Gerontodacus, Borkent, 2019

Borkent, Art, 2019, The phylogenetic relationships of Cretaceous biting midges, with a key to all known genera (Diptera: Ceratopogonidae), American Museum Novitates 2019 (3921) : -

Gerontodacus , new genus

TYPE SPECIES: Gerontodacus succineus (Szadziewski) by present designation.

DIAGNOSIS: The only Cretaceous genus of Ceratopogonidae without R 4+5, with 2 radial cells, r-m oblique to R 1 (fig. 6B), an elongate anapleural suture (as in fig. 1A), a foreleg tarsal ratio/hind-leg tarsal ratio ≤ 1.3, and fore- and midtrochanter each lacking a pair of thick setae. To further distinguish Gerontodacus females from those of Protoculicoides , Gerontodacus have a squat, semispherical antennal pedicel (fig. 4F, G) while those of Protoculicoides have an elongate pedicel (figs. 1B, C, 2B, 4D).

REMARKS: Aside from the type species, there are three further species included in the genus, as follows: G. krzeminskii (Choufani, Azar, and Nel) , new combination, G. punctus (Borkent) , new combination, and G. skalskii (Szadziewski and Arillo) , new combination.

The type species, G. succineus , has plesiomorphic conditions that exclude it from the lineage defined by synapomorphies 11’, 12–13, has synapomorphies 6–7 and lacks synapomorphy 8 (fig. 10) and is here stated to be the type species of Gerontodacus . Although the character states 9, 11’, 12–13 could not be examined for G. krzeminskii (Choufani, Azar, and Nel) , G. punctus , and G. skalskii (Szadziewski and Arillo) , these species are placed in Gerontodacus because of overall similarity to G. succineus . They lack synapomorphy 8 and G. punctus has synapomorphy 7 (males are unknown for the other two species). There is no synapomorphy indicating the monophyly of Gerontodacus . As such the placement of G. krzeminskii , G. punctus , and G. skalskii is tenuous. Likewise, it is possible that with further analysis the nontype species will be recognized as further distinct lineages within this region of the phylogeny.

Recent examination of Burmese amber reveals that at least one unnamed species of Gerontodacus is present.

BIONOMIC INFORMATION: The details of the mouthparts of only one species were evident ( Borkent, 2000a). The presence of fine mandibular teeth and retrorse lacinial teeth indicates that at least female G. punctus fed on vertebrate blood ( Borkent, 1995). The well-developed male antennal plume of G. succineus and G. punctus indicates that, similar to most Ceratopogonidae , the males formed mating swarms.

ETYMOLOGY: from the Greek geron (“old one”) and dacus (“biter”).