Denisiella Folsom & Mills, 1938

Medeiros, Gleyce da Silva, Silva, Clecio Danilo Dias da, Franca, Josemaria Silva de, Godeiro, Nerivania Nunes & Bellini, Bruno Cavalcante, 2023, Two new species of Sminthurididae (Hexapoda, Collembola, Symphypleona) from Brazil with notes on Denisiella Folsom & Mills and Sphaeridia Linnaniemi, ZooKeys 1173, pp. 1-41 : 1

Genus Denisiella Folsom & Mills, 1938

Diagnosis of the genus.

Males with highly dimorphic antennae, Ant II with Tra1-2, b1-b7 elements, b1-b6 together, b7 isolated, Ant III with Tra3 as a bothriotrichum or a regular chaeta, elements c1 and c3 always present. Ant IV undivided in both sexes, usually with blunt sensilla. Eyes 6+6 to 8+8. Th III and large abdomen in males without vesicles. Bothriotricha ABC misaligned. Posterior large abdomen with or without long chaetae. Ventral tube without modifications. Each anal valve with 0-2 barbulated spines in both sexes. Tibiotarsus I proximal organ usually present in males, formed by four modified sensilla. Tibiotarsus II with or without a polycarinate chaeta. Tibiotarsus III with 0-5 serrated spines in both sexes. Distal tibiotarsal organ on leg III absent. Dens lacking spine-like chaetae. Mucro narrow, inner edge serrated, outer smooth, mucronal chaeta present (adapted and revised from Börner 1908; Denis 1925; Denis 1931; Folsom 1932; Snider 1988; Palacios-Vargas 1995; Palacios-Vargas and Bernava 1999; Palacios-Vargas 2007; Ospina and Palacios-Vargas 2009; Schulz and van Harten 2013; Palacios-Vargas et al. 2018).

Type species.

Sminthurides seurati Denis, 1925.

Distribution.

Americas, Africa, and Indo-Asia ( Bellinger et al. 1996-2023).

Remarks.

Denisiella species arguably have the most sexually dimorphic antennae among all the Sminthurididae , with several modified elements on the male claspers ( Massoud and Betsch 1972; Betsch 1980; Medeiros et al. 2022). The morphology of such elements varies between the species (Fig. 13 ), but even so, most of them are present, with the exception of the c2 element on Ant III, which may be absent in some species ( Börner 1908; Denis 1931; Palacios-Vargas and Bernava 1999; Schulz and van Harten 2013), and Tra3 on Ant III, which interchanges between a regular chaeta or a bothriotrichum ( Denis 1925; Palacios-Vargas 1995; Palacios-Vargas et al. 2018) (Table 2 ).

In the same way as to many other Sminthurididae , including Sphaeridia , the diagnosis and comparisons between Denisiella taxa is mostly based on males’ morphology. Because of this, some Denisiella descriptions lack data on the females’ morphology, especially regarding the antennal and abdominal chaetotaxy ( Börner 1908; Denis 1931; Palacios-Vargas 2007; Schulz and van Harten 2013; Palacios-Vargas et al. 2018). In our survey we observed D. nayarita Palacios-Vargas and Bernava, 1999 and D. sexpinnata (Denis, 1931) were described based only on females, while their males’ morphology is completely unknown. So, we suggest both taxa as species inquirendae, as their identities are not fully clear and it is not possible to clearly distinguish them from other taxa, especially from those described based only on male morphology. In a similar way, D. serroseta ( Börner, 1908) description lacks information about the male antennae, small and large abdomen of both sexes, and shows unclear data on the chaetotaxy of legs and furca. In this scenario this description does not fit the current taxonomy of Sminthurididae and does not allow us to clearly separate the species from its congeners; therefore, we also suggest D. serroseta as a species inquirenda.

Some species of Denisiella can be readily distinguished from several others by the presence/absence of a unique feature located between de clypeal and interantennal areas of male head, the nasal organ ( Palacios-Vargas et al. 2018). Since this structure is formed by strongly modified projections, we believe it may have a phylogenetical significance and probably points to different lineages within the genus. So here we tentatively separate the genus in two distinct groups: the Denisiella seurati group, for the species without the nasal organ, holding: D. betschi Palacios-Vargas, Ferreira & Zeppelini, 2018, D. colombiana Ospina & Palacios-Vargas, 2009, D. lithophila Snider, 1988, D. maesorum Palacios-Vargas, 1995, D. ramosa Folsom, 1932, D. rhizophorae Palacios-Vargas, Ferreira & Zeppelini, 2018, D. seurati Denis, 1925, D. serroseta Börner, 1908 and D. piracurucaensis sp. nov.; and the Denisiella diomedesi group, for the species with the nasal organ, with the species: D. bretfeldi , Schulz & van Harten, 2013, D. caatingae Palacios-Vargas, Ferreira & Zeppelini, 2018 and D. diomedesi Palacios-Vargas, 2007.

Figures

Figure 13. Chaetotaxy of Ant II and III of males of Denisiella A D. betschi Palacios-Vargas, Ferreira & Zeppelini, 2018 B D. caatingae Palacios-Vargas, Ferreira & Zeppelini, 2018 C D. colombiana Ospina & Palacios-Vargas, 2009 D D. diomedesi Palacios-Vargas, 2007 E D. lithophila Snider, 1988 F D. maesorum Palacios-Vargas, 1995 G D. ramosa (Folsom, 1932) H D. rhizophorae Palacios-Vargas, Ferreira & Zeppelini, 2018 I D. seurati (Denis, 1925) (ventral view). Figures adapted from species' original descriptions.

Figure 15. Denisiella piracurucaensis sp. nov. antenna (dorsal view) A - D male antenna A Ant I B Ant II C Ant III D Ant IV E - H female antenna E Ant I F Ant II G Ant III H Ant IV.