A stomach plate to divide them all: a phylogenetic reassessment of the family Tritoniidae (Nudibranchia: Cladobranchia) Author Silva, Felipe De Vasconcelos Departamento de Biología, Facultad de Ciencias del Mar y Ambientales; Universidad de Cádiz; Campus de Excelencia Internacional del Mar (CEI · MAR), Av. República Saharaui, s / n, Ap. 40. 11510 Puerto Real (Cádiz), Spain felipe.devasconcelos@uca.es Author Pola, Marta Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid; Campus de Excelencia Internacional UAM + CSIC, C / Darwin, 2, 28049 Madrid, Spain Author Cervera, Juan Lucas Departamento de Biología, Facultad de Ciencias del Mar y Ambientales; Universidad de Cádiz; Campus de Excelencia Internacional del Mar (CEI · MAR), Av. República Saharaui, s / n, Ap. 40. 11510 Puerto Real (Cádiz), Spain & Instituto Universitario de Investigación Marina (INMAR), Universidad de Cádiz; Campus de Excelencia Internacional del Mar (CEI · MAR), Universidad de Cádiz, Av. República Saharaui, s / n, Ap. 40. 11510 Puerto Real (Cádiz), Spain text Zoological Journal of the Linnean Society 2023 Zool. J. Linn. Soc. 2023-07-11 199 2 445 476 http://dx.doi.org/10.1093/zoolinnean/zlad013 journal article 10.1093/zoolinnean/zlad013 0024-4082 C3E2DFF9-A0A6-41EA-A149-0F73A2BEE5E6 Subfamily Tritoniinae Lamarck, 1809 Zoobank registration: urn:lsid:zoobank.org:act: 1EE29562- 18DF-41B2-920F-412511CFC43C . Diagnosis: True stomach plates absent. ODG complex holohepatic. Genera included in this study: Tritonia , Candiella (see diagnosis below), Marianina , Myrella (see diagnosis below), Tochuina , Tritonicula , Tritonidoxa , Tritoniella and Tritoniopsis . Figure 6. Reproductive system arrangements of analysed key species of Tritoniinae and Marioniinae subfam. nov. , dorsal view: A, Tritonia hombergii (ZMBN 83471); B, Candiella plebeia (ZMBN 83471); C, Tritoniopsis flydis (GR7-DMC00040); D, Tritonidoxa capensis (MNCN15.05/93399); E, Tochuina gigantea (NHMD-115967); F, Tritonicula hamnerorum (MNCN15.05/93378); G, Marionia blainvillea (NHMD115968). Abbreviations: ag, albumen gland; am, ampulla; bc, bursa copulatrix; fo, female opening; fgm, female gland mass; hd, hermaphrodite duct; o, oviduct; p, penis; pp, prostatic portion; ps, penial sheath; v, vagina; vd, vas deferens. Table 2. Summary of morphological diagnostic characters of Tritoniidae . Geographic distribution abbreviations: AO: Atlantic Ocean; IO: Indian Ocean; M: Mediterranean Sea; SO, Southern Ocean; PO: Pacific Ocean
Subfamily Tritoniinae
Genera Tritonia Candiella Tritoniopsis Tritonidoxa Tritoniella Marianina
Size (mm) 17–300 8–34 17–100 25–32 80 20
Oral veil Bilobed Entire Bilobed or entire Entire Bilobed Entire
Velarpro- 7–40 4–8 9–13, alternated in 8 6–16 (when 4
cesses size present)
Pairs of gills ≥7 2–16 14–20 Absent Absent 3–7
Masticatory Denticulate Denticulate Differentiated or Denticulate Denticulate Denticulate
border smooth
Rachidian Uni- or tricuspid, Tricuspid and smooth Unicuspid and den- Tricuspid Uni- or Unicuspid
tooth smooth or den- ticulate and smooth tricuspid, and denticu-
ticulate smooth or late
denticulate
Inner lateral Differentiated Differentiated and denUndifferentiated, usu- Differen- Un– or dif-
Differentitooth and smooth ticulate (single denticle) ally denticulate tiated and ferentiated, ated and fully
smooth smooth or denticulate
denticulate
Outer lateral Numerous, up Several, up to 50 Few, up to 10 Several, up Several, up Few, up to 5
teeth (per to 200 to 72 to 98
half row)
Stomach Cuticular folds Absent Absent Absent Cuticular Cuticular
cuticle in some species folds folds
ODG Holohepatic Holohepatic Holohepatic Holohepatic Holohepatic Cladohepatic
complex
Geographic AO, IO, M, PO AO, M AO, IO, PO AO SO IO, PO
distribution
References Macfarland Haefelfinger (1963) ; Eliot (1905) ; Er. Bergh Bergh Pruvot–Fol
(1966); Ev. Marcus (1983) ; Marcus and Ev. Mar- (1907); pre- (1907); pre- (1930);
Korshunova Schmekel and Portmann, cus (1970); Yonow sent study sent study Odhner
and Martynov (1982); present study (2017); present study (1936)
(2020); present
study
Subfamily Tritoniinae Marioniinae subfam. nov.
Genera Myrella Tochuina Tritonicula Marionia Marioniopsis Paratritonia
Size (mm) 18–80 82–300 7–16 6–200 17–88 20–35
Oral veil Entire or bilobed Entire Entire Bilobed Bilobed Entire
Velar processes 5–20 8–9 (when present) 4–6 4–18 3–7 6
Pairs of gills 6–40 Numerous 7–15 5–16 7–100 6–7
Masticatory Denticulate Smooth Denticulate Denticulate Denticulate or Denticulate
border differentiated
Rachidian Tricuspid and Unicuspid, smooth or den- Tricuspid and smooth Tricuspid and Tricuspid and Unicuspid
tooth denticulate ticulate smooth denticulate and
denticulate
Inner lateral Differentiated and Slightly differentiated and Differentiated and Differentiated Differentiated
Differentooth smooth smooth denticulate (several dent- and smooth and smooth tiated and
icles) smooth
Outer Numerous, up to Numerous, up to 312 Few, oħen up to 12 Few to numer- Few to numer- Numerous,
lateral teeth 115 ous, up to 120 ous, up to 135 up to 110
(per half row)
Stomach cuticle Absent Cuticular folds Absent Stomach plates Stomach plates Stomach
plates
ODG Holohepatic Holohepatic Holohepatic Cladohepatic Clado– or Holohepatic
complex holohepatic
Table 2. Continued
Subfamily Tritoniinae Marioniinae subfam. nov.
Genera Myrella Tochuina Tritonicula Marionia Marioniopsis Paratritonia
Geographic SO PO PO, AO AO, PO, M AO, IO, PO PO
distribution
References Wägele (1995) ; MacFarland (1966) ; Korshunova and Silva et Avila et al . Baba (1949)
Schrödl (2003) ; Korshunova and Martynov (2020); al . (2013, (1999);
Ballesteros and Martynov (2020); pre- present study 2019); Smith and
Avila (2006); sent study present Gosliner
Rossi et al . study (2007); pre-
(2021) sent study
Remarks: The absence of true stomach plates is considered a plesiomorphy within Tritoniidae , according to the basal position of Pleurobranchidae in our phylogenetic analyses. The term ‘true stomach plates’ is used in this study to differ these structures from other type of cuticular structure, homologous to the stomach plates of marioniids, known as cuticular folds. Cuticular folds are longitudinal folds covered by a thin cuticular layer derived from the cuticular lining of the stomach. Unlike stomach plates, the cuticular folds have a single continuous cuticular layer along their entire length and are not individually detachable ( MacFarland 1966 ). These structures are present in Tochuina ( MacFarland 1966 ) , Tritoniella ( Wägele 1989 ) , Marianina ( Odhner 1963 ) , Tritonia festiva ( MacFarland 1966 ) , Tritonia exsulans ( MacFarland 1966 ) and Tritonia odhneri Er. Marcus, 1959 ( Schrödl 2003 ).