Tritonicula Korshunova and Martynov 2020

Silva, Felipe De Vasconcelos, Pola, Marta & Cervera, Juan Lucas, 2023, A stomach plate to divide them all: a phylogenetic reassessment of the family Tritoniidae (Nudibranchia: Cladobranchia), Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 199 (2), pp. 445-476 : 467

publication ID	https://doi.org/ 10.1093/zoolinnean/zlad013
publication LSID	lsid:zoobank.org:pub:C3E2DFF9-A0A6-41EA-A149-0F73A2BEE5E6
DOI	https://doi.org/10.5281/zenodo.8432421
persistent identifier	https://treatment.plazi.org/id/03A6878C-FF86-6501-FC8C-FCA9EB19FC13
treatment provided by	Plazi
scientific name	Tritonicula Korshunova and Martynov 2020
status

Treatment

Tritonicula Korshunova and Martynov 2020 View in CoL

( Figs 3I View Figure 3 , 4F View Figure 4 , 5F View Figure 5 , 6F View Figure 6 )

Type species: Tritonicula hamnerorum ( Gosliner and Ghiselin 1987) View in CoL , by original designation.

Diagnosis: Appendage whitish at the edge of the rhinophore sheath. Series of accessory denticles on the first lateral tooth. Prostatic part of vas deferens conspicuous, located at the proximal end of the penial sheath.

Morphology: Body slender, up to 16 mm ( Fig. 3I View Figure 3 ). Notum smooth. Oral veil narrow and entire. Four to six simple velar processes, with the outermost ones oħen longer. Seven to 15 pairs of arborescent or poorly arborescent gills. Rhinophore sheath with whitish digitiform appendage on the rim. Ratio jaw/body length: 0.08–0.15. Rachidian tooth tricuspid and smooth ( Fig. 4F View Figure 4 ). First lateral tooth bearing five to 12 accessory denticles in the upper region ( Fig. 4F View Figure 4 ). Masticatory border of jaws denticulate; with medium-sized (up to 40 µm) denticles with conical bases and sharp cusps. Cuticular folds absent. ODG complex holohepatic ( Fig. 5F View Figure 5 ). Gonopore at end of one-third of body length, close to rhinophores. Anus and nephroproct at middle of body length. Conspicuous prostatic portion at the proximal end of penial sheath ( Fig. 6F View Figure 6 ). Bursa copulatrix connects to the female opening through the vagina and opens to the exterior together with the female mass gland ( Fig. 6F View Figure 6 ). Penis conical or flagelliform. Ampulla oħen fusiform and short ( Fig. 6F View Figure 6 ).

Species composition: Tritonicula bayeri , Tritonicula hamnerorum , Tritonicula ingolfiana ( Bergh 1899) comb. nov., Tritonicula khaleesi , Tritonicula myrakeenae (Bertsch and Osuna 1986) , Tritonicula pickensi and Tritonicula wellsi .

Remarks: The whitish appendage on the rhinophore sheath of Tritoniopsis was first noted in the re-description of Tritonicula wellsi and it is considered an adapted gill (Er. Marcus 1961, Schmekel and Portmann 1982). The number of accessory denticles on the first lateral tooth varies among species, and are also present in the second lateral tooth in Tritonicula bayeri (Ev. Marcus and Er. Marcus 1967) . The phylogenetic position of the species Tritonicula wellsi and Tritonicula khaleesi , both originally described as ‘ Tritonia ’ (Er. Marcus 1961, Silva et al. 2014), is molecularly confirmed in Tritonicula by our phylogenetic analyses ( Fig. 2 View Figure 2 ). Tritonicula khaleesi was previously transferred to the Pacific genus Marianina on the basis of similar radular and paedomorphic external morphology ( Korshunova and Martynov 2020) and subsequently transferred to Tritonicula together with Tritonicula wellsi based on the fleshy extension of the rhinophoral sheath ( Moles et al. 2021). Classification of the South Atlantic Tritonicula khaleesi based on morphological characters is particularly challenging because its radular morphology, characterized by rachidian tooth unicuspid, fully denticulate and without accessory denticles on the first lateral tooth, is not found in other tritoniids. We have also extended the reported distribution of Tritonicula khaleesi from Brazil, south-western Atlantic ( Silva et al. 2013) to Costa Rica (northwestern Atlantic), based on the specimen (voucher number MZUCR8300) previously identified as ‘ Tritonia ’ cf. pickensi in Camacho-García et al. (2014). The deep-sea Atlantic Tritonicula ingolfiana , which has not been studied molecularly, is included based on the poorly arborescent secondary gills, whitish appendage on the rhinophore sheath and accessory denticles on the first lateral tooth ( Bergh 1899).