Leptoconops, Skuse, 1889

Borkent, Art, 2024, The Phylogeny of the Genera of Biting Midges (Diptera: Ceratopogonidae) of the World, Zootaxa 5438 (1), pp. 1-274 : 221-222

Leptoconops :

- Males lateral coronal sutures are very strongly divergent ( Fig. 17B ), likely related to the widely spaced eyes in this genus (see Baeohelea below for a similar modification) (in others they are shorter and directed either dorsolaterally, dorsally, nearly forming a circle or, in a few, absent in all others).

- Female eyes broadly separated medially by span of unmodified cuticle ( Fig. 10A ). As discussed under character 2, the plesiomorphic condition in Ceratopogonidae is likely to have abutting ommatidia (or with abutting cuticle otherwise bearing ommatidia). Leptoconops is unique among extant members of the family in having the eyes broadly separated by unmodified cuticle, although this is superficial similar to some higher taxa with broadly separated ommatidia (e.g. some Macropeza , Calyptopogon ). The broadly separated eyes of Leptoconops is shared with two fossil genera, * Fossileptoconops and * Alautunmyia , which also have completely and broadly separated ommatidia with no distinction between the vertex and frons and this area being more or less homogeneous (other than the distribution of setae). This modification is considered a synapomorphy of these three genera, as originally proposed for Leptoconops and * Fossileptoconops by Szadziewski (1996: 81). * Alautunmyia was considered an unplaced genus by Borkent (2019a), largely because it is known only as females in only moderate condition and therefore could not be scored for a series of synapomorphies (i.e. Borkent 2019a: male characters 1, 2, 4, 7, 11; independent loss of character 3; characters 9, 12, 13 (spur absent or tiny), 16 not visible). Male Leptoconops have broadly separated eyes (similar to the female) but there is a transverse line of infolded cuticle, in some looking like a line of weakened cuticle in anterior view, which demarks the vertex and frons. In both males and females, the single median seta on the vertex (see character 6) is absent, likely related to the modification of the head described here.

- Female antenna with 11–12 flagellomeres. This is true for all extant species but members of the Cretaceous fossil subgenus L. ( Palaeoconops Borkent ) have 13. This autapomorphy was discussed by Borkent (2001: 8).

- The base of the anterior cervical sclerite is more slender ( Fig. 36A ), a unique condition in the Culicomorpha.

- The proepisternum is directed posteriorly where it articulates with the posterior cervical sclerite.

- Kaczorowska (2000) suggested that a narrow and curved subalar sclerite was a feature of Leptoconopinae (sensu Borkent et al. 1987, including just Leptoconops ) and this was confirmed as being unique, at least within the Ceratopogonidae . Austroconops has an elongate, slender and curved subalar sclerite which may also be unique but this was not studied further.

- Anepimeron and katepimeron at least partially fused. This feature is unique within the family, in which all others have two structures clearly defined by a suture (see Kaczorowska 2000: Figs. 18A, B ). Crampton (1925) shows the structures divided in Thaumaleidae , Simuliidae , but fused in Chironomidae and Dixidae . They are fused in Corethrellidae ( Borkent 2008) and separate in Culicidae ( Harbach & Knight 1980) .

- Female wing with R 1, R 2 and R 3 joining costa as a strong, thickened stigma. This feature was discussed by Borkent (1995: character 5; 2000a: character 6) and Borkent & Craig (2004: character 21). The feature is not unique in the family but has clearly evolved several times.

- Wing without r-m. This condition is nearly unique in Ceratopogonidae but r-m is also absent in the strongly modified wing of female Camptopterohelea , both clearly independent losses. This character was discussed by Borkent (2000a: character 5) and Borkent & Craig (2004: character 22) who reported it as unique within the Culicomorpha. Grogan & Wirth (1981a) considered r-m to be absent in Niphanohelea but I consider this a misinterpretation (see “Previous Phylogenetic Analyses”). Of two fossil genera in Leptoconopinae Baskintoconops Pielowska-Ceranowska also lacks r-m and Fossileptoconops may be missing it.

- Abdominal tergite 1 very short, especially medially and without dorsolateral ridge. This feature is unique in the Ceratopogonidae and discussed further under character 111.

- Female with posteromedial margin of sternite 8 with semicircular concavity bearing four or more (total from both sides) slender or stout setae on its margin. This feature, unique in Culicomorpha, was discussed by Borkent (2000a: character 7) and Borkent & Craig (2004: character 24) but with only “stout setae”. In at least some L. (Styloconops) the setae are slender.

- Female cercus markedly elongate. This feature is nearly unique in Culicomorpha, with only Telmatogetoninae ( Chironomidae ) also having an elongate cercus but this is clearly convergent, with many details differing. The elongate cercus of Leptoconops is not present in all taxa but its occurrence in L. ( Palaeoconops ) from 128 million year old Lebanese amber and the sister group to all remaining Leptoconops , shows that the shorter cerci of L. (Styloconops) and L. (Brachyconops Wirth & Atchley) are secondary reversals to the plesiomorphic condition (Borkent 2001). This feature has been further discussed by Borkent & Craig (2004: character 25).

- Larva have a strongly modified, weakly sclerotized head capsule with numerous unique (among Diptera ) and markedly derived features, as follows: head capsule with setae o represented by a single seta ( Borkent & Craig 2004: 47, character 2”), mandibles lying side by side medially ( Borkent & Craig 2004: character 16), an elongate apodeme extending from the genal arch posteriorly into the thorax (possibly the mandibular apodeme; see Borkent & Craig 2004: character 17), a dorsomedial rod extending anteriorly from the posterodorsal margin of the head capsule and a markedly reduced maxilla ( Clastrier 1971, 1972; Laurence & Mathias 1972; Hribar & Mullen 1991), with two anal papillae ( Borkent & Craig 2004: character 18). As homologies between Leptoconops and Austroconops are better understood, there will likely be more character states added here.

Figures

FIGURE 10. Head capsules of female Ceratopogonidae, in anterior view.A. Leptoconops catawbae (Boesel). B. Austroconops mcmillani. C. Forcipomyia (Synthyridomyia) murina (Winnertz). D. Forcipomyia (Lepidohelea) acinacis Wirth and Spinelli. E. Forcipomyia (Lasiohelea) fairfaxensis Wirth. F. Atrichopogon sp.

FIGURE 17. Head capsules of male Ceratopogonidae, in posterior view.A. Austroconops mcmillani. B. Leptoconops catawbae. C. Atrichopogon fusculus (Coquillett). D. Culicoides variipennis. E. Serromyia barberi Wirth. F. Atyphohelea macroneura (Malloch).

FIGURE 18. Head capsules of female Ceratopogonidae, in posterior view.A. Leptoconops catawbae. B. Atrichopogon fusculus. C. Culicoides variipennis. D. Clinohelea bimaculata.

FIGURE 36. Right cervical sclerites of female Ceratopogonidae, in anterior view (only half of posterior cervical sclerites shown, with most being continuous medially). A. Leptoconops (Holoconops) sp. B. Austroconops mcmillani. C. Atrichopogon sp. D. Culicoides saundersi Wirth & Blanton. E. Ceratopogon annettae Borkent & Grogan. F. Notiohelea pilosa Spinelli & Grogan. G. Macrurohelea n. sp. H. Sinhalohelea n. sp. I. Stilobezzia antennalis. J. Serromyia femorata (Meigen). K. Atyphohelea macroneura. L. Clinohelea curriei. M. Sphaeromias longipennis. N. Neobezzia costaricae Wirth & Ratanaworabhan. O. Paryphoconus angustipennis.