Phestilla subodiosus, Wang & Conti-Jerpe & Richards & Baker, 2020

Wang, Adam, Conti-Jerpe, Inga Elizabeth, Richards, John Lawrence & Baker, David Michael, 2020, Phestilla subodiosus sp. nov. (Nudibranchia, Trinchesiidae), a corallivorous pest species in the aquarium trade, ZooKeys 909, pp. 1-24 : 1

publication ID	https://dx.doi.org/10.3897/zookeys.909.35278
publication LSID	lsid:zoobank.org:pub:202D2B19-4952-431D-A076-80D6110971CA
persistent identifier	https://treatment.plazi.org/id/F5F4BF04-1295-4A66-87F9-F09BC61590EB
taxon LSID	lsid:zoobank.org:act:F5F4BF04-1295-4A66-87F9-F09BC61590EB
treatment provided by	ZooKeys by Pensoft
scientific name	Phestilla subodiosus
status	sp. nov.

Treatment

Phestilla subodiosus sp. nov. Figures 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Tenellia sp. L: Cella et al. 2016: 9, 14, fig. 2, table 5 (locality unlisted).

Tenellia sp.: Cho et al. 2018: GenBank Accession number MG878397 (Jeju Island, South Korea).

Type Material.

Holotype: [SWIMS-MOL-17-001]. 1 specimen 2 mm long in 95% ethanol, dissected, Hong Kong SAR: Montipora spp., cultured in aquaria, coll. A. Wang, 19 Nov. 2017 (Figs 4a, b View Figure 4 , 5c View Figure 5 ).

Paratypes: [SWIMS-MOL-17-002]. 1 egg case 1 mm long in 95% ethanol. Hong Kong SAR: Montipora spp., cultured in aquaria, coll. A. Wang, 25 Nov. 2017 (Figs 2c View Figure 2 , 4c View Figure 4 ).[SWIMS-MOL-18-001]. 1 specimen 1.2 mm long in 95% ethanol. Hong Kong SAR: Montipora spp., cultured in aquaria, coll. A. Wang, 8 Mar. 2018 (live specimen in Fig. 1 View Figure 1 ). [SWIMS-MOL-19-008]. 1 specimen 3.0 mm long in 95% ethanol, dissected, Thailand: Koh Tao, Taa Chaa, depth 5 m, coll. R. Mehrotra, 22 Apr. 2019 (Fig. 5b View Figure 5 ) [SWIMS-MOL-17-003]. DNA extract from whole specimen 4mm long in 100% ethanol. Hong Kong SAR: Montipora spp., cultured in aquaria, coll. A. Wang, 19 Nov. 2017 (Fig. 2a View Figure 2 ) [SWIMS-MOL-18-002], [SWIMS-MOL-18-003], [SWIMS-MOL-18-004], [SWIMS-MOL-18-005], [SWIMS-MOL-18-006], [SWIMS-MOL-18-007]. DNA extracts from whole specimens 1-3.5 mm long in 100% ethanol. GenBank, respectively, Hong Kong SAR: Montipora spp., cultured in aquaria, coll. A. Wang, 8 Mar. 2018 (live specimens in Fig. 1 View Figure 1 ).

Etymology.

The specific epithet, subodiosus , Latin for odious and vexatious, is symbolic of its status as a pest in the aquarium trade, and also a homage to the time and prized Montipora colonies the first author lost to in an outbreak of this species.

Distribution.

Specimen collected from Koh Tao, Thailand (this paper). Reported from Jeju Island, Korea ( Cho et al. 2018 as Tenellia sp.) and confirmed using molecular methods. A similar species reported from Singapore according to a personal communication with Harris published by Robertson (1987: 3), unconfirmed. The type locality of the material from Cella et al. (2016) was not listed.

Description.

External morphology (Figs 1 View Figure 1 , 2 View Figure 2 , 4 View Figure 4 ). Thin elongate body. Sexually mature adults 1.5 mm to 4 mm in length, 0.5 mm to 1 mm in width. Oral tentacles connected to oral veil arising from edge approximately under rhinophores, brown band near the distal third. Rhinophores rounded distally, not distinct and lacking lamellae, with brown band near middle. Oral tentacles and rhinophores approximately same length. Eyes slightly posterior to each rhinophore. Body lacking obvious rhinophoral sheaths. First ceratal row slightly posterior to rhinophores. Fully developed rows contain three cerata. Cerata unbranching and arranged regularly in sloping transverse rows with two to three rows adjoining pericardium. One to three rows of cerata anterior to pericardium with no precardiac rows. Cerata lacking cnidosacs and always swollen terminally. Two to three additional swollen bulbs on fully developed cerata (Fig. 2 View Figure 2 ). Pericardium hump thick in relation to rest of body, nearly 1 mm thick, beginning at first cerata row and ending between second and third row (Fig. 2 View Figure 2 ). Body tapers strongly in thickness (<< 1 mm) after pericardium hump. Gonopore below and anterior to first cerata row, approx. at same height as the second cerata on the first row. Mouth large, diameter nearly equal to width of body, and clearly separated from foot.

Internal morphology (Fig. 5 View Figure 5 ). Jaws translucent and thin, smaller than 0.5 mm in 3 mm individual. Radular formula 12 × 0.1.0 in 3 mm individual, uniseriate. Teeth with central cusp and five to seven denticles on each side. Denticles and cusp arranged on curved edge. All denticles approx. same length. Central cusp longer and reaching slightly further than innermost denticles. Lacking secondary denticles. Reproductive system diaulic and spread throughout body. Penile bulb curved, connected to genital opening by short prostate, and adheres to wall of nudibranch. Female gland mass diameter 1.5 times size of penile bulb. Ampulla long and winding, diameter slightly larger than that of penile bulb, connected to vagina and appressed onto female gland mass, leading to hermaphrodite system. Lacks vas deferens. Penile bulb, female gland mass, and ampulla 0.5 mm to 1 mm combined.

Color. Two ontogenetic color forms. Juvenile animals with white epidermal pigment throughout entire body. Adults with white epidermal pigment and translucent ceratal epidermis. Cerata speckled with brown clots, possibly from internal fluids or dinoflagellates of Symbiodiniaceae from coral hosts. Swollen regions on cerata lack speckles. Speckle density decreases towards the posterior of the cerata.

Defense mechanisms. Cerata observed to autotomize and secrete viscous adhesive mucus, usually encapsulating abscised ceras, when animal is disturbed tacitly.

Observed prey items. Preys on coral species in the genus Montipora . Does not feed on corals of genera Porites , Acropora , and Echinophyllia . Reports of feeding on corals in genus Anacropora ( Henschen 2018), a sister genus to Montipora ( Fukami et al. 2000); however, this observation is unconfirmed by the authors.