Tycheinae

Nieto, Juan M., Hidalgo, Nicolás Pérez & Durante, Pilar Mier, 2007, New synonyms and several nomenclatural clarifications on family-group names in the Aphididae (Hemiptera Sternorrhyncha), Zootaxa 1629, pp. 51-55 : 52-53

Is Tycheinae an aphid taxon?

Koch (1857) described the genus Tychea and two species: Tychea graminis (pages 298-299, figures 365, 366a, 366b) and Tychea amycli (page 300, figure 367). The descriptions and illustrations are not detailed enough to clearly indicate which species the author was referring to. As the studied material was not kept (i.e. there is now no type material), we can only be sure of this by designating the neotype of each species. However, it is evident that Koch had described and illustrated coccids (figures 365, 366a) and aphids in the genus Geoica Hart, 1894 (figure 366b), but using the name T. graminis . He described some aphids, possibly also in the genus Geoica , using the name T. amycli . We now know that several species of coccids, and aphids belonging to the tribe Fordini , other tribes of Eriosomatinae or Anoeciinae coexist in the nests of aphidophilous ants: however, Koch (1857) believed that all the specimens collected together belonged to the same species, which is an understandable error, given the level of knowledge of aphids at that time.

Three years later, Passerini (1860) described five species (also radicicolous) of the genus Tychea : T. setulosa (currently Geoica setulosa ), T. phaseoli (junior synonym of Smynthurodes betae Westwood, 1849 ), T. trivialis (junior synonym of Forda marginata Koch, 1857 ), T. eragostidis and T. setariae (both are in the group utricularia of the genus Geoica and possibly synonyms of some other species in this group ( Remaudière & Remaudière 1997). Undoubtedly, Passerini (i) attributed the genus to Koch, (ii) did not mention either of the two species of Koch because his study dealt with Italian aphids and Koch’s species were German, (iii) did not intend to describe a new genus (Passerini clearly indicated his own taxa, and article 65.1 of the I.C.Z.N. must be applied, (iv) established the species type of the genus in an invalid nomenclatural act because the type-species should have been one of the two species of Koch and not Tychea phaseoli .

Passerini (1862) attributed again these five species to “ Tychea Koch ” and established the tribe Tycheinae exclusively for this genus.

Wilson (1910) validly designated Tychea graminis as the type-species, without adding any explanations or comments.

Börner (1930) corroborated the type-species established by Wilson, as have subsequent aphidologists, and established the synonomy between Tychea phaseoli Passerini, 1860 (now Smynthurodes betae Westwood ) and T. graminis Koch, 1857 . This has not be accepted by other authors as the viviparous apterous female (fig. 366b) in the description by Koch is not Smynthurodes betae . We are agree with this last opinion, because Koch illustrated an aphid as green-coloured, with short antennae and without long conspicuous setae on the body and appendages, but S. betae is dirty yellowish white-coloured and wax-dusted in life, it has more large antennae and long and conspicuous setae.

Eastop & Hille Ris Lambers (1976) stated that (i) Tychea Koch, 1857 (Type-species Tychea graminis Koch, 1857 ) is a coccid but they forgot that Koch described and illustrated both aphids and coccids under this taxon name, (ii) Tychea amycli Koch, 1857 is nomen dubium, (iii) there is a genus Tychea Passerini (junior homonym of Tychea Koch , type-species Tychea phaseoli Passerini, 1859 (= Smynthurodes betae Westwood, 1849 ), and junior synonym of Smynthurodes Westwood, 1849 ). But as has been demonstrated there is no such genus of Passerini and neither can it be stated that T. graminis is a coccid or an aphid while its neotype is not designated. For the moment it is regarded as a coccid and, at the same time, an aphid, in other words, it is nomen dubium!

Remaudière & Remaudière (1997) (i) followed what was indicated by Eastop & Hille Ris Lambers (1976), (ii) placed Tychea Passerini amongst the synonyms of Smynthurodes Westwood , (iii) included Tychea Koch (Coccoidea) in the unavailable genera. This is not nomenclaturally correct, though, and in fact the name should not be used because its taxomonic significance is not clear.

Nieto Nafría et al. (1998b) also sustained the existence of Tychea Passerini as a junior homonym of Tychea Koch and thus [I.C.N.Z. article 39] consider Tycheinae Passerini as an unavailable name.

Nieto Nafría et al. (2003) maintained that Tycheinae Passerini was invalid, though they wrote « Tychea Koch, 1857 sensu Passerini, 1860 (mistaken identity)» in the list of synonyms of Smynthurodes . We cannot actually say whether Passerini was mistaken in his generic identification of the observed specimens or whether his taxonomical of Tychea concept was correct. In any case, this discrepancy does not affect the point in question because Passerini not established a new genus named Tychea .

In conclusion: (1) the type genus of Tycheinae Passerini is Tychea Koch and is not the “non-existent” Tychea Passerini , (2) Tychea Koch is nomen dubium and not necessarily only a coccid or only an aphid, and (3) Tycheinae Passerini is an available name, but also nomen dubium referring to either coccids or aphids.