Tritomini, Curtis, 1834

Skelley, Paul E., 2020, Nomenclatural notes for the Erotylinae (Coleoptera: Erotylidae), Insecta Mundi 2020 (767), pp. 1-35 : 5-6

II. Tritomini : Triplax Herbst , Paratritoma Gorham , Tritomapara Alvarenga , Ogcotriplax Heller, Pseudotriplax Heller, Platichna Thomson.

Concern discovered. Generic synonymy based on transfer of type species with resulting incertae sedis, invalid type designation or proposed nomen nudum, and nomenclatural details of some subgeneric names.

Discussion and results. Multiple issues were discovered in the synonymy of Triplax Herbst, 1793 , which is a genus that is found in both the Old and New Worlds. These concerns are discussed individually in the following.

Paratritoma Gorham. The genus Paratritoma Gorham, 1888: 71 , was described for some colorful Central American species superficially similar to Tritoma Fabricius and Mycotretus Lacordaire in body shape and other general characters. Alvarenga (1965: 88) subsequently designated Paratritoma divisa Gorham, 1888 , as the type species for Paratritoma .

Johnson (1967) found Paratritoma morphologically similar to species of Triplax Herbst, 1793 , differing in color pattern and having similar but smaller pronotal angle pores. Johnson stated, “In other characters, such as the length to width ratio of the body, shape of the pronotum, development of the postmandibular lobes, and width of the terminal segments of the maxillary palpi with distinct apical brush, few significant differences have been found.” Johnson (1967: 8) then transferred the type species of Paratritoma , P. divisa Gorham ( Figure 4 ), to Triplax . By transferring the type species, he unknowingly synonymized Paratritoma with Triplax .

Alvarenga (1970: 45) recognized this synonymy and that all remaining species of Paratritoma were now considered incertae sedis. To correct this, he intended to propose a new genus, Tritomapara Alvarenga, 1970 , for these remaining species, designating Paratritoma dimidiata Gorham, 1888 , as the type species. Unfortunately, he stated “n. nov. (Pro Paratritoma Gorham, 1888 )”. Proposing a new name for a genus does not allow changing of the type species (ICZN 1999, Article 67.8). Thus, the type species of Tritomapara (= Paratritoma ) is P. divisa , which makes the designation of P. dimidiata as the type species Tritomapara invalid. Having the same type species, Paratritoma and Tritomapara are objective synonyms.

Even if Alvarenga (1970) had stated “n. nov. (Pro remaining species of Paratritoma Gorham, 1888 )” he presented no description of the genus. Under the ICZN (1999, Article 13.1.1), Tritomapara Alvarenga (1970, 1994 ) is a nomen nudum and unavailable. Alvarenga’s (1994) catalog listed Tritomapara and all included species, again without a description. In both instances, as a nomen novum or a nomen nudum, Tritomapara can not be used as Alvarenga intended.

Species of “ Paratritoma ”. In spite of Alvarenga’s efforts, the remaining species of Paratritoma remain incertae sedis. Types of six species of Paratritoma and specimens of other species ascribed to this genus have been studied. The holotype of P. dimidiata and most other holotypes possess characters as outlined by Johnson (1967) that would place them in Triplax : characters include large umbilicate pronotal pores and dilated terminal maxillary palpomeres with an apical brush. Two species I have not studied, Paratritoma brasiliensis Guérin, 1946 , and Paratritoma melanoderes Kuhnt, 1910 , were examined by Italo Pecci-Maddalena (pers. comm.). He found they lacked a true brush on the apical maxillary palpomere, which makes their placement in this group questionable.

To resolve their incertae sedis status, all species of the Neotropical genus Paratritoma Gorham (= Tritomapara Alvarenga ) are provisionally transferred to Triplax , pending further comprehensive studies. The corrected synonymy below reflects these new combinations.

Ogcotriplax Heller and Pseudotriplax Heller. The Old-World synonyms of Triplax require clarification. Ogcotriplax Heller, 1920: 29, and Pseudotriplax Heller, 1920: 29, were both proposed as subgenera of Triplax . Since their original description, they have only been mentioned as subgenera by Chûjô (1969: 174–175) as a note in his key to species and the catalog of Chûjô and Chûjô (1990: 10) as subgenera under Triplax . However, neither of these works assigned species to these subgenera. Thus, Wegrzynowicz’s (2007: 543) catalog was the first work to present these as full synonyms of Triplax . Until more comprehensive studies are published, I agree with these synonymies.

Platichna Thomson. Finally, Platichna Thomson, 1863: 295, was described with two European species, Triplax bicolor ( Marsham, 1802: 122) [a junior synonym of Triplax aenea ( Schaller, 1783: 254) ] and Triplax rufipes ( Fabricius, 1787: 222) , without designating a type species. Ganglbauer (1899: 639–645) and Jakobson (1915: 934) treated Platichna as a subgenus, recognizing “ Triplax (Triplax) aenea (Schaller) ” [with T. bicolor Marsham as a synonym] and “ Triplax (Platichna) rufipes (Fabricius) ”. However, Kuhnt (1909: 81, 1911: 59) fully synonymized Platichna and the misspelling “ Platychna ” under Triplax . Subsequently, with “ Platychna ” treated as a synonym of Triplax, Iablokov-Khnzorian (1975: 224) designated T. aenea as the type species of Platichna, which was followed by Chûjô and Chûjô (1990: 9). The synonymical relationship of Triplax aenea and T. bicolor was not recognized by Iablokov-Khnzorian (1975) but was recognized by Chûjô and Chûjô (1990). None of these authors recognized that T. aene a (= T. bicolor ) had been removed from Platichna by Ganglbauer (1899) and Jakobson (1915). More recently, Wegrzynowicz (2007: 543), without explanation, cited T. rufipes as the type species of Platichna.

The first designation for the type species of Platichna by Iablokov-Khnzorian (1975: 224) lists only T. aenea , but not T. bicolor as a synonym, and T. aenea was not an originally included species. According to the ICZN (1999) Article 69.2.2, “If an author designates as type species a nominal species that was not originally included (or accepts another’s such designation) and if, but only if, at the same time he or she places that nominal species in synonymy with one and only one of the originally included species (as defined in Article 67.2), that act constitutes fixation of the latter species as type species of the nominal genus or subgenus.” Thus, Iablokov-Khnzorian’s designation of T. aenea , which did not list the synonym T. bicolor , is invalid.

The second designation for a type species of Platichna was by Chûjô and Chûjô (1990: 9), who listed the type as T. bicolor . Even with T. aenea being removed from Platichna, ICZN (1999), Article 69.1.1., states “In the absence of a prior type fixation for a nominal genus or subgenus, an author is deemed to have designated one of the originally included nominal species as type species, if he or she states (for whatever reason, right or wrong) that it is the type or type species, or uses an equivalent term, and if it is clear that that author accepts it as the type species.” Thus, right or wrong, the 1990 designation by Chûjô and Chûjô must be considered valid. The subsequent designation by Wegrzynowicz (2007: 543) was unnecessary and invalid.

Figures

Figure 3–4. Types of species in “Paratritoma” Gorham, dorsal and ventral habitus with labels.3) Triplax dimidiata (Gorham), NHMUK. 4) Triplax divisa (Gorham), NHMUK.