Corethrella (Corethrella) miocaenica Szadziewski, Krzeminski and Kutscher, 1994

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 201-202

Corethrella (Corethrella) miocaenica Szadziewski, Krzeminski and Kutscher

Corethrella miocaenica Szadziewski, Krzeminski and Kutscher 1994:87 . Type-locality: Germany. Holotype ♂ (ISZP).

DIAGNOSIS: Male adult: only fossil species of Corethrella with elongate, equal fore- and midleg claws with the anterior claw with a basal prong, without empodia (as in Fig. 75C), and a short aedeagus (not extending much beyond base of gonocoxites). Female adult: unknown.

DESCRIPTION: Male adult. Habitus as in Fig. 112C. Descriptive statistics: see Tables 2–5. Head: Outline in anterior view uncertain, likely nearly circular (as in Fig. 6A). Number of large setae on frons between ventromedial area of ommatida uncertain. Antenna: pedicel without more elongate, stout, dorsal or dorsolateral setae; flagellomeres as in Fig. 25D; sensilla coeloconica not visible; flagellomere 13 apex extended with 2 apical sensilla, not bifurcate. Clypeus with single elongate setae, numerous (at least 10) shorter setae. Palpus ( Fig. 35 AE) with segment 3 slightly swollen apically. Thorax: Posterior portion of dorsocentral row with 2 elongate setae situated somewhat lateral to one another. Prescutal suture uncertain. Details of shapes of pleura uncertain. Wing: Apex of R 2 basal to apex of M 1. Veins (other than costa and wing margin) with very slender scales. Legs: With only slender setae, lacking scales (except for some in patch of whip-like setae on posterior portion of hind tibia). Midleg without thick, subapical setae on each of at least tarsomeres 1–3. Apices of fore-, midleg fifth tarsomeres undivided, with claws slightly subapical to apical (as in Fig. 75C; Figs. 4, 5 in Szadziewski et al. 1994). Claw of fore-, midleg long; those of hind leg claws missing. Each claw without inner tooth. Anterior claws of fore-, midleg with basal prong. All claws on given leg equal length. Foreleg third tarsomere longer than fourth tarsomere. Empodia absent. Genitalia ( Figs. 6–9 in Szadziewski et al. 1994): Gonocoxite gently tapering; anteromedial area with spicules similar in length to those elsewhere on gonocoxite; with well-defined dorsal row of setae of 4 setae, with seta 1 thinner than 3 posteriormost setae, with row curving posteromedially with posteriormost seta of row positioned dorsomedially. Without dorsomedial seta. Gonostylus (Fig. 99C) (in retracted position) straight, thick; expanding distally to truncate apex; one elongate, moderately thick subbasal seta, situated ventrally; with well-developed apical seta, possibly a peg (more clearly seen in other gonostylus drawn by Szadziewski et al. (1994). Aedeagus short, possibly bilobed, details uncertain.

Female adult and immatures. Unknown.

DISTRIBUTION AND BIONOMICS: Corethrella miocaenica is known from Saxonian amber (Fig. 139), dated at 44.1 Mya. This amber was previously stated to be 22 million years old but has since been discovered to be contemporaneous with Baltic amber ( Weitschat 1997). The amber piece bearing the holotype includes some trichomes and the tarsomeres of an unidentified insect.

TAXONOMIC DISCUSSION: The Baltic amber specimen identified by Sontag (2001) as C. miocaenica is here described below as C. baltica . The holotype of C. miocaenica is in excellent condition with only the apices of the right wing, and the tarsomeres of the right foreleg, right midleg and both hind legs missing. The amber with the specimen was further ground and polished for this study, giving a somewhat enhanced view of some structures.

Szadziewski et al. (1994) recorded the wing length of the holotype as 1.54 mm, while my measurement is 1.32 mm. The difference is due to the measurement here being taken from the arculus, rather than the very base. Szadziewski et al. (1994) also showed the bases of Sc and R to be fused but this was a misinterpretation based on the position of the wing. In fact, they are separate throughout their length. The subbasal seta on the gonostylus was visible and is therefore redrawn here.

Although C. miocaenica lacks many features of the subgenus Corethrella , it is placed here because it has derived character states 14, 16' and 17 (male claws lacking teeth, Ta 3 /Ta 4 of less than 1.60, gonocoxite with dorsal row of setae) (Fig. 143B). Szadziewski et al. (1994) put this species in the subgenus Notocorethrella because of its similarity to C. novaezealandiae (the only extant member of the subgenus). However, phylogenetic interpretation indicates that C. miocaenica is more closely related to members of the subgenus Corethrella than to C. novaezealandiae (Fig. 143B).

MATERIAL EXAMINED: Holotype, adult male in amber on microscope slide, labeled “ HOLOTYPE Corethrella miocaenica Szadziewski, Krzeminski and Kutscher ”, “Saxonian amber coll. Kutscher, Diptera : Corethrellidae , Corethrella miocaenica sp. n., holotype ♂ ”, “Collection: Kutscher coll., Housed in: Inst. Systematic and Evol. of Animals , Ordo: Diptera , Family (subfamily): Corethrellidae , Species: Corethrella miocaenica Szadziewski, Krzeminski and Kutscher (1994) , Det.:, Specimen No. MPK 3/1/03 - ♂, HOLOTYPE, Szadziewski, R., Krzeminski, W. and Kutscher, M. 1994, A new species of Corethrella ( Diptera , Corethrellidae ) from Miocene Saxonian amber. Acta zool. cracov. 37(2):87–90” ( ISZP).

DERIVATION OF SPECIFIC EPITHET: The name miocaenica refers to perceived age of the specimen.