Hypselodoris decorata, (RISBEC, 1928)

HYPSELODORIS DECORATA ( RISBEC, 1928) View in CoL

( FIGS 2D, 4H, 9, 10)

Chromodoris decorata Risbec, 1928: 152–154 View in CoL , fig. 43, pl. VII, fig. 4.

Hypselodoris maculosa View in CoL misidentification, not H. maculosa Pease, 1871 View in CoL ; Gosliner et al., 2015: 254, second photograph from top on left.

Material examined

CASIZ 191315 , subsampled for molecular study, Mizegwadan Reef , 5.16000°S, 145.82333°E, Madang, Papua New Guinea, 20 m depth, 18 November 2012 GoogleMaps , V. Knutson . CASIZ 191214 , two specimens, one dissected, south point, Pana Tibun islet, 5.196667°S, 145.806667°E, 14 November 2012 GoogleMaps , Anthony Berberian. CASIZ 190661 , one specimen, dissected, Bethlehem, 13.67°N, 120.84°E, Tingloy , Maricaban Island, Batangas, Luzon, Philippines, 17 November 2012 GoogleMaps , T. Gosliner . CASIZ 184316 , one specimen, dissected, Bethlehem, 13.67°N, 120.84°E, Tingloy , Maricaban Island, Batangas, Luzon, Philippines, 2 October 2010 GoogleMaps , T. Gosliner . CASIZ 208606 , one specimen, off Bamboo Beach 13.52°N, 120.96°E, Batangas Channel , Puerto Galera, Mindoro Oriental, Philippines, 11 April 2015 GoogleMaps , T. Gosliner . CASIZ 176776 , two specimens, West Beach , Pulau Tenggol, South China Sea, Malaysia, 29 September 2007 , T. Gosliner . CASIZ 197309 , one specimen, Calatagan 13.91°N, 120.60°E, Batangas, Luzon , Philippines, 19 May 2014 GoogleMaps , C. Piotrowski. CASIZ 217267 , one specimen, Bonito (Culebra) Island 13.63°N, 120.95°E, Tingloy , Batangas, Luzon, Philippines, 21 April 2016 GoogleMaps , T. Gosliner . CASIZ 217358 , two specimens, Dive and Trek reef, 13.80°N, 120.91°E, Bauan , Batangas, Luzon, Philippines, 17 April 2016 GoogleMaps , Brenna Green.

Type locality

New Caledonia.

Geographical distribution

Known from the Marshall Islands, Vanuatu, New Caledonia, Indonesia, Papua New Guinea, the Philippines and Malaysia (present study).

Description

External morphology: Living animals ( Fig. 9) moderately large, reaching 25 mm in length. Body long, slender, translucent pink, with four thin, continuous opaque white longitudinal lines on dorsal surface of notum. Broad orange band found along lateral margins of notum, often with interior undulations and opaque white spots.Anterior and posterior ends of the animal with purple to orange areas with opaque white spots. Rows of reddish to purple spots found on notum, with more diffuse purple pigment found around periphery situated between opaque white lines. Similar pattern of lines and spots found on lateral margins of the body and foot. Seven to eight unipinnate gill branches having a translucent white base and inner margin and bright red–orange pigment on apical surfaces and outer margin. Bulb of perfoliate rhinophores opaque white with two red transverse bands and bearing ~14–16 densely arranged lamellae. Base of rhinophores translucent white with a third red transverse ring.

Mantle glands: Subcutaneous mantle glands simple and rounded in shape ( Fig. 2D). Glands situated anteriorly and posteriorly, with no glands present in the central lateral regions of body margin. Eight to ten glands on either side of anterior end of the body, with arc of 15–20 glands situated posteriorly. Their arrangement was based upon four specimens examined.

Buccal armature: Muscular portion of buccal mass slightly longer than oral tube. Chitinous labial cuticle ( Fig. 10A) found at anterior end of muscular portion of the buccal mass bearing numerous jaw rodlets ( Fig.10B). Rodlets sharply angled with single, acutely pointed apex and posterolateral extensions. Radular formula of two specimens 55 × 26.0.26 ( CASIZ 190661) and 48 × 26.0.26 ( CASIZ 191214) ( Fig. 10C). Rachidian row of teeth absent ( Fig. 10D). Innermost lateral teeth having one or two large, triangular denticles on inner side of bifid primary cusp, with another one to two outer denticles. Next several laterals lacking inner triangular denticle but possessing two denticles on outer side of primary bifid cusps. Midlateral teeth ( Fig. 10E) all lacking inner denticles but having three to four sharply pointed, triangular outer denticles. Outermost teeth having a narrower base and shorter tooth shape, with two to four rounded outer denticles ( Fig. 10F).

Reproductive system: Reproductive organs ( Fig. 4H) fully mature in two specimens examined ( CASIZ 1908661, CASIZ 184316). Ampulla thick, tubular, 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 short, narrow, muscular ejaculatory portion. Ejaculatory portion widening into penial bulb. Penial bulb adjacent to curved, slightly wider 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 minute receptaculum seminis and larger spherical, thin-walled receptaculum seminis. Receptaculum situated near base of bursa. Moderately long uterine duct emerging from vagina close to base of bursa and female gland mass, near albumen gland.

Remarks

Hypselodoris decorata View in CoL is very similar to H. maculosa ( Pease, 1871) View in CoL and was regarded as a synonym of this species by Rudman (1986). Johnson (2005) suggested that H. decorata View in CoL has several distinguishing attributes of its colour pattern that separate it from H. maculosa View in CoL , including the presence of three rather than two red rhinophoral rings. Owing to this confusion, we have provided a complete description of H. decorata View in CoL for purposes of comparison with that described for H. maculosa View in CoL ( Rudman, 1986; Gosliner & Johnson, 1999). The fact that specimens identified here as H. maculosa View in CoL , with two rhinophoral rings, cluster together with species separate from H. decorata View in CoL (with three rhinophoral rings) in our molecular phylogeny gives credence to the observation by Johnson (2005) that these represent distinct species. Hypselodoris decorata View in CoL is sister to H. juniperae View in CoL sp. nov., described later in this study, and H. maculosa View in CoL . In addition to the colour differences noted by Johnson (2005), there appear to be distinct anatomical differences between the two species. In H. decorata View in CoL , posterior glands are present, but there are no anterolateral mantle glands, and anterior mantle glands may be present or absent. In H. maculosa View in CoL , posterior mantle glands are present, as are anterolateral and anterior glands. In H. decorata View in CoL , the middle lateral teeth possess fewer denticles (three or four), whereas those of H. maculosa View in CoL have four or five denticles ( Fig. 11). The reproductive system of H. decorata View in CoL has a very short ejaculatory segment of the vas deferens, whereas that of H. maculosa View in CoL has a much more elongate ejaculatory segment ( Fig. 4B). Also, the receptaculum seminis of H. decorata View in CoL is situated immediately below the bursa, whereas it is much closer to the uterine duct in H. maculosa View in CoL . Both species appear to be sympatric in the Marshall Islands, Papua New Guinea and the Philippines. Differences between this species and H. alburtuqali View in CoL and other members of H. maculosa View in CoL are detailed in the remarks section of H. alburtuqali View in CoL .