Eukoenenia audax, Souza & Mayoral & Ferreira, 2020

Souza, Maysa F. V. R., Mayoral, Jaime & Ferreira, Rodrigo L., 2020, A new troglobitic palpigrade from Central Brazil, with notes on a new opisthosomal character (Arachnida: Palpigradi), Zootaxa 4869 (4), pp. 493-514 : 508

Taxonomy of E. audax

Eukoenenia audax shows affinity with other Brazilian troglobitic palpigrades and with the edaphic species E. improvisa Condé, 1979 from French Guiana. The absence of one esp seta on IVbta and the chaetotaxy of tergites II–VI (t 1, t 2, s) are shared with E. maquinensis , E. spelunca , E. sagarana , E. cavatica , E. neytiri , E. jequitinhonha , E. navi , E. eywa , E. ibitipoca , E. igrejinha , E. improvisa , E. magna , E. lundi , E. jequitai and E. virgemdalapa (in these three last species, seta gla is also absent on bta IV). The number of setae on sternites IV–VI (a 1, a 2, s) in the new species is also similar to those in most of the species previously mentioned, except E. maquinensis , E. sagarana and E. igrejinha ( Condé 1979a; Souza & Ferreira 2010, 2011b, 2012a, 2012b, 2016, 2018, 2019a, 2019b, 2020). The chaetotaxy of the female genitalia is similar to that of E. navi , E. eywa , E. neytiri , E. magna , E. lundi and E. jequitinhonha (some species have an asymmetrical or unknown condition). However, the chaetotaxy of the male genitalia is only shared with E. sagarana and E. lundi ( Souza & Ferreira 2012a, 2016, 2018, 2020).

The new species shares a similar coxal formula with E. navi , E. eywa , E. neytiri and E. magna . The general chaetotaxy of palp and leg I also resembles that of those species, as well as that of E. ibitipoca and E. igrejinha , but there are some differences. For instance, the number of setae on trochanter of leg I is 11 in Eukoenenia audax and 13 for all other species. In addition, E. audax carries 9n on ta3 of the pedipalp while E. navi , E. eywa and E. neytiri carry 11n setae, E. ibitipoca carries 13n and E. magna and E. igrejinha have 8n. On the other hand, E. audax , E. ibitipoca , E. magna and E. igrejinha have a forked seta (fs) on bta2 of leg I, but it is absent in E. navi , E. eywa and E. neytiri ( Souza & Ferreira 2018, 2019a, 2019b, 2020).

Eukoenenia audax can be differentiated from all South American species and from most palpigrades described to date by the presence of a single deutotritosternal seta. This character state is only shared with E. deleta Condé, 1992 from Thailand and E. vargovitshi Christian, 2014 from the Western Caucasus. A more detailed comparison with E. deleta is not possible since only two specimens were captured: an adult female that was lost before its description and an immature A on which the description of the species was based ( Condé 1992). E. vargovitshi differs from the new species in almost all other characters, i.e. number of setae on propeltidium (7 + 7 vs. 10 + 10), number of blades in lateral organs (9–11 vs. 3), number of setae on IVbta (6 vs. 4) and different ventral chaetotaxy on sternites IV–VI (Christian 2014). In addition to the deutotritosternal chaetotaxy, the position of the seta r on IVbta (distal to the insertion of the pair esd) and the number of blades in the lateral organs (9–11 in adults) are unique characters among Brazilian palpigrades.

The number of propeltidial setae is also distinctive in the new species. While most species of palpigrades carry 10 + 10 setae on the propeltidium, Eukoenenia audax carries 7 + 7. This character is shared with only 7 other species of Eukoenenia : E. maquinensis , E. sagarana , E. navi , E. eywa , E. neytiri and E. magna from Brazil, and with E. naxos Condé, 1989 from Greece ( Condé 1989; Souza & Ferreira 2010, 2012a, 2018, 2020).

The presence of 2 thickened setae (a 1, a 2) and one seta (s) on sternites IV–VI relates the new species with some other Brazilian species, as discussed above, but also with E. improvisa Condé, 1979 , E. lyrifer Condé, 1992 , E. pauli Condé, 1979 and E. thais Condé, 1988 . All these other species have a different deutotritosternal setae formula (1 vs. 5–7), number of setae on propeltidium (7 + 7 vs. 10 + 10) and smaller legs, i.e. IVbta 215–238 vs. 62–117 (Note: for E. thais Condé reported two values for IVbta, 117 and 223) ( Condé 1979a, 1979b; 1988; 1992).