Montebello Islands , Western Australia, 20.4513°S, 115.5827°E, 7 m depth, 15 April 2015, S. Morrison.

Paratypes: WAM S96083 , subsampled for molecular study, Western Australia, 20.4513°S, 115.5827°E, 7 m depth, 15 April 2015, A. Hara and A. Hosie . WAM S96157 , subsampled for molecular study, 5.2 km NE of Ah Chong Island, Montebello Islands, Western Australia, 20.4992°S, 115.5899°E, 15 m depth, 16 April 2015, A. Hara. WAM 12628, five specimens, one dissected, St. 16, Dampier Archipelago, NW Legendre Island , Western Australia, 31 July 2000, C. Bryce .

Type locality

Epsilon Island, Montebello Islands.

Geographical distribution

Known only from the Houtman Abrolhos Islands to the Exmouth Region and Dampier Archipelago, Western Australia ( Wells & Bryce, 1993; Debelius, 1997).

Etymology

Hypselodoris brycei is named for our colleague, Clay Bryce of the Western Australian Museum, who has collected and photographed very many new species of nudibranchs. He was the first to document this new species and has collected most of the material studied here.

Description

Externalmorphology: Livinganimals( Fig.1B )moderately large, reaching 50 mm in length. Body translucent white, with a deep violet marginal band encircling the margin of notum. More purple submarginal pigment found inside marginal band. Nine to 11 thin, unipinnate gill branches on notum. Gill branches with purple base and red–orange outer two-thirds. Base of gill pocket purple. Bulb and base of rhinophores bright red orange, with ~41 small lamellae. Base of rhinophore sheath deep violet to purple. Edge of foot with purple marginal band.

Mantle glands: Subcutaneous mantle glands entirely absent.

Buccal armature: Muscular portion of buccal mass about twice length of oral tube. Chitinous labial cuticle found at anterior end of muscular portion of the buccal mass bearing numerous jaw rodlets ( Fig. 5A ). Rodlets narrow, with short base and evenly curved, with single, acutely pointed apex. Radular formula of one paratype, WAM 12628, ~70 × 92.0.92. Rachidian row of teeth absent ( Fig. 5B ). Innermost lateral teeth having one rounded denticle on inner side of bifid primary cusp with another three to four outer denticles. Denticles not extending far beyond middle of elongate primary cusp. Next several laterals lacking inner triangular denticle but possessing four to six denticles on outer side of primary bifid cusps. Midlateral teeth ( Fig. 5C ) all lacking inner denticles, but having five to nine rounded, triangular outer denticles and extended primary cusp. Outermost teeth having a narrower base and shorter tooth shape, with five or six rounded outer denticles ( Fig. 5D ), often larger than bifid cusps.

Reproductive system: Reproductive organs of the holotype fully mature ( Fig.4C ). Ampulla thick, 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 convoluted, curved and thick and narrowing slightly as it transitions into muscular ejaculatory portion. Prostatic portion enveloping bursa copulatrix. Ejaculatory portion convoluted, narrow, entering short, wider penial bulb. Penial bulb adjacent to slightly curved, moderately 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, thin-walled receptaculum seminis. Receptaculum seminis appressed against vagina. Moderately long uterine duct emerging from vagina close to base of bursa and female gland mass, near the albumen gland.

Remarks

The colour pattern of H. brycei is distinctive from all other members of the genus. It most closely resembles Thorunna daniellae ( Kay & Young, 1969) ( Gosliner et al., 2015: 250 upper right photograph), but H. brycei is a larger species, reaching 50 mm in length, whereas T. daniellae rarely exceeds 20 mm in length. Our molecular phylogeny ( Fig. 35 ) clearly indicates that H. brycei is in the H. bullockii clade, where it is the sister species to H. apolegma ( Yonow, 2001) . Yonow (2001) described H. apolegma as a species of Risbecia , but Johnson & Gosliner (2012) clearly demonstrated that Risbecia is nested within Hypselodoris and that H. apolegma is not in the same clade as the species formerly included in Risbecia but is closely related to H. bullockii . Of the members of the H. bullockii clade, H. brycei is the only species with a white body colour and a violet marginal band. All members of the H. bullockii clade lack mantle glands and are unique among Hypselodoris species in this regard. The radula of H. apolegma appears to contain more teeth than that of H. brycei ( Yonow, 2001; present study). Yonow (2001) described the radula formula of H. apolegma as 96 × 120.0.120, whereas the specimen of H. brycei had a formula of 70 × 92.0.92. The denticles of the radular teeth of H. brycei do not extend much beyond the middle of the primary cusp, whereas in H. apolegma they extend almost to the end of the cusp. The reproductive system of H. brycei has a much shorter penial papilla and long ejaculatory duct, whereas H. apolegma ( Fig. 4D ) has a longer, wider penial bulb and a shorter ejaculatory duct.

Figures

Figure 1. Living animals. A, Hypselodoris alburtuqali Gosliner & Johnson sp. nov., CASIZ 192295, holotype, Saudi Arabia. B, Hypselodoris brycei Gosliner & Johnson sp. nov., WAM S96082, holotype, Montebello Islands, Western Australia, photograph by Nerida Wilson. C, Hypselodoris cerisae Gosliner & Johnson sp. nov., specimen from Hachijo Island, Japan, Nishina Masayoshi. D, Hypselodoris confetti Gosliner & Johnson sp. nov., CASIZ 191070, Papua New Guinea, photograph by J. Goodheart. E, Hypseldoris ghardaqana (Gohar & Abu-Ela, 1957), CASIZ 192282, Saudi Arabia. F, Hypselodoris juniperae Gosliner & Johnson sp. nov., CASIZ 177550, Radama Islands, Madagascar. G, Hypselodoris katherinae Gosliner & Johnson sp. nov., CASIZ 176773, eastern Peninsular Malaysia. H, H. katherinae Gosliner & Johnson sp. nov., CASIZ 177532, Batangas, Luzon, Philippines. I, H. katherinae Gosliner & Johnson sp. nov., CASIZ 181300, Batangas, Luzon, Philippines. All photographs by T. Gosliner unless otherwise indicated.

Figure 4. Reproductive systems A, Hypselodoris alburtuqali Gosliner & Johnson sp. nov., holotype, CASIZ19229, scale bar: 0.5 mm. B, Hypselodoris maculosa (Pease, 1871), CASIZ 139595, scale bar: 0.75 mm. C, Hypselodoris brycei Gosliner & Johnson sp. nov., paratype, WAM S12628, scale bar: 3.0 mm. D, Hypselodoris apolegma (Yonow, 2001), CASIZ 083743, scale bar: 2.0 mm. E, Hypselodoris cerisae Gosliner & Johnson sp. nov., holotype CASIZ 178350, scale bar: 0.85 mm. F, Hypselodoris krakatoa Gosliner & Johnson, 1999, CASIZ 206801, Philippines, scale bar: 1.0 mm. G, Hypselodoris confetti Gosliner & Johnson sp. nov., holotype, CASIZ 191070, scale bar: 0.60 mm. H, Hypselodoris decorata (Risbec, 1928), CASIZ 184316, scale bar: 0.60 mm. am, ampulla; bc, bursa copulatrix; ej, ejaculatory portion of the vas deferens; fgm, female gland mass; p, penis; pr, prostatic portion of vas deferens; rs, receptaculum seminis; ud, uterine duct; v, vagina; vg, vestibular gland.

Figure 5. Hypselodoris brycei Gosliner & Johnson sp. nov., paratype, WAM S12628. A, jaw rodlets. B, inner lateral teeth. C, middle lateral teeth. D, outer lateral teeth.

Figure 35. Bayesian inference and maximum likelihood tree of Hypselodoris, indicating support values for each node. Bootstrap values are on the left and Bayesian posterior probablilities on the right.