Trapania franae, Paz-Sedano & Cobb & Gosliner & Pola, 2024

Paz-Sedano, Sofia, Cobb, Gary, Gosliner, Terrence M. & Pola, Marta, 2024, Filling gaps in the knowledge of Goniodorididae taxa (Mollusca, Gastropoda, Nudibranchia) with description of seven new species, Zootaxa 5443 (4), pp. 523-547 : 525-528

Trapania franae sp. nov.

( Figs. 1A , 2A‒B , 3A‒F )

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Trapania sp. 4 — Cobb (2019)

Trapania spB.— Paz-Sedano et al. (2024) Type material. Holotype: QM MO 86031 , La Balsa Park , Mooloolah River, Queensland, Australia, 1–5 m depth, 20 September 2020, col. by G. Cobb, 96% EtOH, dissected and sequenced ( SEM: radula, labial cuticle).

External morphology ( Fig. 1A ). Preserved specimen 8 mm in length, live up to 15 mm. Body elongated, cylindrical, without developed notal border. Anterior part of head and end of foot rounded. Two extra-rhinophoral appendages, one near base of each rhinophore, short, wide, with apex curved backwards. Two extra-branchial appendages, one on each side of gill. Extra-branchial appendages similar in shape to extra-rhinophoral appendages, slightly larger. Rhinophores nonretractile, elongated, slender, bearing 12–13 lamellae each. Lamellae oriented posteriorly. Tips of rhinophores thin and smooth. Rhinophoral sheaths absent. Gill composed of three plumose branches forming a semicircle around anus, one gill branch located on middorsal part of body, one on each side. One digitiform and elongated oral tentacle on each side of mouth. Reproductive opening located on right lateral side, in first third of body.

Color pattern ( Fig. 1A ). Body opaque white with large dark brown patches covering most of body, including oral tentacles, rhinophores and extra-rhinophoral and extra-branchial appendages. Gill branches hyaline white with opaque white spots.

Foregut anatomy ( Figs. 2A , 3A‒E ). Buccal bulb thick and muscular ( Fig. 2A ). Muscular oral tube surrounds lips anteriorly. Small and flat buccal pump located dorsally. Small radular sac located ventrally. Esophagus begins from buccal bulb behind buccal pump. Salivary glands very small, rounded, located at junction of esophagus with buccal bulb. Nervous system covers this junction. Esophagus continues posteriorly and inserts into digestive-hermaphroditic gland. Labial cuticle surrounds lips and expands within buccal pump. Surrounding lips, labial cuticle armed with pointed jaw elements ( Fig. 3A ). Radular formula 19 × 1.0.1. Five to eight outermost denticles very small, pointed, followed by largest and widest cusp ( Figs. 3B‒E ). Inner side of largest cusp with 8–11 strong denticles. Shape and size of inner denticles vary slightly. Denticles become smaller towards the inner part, one additional large denticle may be present after one or two smaller denticles ( Fig. 3D ). A third variation may be alternative larger with smaller denticles ( Figs. 3C, E ).

Reproductive system ( Figs. 2B , 3F ). Reproductive system located in anterior third of body. Thin hermaphroditic duct begins at ovotestis, located inside digestive-hermaphroditic gland. Hermaphroditic duct expands into very large and oval ampulla. Postampullary duct emerges from ampulla and divides into short oviduct and elongate vas deferens. Short oviduct enters inside female gland mass. Vas deferens connects with first portion of prostate. Prostate large, sausage-shape. Prostate surrounds ampulla and continues with slightly narrower vas deferens. Vas deferens with similar width to prostate. Vas deferens continues and expands to ejaculatory duct. Penis with small, hooked penial spines ( Fig. 3F ). Vagina thin and elongate, around half width than vas deferens. Vagina connects with small, rounded bursa copulatrix. At base of bursa copulatrix, emerges an elongate duct that joins with a small and rounded receptaculum seminis. From base of receptaculum seminis arises a thin uterine duct that enters female gland mass. Size of receptaculum seminis similar to bursa copulatrix.

Etymology. The species is named for Fran Roberts, who first found Trapania franae in the river estuary.

Distribution. Australia, Queensland, Mooloolah River, La Balsa Park and Moreton Island ( Cobb 2019; present study).

Natural history. The species has been found on silty, sandy substrates and rocks up to 6 m deep.

Remarks. Among Trapania species that inhabit the Indo-Pacific Ocean, the most similar species to Trapania franae sp. nov. are T. japonica ( Baba, 1935) , T. naeva Gosliner & Fahey, 2008 and T. tamaraw Smirnoff, Donohoo & Gosliner, 2022 . The four species share a color pattern with light background, white or yellow-tan color, and dark spots along the body ( Baba 1935; Gosliner & Fahey 2008; Smirnoff et al. 2022). However, they also show several morphological and anatomical differences. Trapania japonica has bright yellow appendages, while T. franae sp. nov. lacks them. Moreover, T. franae sp. nov. has translucent white gill branches while in T. japonica and T. naeva they are dark ( Baba 1935; Gosliner & Fahey 2008). The dark patches of T. franae sp. nov. and T. tamaraw are larger and more numerous than in T. japonica and T. naeva ( Baba 1935; Gosliner & Fahey 2008). Regarding the radula, T. japonica and T. franae sp. nov. have denticles in the outer side of the largest cusp while T. naeva and T. tamaraw lack them ( Baba 1935; Gosliner & Fahey 2008; Smirnoff et al. 2022). In T. japonica , the outer denticles of the radula are much larger than in T. franae sp. nov. In T. tamaraw , these denticles are smaller, similar in size and shape than in T. franae sp. nov. Also, they are more numerous in T. japonica than in T. franae sp. nov. ( Baba 1935; Smirnoff et al. 2022). Regarding the reproductive system, the duct that connects the bursa copulatrix and the receptaculum seminis in T. japonica and in T. tamaraw is notably smaller than the duct of T. franae sp. nov. ( Smirnoff et al. 2022). The bursa copulatrix also varies between T. franae sp. nov. and T. naeva , being rounded or thin walled, respectively ( Gosliner & Fahey 2008). Moreover, the four species were included in the phylogenetic analyses of Paz-Sedano et al. (2024), which supported the separation of them.

Figures

FIGURE 1. Living animals. A. Trapania franae sp. nov. (QM MO 86031). B‒C. Bermudella lahainensis sp. nov., B. CASIZ 180297 and C. CASIZ 192539; D. Bermudella mica. E. Ceratodoris plebeia (MNCN 15.05/94478). F‒G. Ceratodoris trypomandyas sp. nov., F. QM MO 86033 and G. AM C. 270712. H. Murphydoris polkadotsa sp. nov. (QM MO 86038). (Photos A, F–H by G. Cobb., B‒C by C. Pittman, D by P. Pérez, E by S. T. Huang)

FIGURE 2. Buccal bulb and reproductive system. A‒B. Trapania franae sp. nov. (QM MO 86031), A. Buccal bulb. B. Reproductive system. C‒D. Bermudella lahainensis sp. nov. (CASIZ 199240). C. Buccal bulb. D. Reproductive system. E‒F. Bermudella mica (MNCN 15.05/94474). E. Buccal bulb. F. Reproductive system. G–H. Bermudella plebeia (MNCN 15.05/94477). G. Buccal bulb. H. Reproductive system. I‒J. Ceratodoris trypomandyas sp. nov. (QM MO 86034). I. Buccal bulb. J. Reproductive system. Abbreviations: am, ampulla; bc, bursa copulatrix; bp, buccal pump; fgm, female gland mass; hd, hermaphroditic duct; oe, esophagus; op, esophageal pump; p, penis; pr, prostate; ra, radular sac; rs, receptaculum seminis; sgl, salivary gland; ud, uterine duct; va, vagina; vd, vas deferens. Scale bars: 1 mm.

FIGURE 3. Scanning electron micrographs and light microscope photographs of cuticles, radulae, and penis. A‒F. Trapania franae sp. nov. (QM MO 86031). A. Detail of jaws. B. Frontal view of radula. C‒E. Detail of denticles of the tooth. F. Detail of penial spines. G‒J. Bermudella lahainensis sp. nov. G. Frontal view of the radula (CASIZ 119240). H. Frontal view of half radula (CASIZ 192539). I. Detail of inner and outer lateral teeth (CASIZ 192539). J. Detail of outer lateral teeth (CASIZ 119240). Scale bars: A, B, G: 20 μm; C, H, J: 20 μm; D‒F, I: 10 μm.