Stenoxenus, Borkent, 2024

Borkent, Art, 2024, The Phylogeny of the Genera of Biting Midges (Diptera: Ceratopogonidae) of the World, Zootaxa 5438 (1), pp. 1-274 : 238-242

publication ID

https://doi.org/ 10.11646/zootaxa.5438.1.1

publication LSID

lsid:zoobank.org:pub:2CD64E2C-D575-463F-A8F4-390662DDC9E2

persistent identifier

https://treatment.plazi.org/id/5875621C-FF46-29B9-FF3F-B740FB32727F

treatment provided by

Plazi

scientific name

Stenoxenus
status

 

Stenoxenus View in CoL :

- Male anterior tentorial pit expanded ventrally, in anterior view appearing as a ventrally directed prong or in lateral view as fan-shaped, attached to the lateral margin of the clypeus ( Fig. 15D View FIGURE 15 ) (absent or slightly developed in all others).

- Female with only one stout and elongate medial scutal apodeme (lateral apodemes are absent). This feature is unique (but see Leptohelea ).

- Female with base of M 2 strongly bent. This feature is unique within Culicomorpha.

Discussion

Realigned, Synonymized or Poorly Understood Genera

The following section discusses a number of genera needing specific comment, all arranged in alphabetical order. Some were not incorporated into the phylogenetic analysis either because they are too poorly understood or otherwise have too limited information and some have been synonymized with another generic name or are reassigned to a different tribe. Several genera described from China, especially by Yu et al. (2005) are either here considered synonyms of other genera or are too poorly understood to place phylogenetically. None could be examined firsthand, a serious problem that has continued for decades. As such, some of these previously named Chinese genera will certainly be interpreted more fully once re-examined.

The character states noted for the genera below are described more fully in the phylogenetic portion of this paper or in the section “Uncertain Character States”.

Agilihelea —A monotypic Chinese genus based on a single male, was interpreted by Yu et al. (2005) as similar to Stilobezzia and Downeshelea . There were too few features described to interpret the phylogenetic position of this genus and it has been excluded from the phylogenetic analysis. It is clearly a member of the Ceratopogonini .

Alloimyia —This monotypic Chinese genus is known from two females and was considered by Yu et al. (2005) to be similar to Mackerrasomyia and Lanehelea (members of Johannsenomyiini ). The tarsomere 5 of each leg appear to have a double row of batonnets and equal claws, placing them in Johannsenomyiini or Sphaeromiini . The abdominal sternite 8 lacks setal tufts (character 136) ( Borkent 2015), again indicating that it belongs in either Sphaeromiini or within Johannsenomyiini . The presence of thick spines on each femur is also present in some Johannsenomyiini , some Sphaeromiini and some Palpomyiini (see character 89). Finally, the lack of stout, outer teeth on the claws excludes it from Johannsenomyiini . The ratio of fore- to hind tibia of 0.58 (character 85) excludes it from Indobezzia + Homohelea + Xenohelea + Sphaeromias + Leehelea . As such this limited evidence indicates the genus remains in Sphaeromiini , possibly as sister to Indobezzia + Homohelea + Xenohelea + Leehelea + Sphaeromias .

Boreohelea —The genus Boreohelea was considered a synonym of Allohelea by Alwin-Kownacka et al. (2016) and treated as such by Borkent (2017) and in the world catalog by Borkent & Dominiak (2020). This monotypic genus, known only from the holotype female, is here considered a distinct genus, new status. It does not share the autapomorphies otherwise attributed to Allohelea : it has a hind femur width/ hind tibia width ratio of 1.16, somewhat similar to that of Allohelea but different and a hind tibia width/ foretibia width ratio of 1.67, similar to many other Ceratopogonidae . The hind leg has a moderately thick apical spine on each of tarsomeres 1–4 (a second subapical spine on tarsomere 4), similar to numbers of other genera. It also lacks the synapomorphies otherwise grouping Monohelea + ( Allohelea + Downeshelea ) other than character 27 (frontoclypeal with a transverse suture). Although not cladistic evidence, Boreohelea lacks wing pigmentation otherwise present in all Monohelea , Allohelea and Downeshelea . The description by Clastrier & Delécolle (1990) noted the abdomen was deformed and poorly oriented; I soaked the abdomen off the slide and observed it in clove oil from a ventral angle, allowing for its further interpretation. The abdomen was further dissected and its apex, still somewhat distorted, is now in a dorsoventral orientation on the slide. The female genitalia are distinctive in at least two features (see under “Autapomorphies”). Once the male is discovered there will be further important character states to interpret the position of Boreohelea .

Chairopogon — Yu et al. (2005) noted that this monotypic Chinese genus, known from a single female, was very similar to Culicoides and Ceratopogon . Of the available character states described, the presence of sensilla coeloconica on flagellomeres 1–8 (character 25, flagellum with sensilla coeloconica on at least three flagellomeres a synapomorphy of Culicoides + Paradasyhelea ) and 22 fine mandibular teeth (character 35, excluding it from Washingtonheleini and remaining Ceratopogoninae ( Fig. 5 View FIGURE 5 )) indicates that belongs to the Culicoides + Paradasyhelea clade. The lack of palisade setae on the hind tarsomere 1 (see character 95) indicates it cannot belong to Ceratopogoninae other than Culicoidini and Washingtonheleini and some Ceratopogon . The presence of three spermathecae is not informative as it is present in most Ceratopogon and some Culicoides (e.g. C. (Trithecoides), C. ( Pontoculicoides )). The wing of Chairopogon has only one radial cell and with the radial area compacted, similar to that of some Brachypogon (Brachypogon) and differing from all Culicoides . However, the radial cells of species of Culicoides vary strongly, with 1–2 well-developed cells or these being absent (e.g. C. taylori ( Boorman & Lane 1979) . Compacted radial cells are discussed further under “Uncertain Character States” as “R 1 and R 3 joining costa as a strong, thickened fusion and with either no or one radial cell evident or with veins forming the second (or last) radial cell are swollen”. Yu et al. (2005) describe the abdomen as having sternite 7 and 8 fused. It is uncertain whether this condition occurs in at least some other Ceratopogonidae . In many, including some Culicoides , sternite 7 and 8 appear closely appressed and at least partially fused. Here I remove Chairopogon from the Ceratopogonini ( Borkent & Dominiak 2020) and consider it to be a subgenus of Culicoides , new status, with partially fused radial cells and with the caveat that phylogenetic studies may question its validity (perhaps just an autapomorphic species within another subgenus or grouping). As such the type species is now named Culicoides (Chairopogon) chengdeiensis (Yu & Hao, in Yu et al. 2005): 1430. New combination.

Chelohelea —This monotypic genus from Malaysia, known as a single female, is represented by an uncleared specimen on a slide. Because the specimen is dark, some characters could not be scored. Regardless, the genus is considered a member of the Sphaeromiini because of a combination of well-developed batonnets on the fifth tarsomeres (character 101), the lack a synapomorphy grouping Johannsenomyiini (character 107: an outer tooth on each claw) and those grouping the Palpomyiini + Stenoxenini (characters 106: claws not fused, 133: presence abdominal tergal apodemes and eversible sacs, 134: abdominal tergite 8 short) (character 26 could not be seen). As such, it’s placement is based largely on plesiomorphies. The female of Chelohelea has closely abutting eyes, a feature present in a few genera of Ceratopogoninae (see character 2) and present in Sphaeromiini in Xenohelea , Leehelea and some Sphaeromias . The eyes are very narrowly separated in Homohelea (by 1 ommatidium width) and some other Sphaeromias (up to 3 ommatidia). This may indicate that Chelohelea is related to this group of Sphaeromiini , where it is presently retained. Giles & Wirth (1985) considered the genus close to Lanehelea (here placed in Johannsenomyiini ), another poorly understood genus, apparently because of where it keys out in Wirth et al. (1974) and they discuss how to distinguish the two.

Congohelea —Another monotypic genus is based on a single female from the Republic of the Congo and which is poorly preserved ( Wirth & Grogan 1988; pers. obs.). The head, thorax and abdomen are not cleared and are badly shrivelled. Examination several years ago indicated that the sensilla coeloconica on the first flagellomere could not be confirmed. The mid- and hind leg claws are each a single claw with and elongate tooth. Although clearly a member of the Ceratopogonini , its phylogenetic resolution likely awaits fresh material.

Groganhelea —A monotypic Brazilian genus known from five females ( Spinelli et al. 1995). The presence of character 136 (sternite 8 with setal tufts) indicates that this genus forms at least a basal lineage within the assemblage defined by this synapomorphy. The presence of character 107 (claws with stout, outer teeth) confirms that it is a member of the Johannsenomyiini .

Guihelea —This monotypic Chinese genus is known only as a single male ( Yu et al. 2005). Here I consider it a New synonym of Johannsenomyia . The presence of thick spines, including batonnets on the hind tarsomere 5 (character 102) and external teeth on the claws (character 103) is shared with Johannsenomyia and Lanatomyia . The row of setae on the posterior margin of the epandrium is shared with only some Johannsenomyia (e.g. J. argentata ) and is likely a synapomorphy grouping these. The presence of a single radial cell is also present in some Johannsenomyia (although this feature is strongly homoplastic; see discussion under “Uncertain Character States”). Similarly, some male Johannsenomyia have unequal hind claws (reduced to one in Guihelea ) and the apical “head-like” shape of the paramere is also uniquely shared. As such, the type species is now named Johannsenomyia jingxiensis (Yu & Qian, in Yu et al. 2005): 1497. New combination.

Heteroceratopogon —This monotypic genus was described by Wirth & Grogan (1988: 55) based on a species from New Caledonia. The genus is similar to an Eocene fossil and monotypic genus * Ceratopalpomyia described by Szadziewski (1988: 171). Notably, both have a swollen forefemur with ventral spines and similar antennae, wing venation and claws. The medial veins M 1 and M 2 have a more petiolate base in fossil Ceratopalpomyia than the extant species but this should be confirmed. Furthermore, the male genitalia differ in that Heteroceratopogon has tiny gonostylus, while that of Ceratopalpomyia is well-developed. I consider this a relatively small difference (see “Male gonostylus relative size” under “Uncertain Character States”). Notably, the elongate, slender, “rod-like” parameres are shared between the two genera. Because Ceratopalpomyia was published earlier in the year than Heteroceratopogon , it is Heteroceratopogon which is considered a New synonym of Ceratopalpomyia . As such, the single included species in Heteroceratopogon is now named Ceratopalpomyia poguei (Wirth & Grogan. New combination.

Hypsimyia —This monotypic Chinese genus, known only as single male, is here considered a synonym of Ceratopogon , New synonym. The male genitalia, as drawn by Yu et al. (2005: Figs. 6–78 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURE 11 View FIGURE 12 View FIGURE 13 View FIGURE 14 View FIGURE 15 View FIGURE 16 View FIGURE 17 View FIGURE 18 View FIGURE 19 View FIGURE 20 View FIGURE 21 View FIGURE 22 View FIGURE 23 View FIGURE 24 View FIGURE 25 View FIGURE 26 View FIGURE 27 View FIGURE 28 View FIGURE 29 View FIGURE 30 View FIGURE 31 View FIGURE 32 View FIGURE 33 View FIGURE 34 View FIGURE 35 View FIGURE 36 View FIGURE 37 View FIGURE 38 View FIGURE 39 View FIGURE 40 View FIGURE 41 View FIGURE 42 View FIGURE 43 View FIGURE 44 View FIGURE 45 View FIGURE 46 View FIGURE 47 View FIGURE 48 View FIGURE 49 View FIGURE 50 View FIGURE 51 View FIGURE 52 View FIGURE 53 View FIGURE 54 View FIGURE 55 View FIGURE 56 View FIGURE 57 View FIGURE 58 View FIGURE 59 View FIGURE 60 View FIGURE 61 View FIGURE 62 View FIGURE 63 View FIGURE 64 View FIGURE 65 View FIGURE 66 View FIGURE 67 View FIGURE 68 View FIGURE 69 View FIGURE 70 View FIGURE 71 View FIGURE 72 View FIGURE 73 View FIGURE 74 View FIGURE 75 View FIGURE 76 View FIGURE 77 View FIGURE 78 ) clearly shows the tuberculate mediobasal lobe of the gonocoxite, a synapomorphy grouping 18 other species in this genus ( Borkent & Grogan 1995, their synapomorphy 16). The apically truncate epandrium is similar to that in this same group ( Borkent & Grogan 1995, their synapomorphy 17) although it is likely that Yu et al. (2005) missed the apicolateral process seta(e). Other features as described and drawn by Yu et al. (2005) also fit the genus, other than the apically broadly bifid apex of the aedeagus; the aedeagus of other Ceratopogon are divided into two elongate prongs ( Borkent & Grogan 1995, their synapomorphy 1). As such, their type species is named Ceratopogon emeiensis (Yu and Li, in Yu et al. 2005): 1433. New combination.

Indobezzia —Known from two Indian species ( Das Gupta & Saha 1995), this genus is placed in Sphaeromiini and shares at least two synapomorphies with Homohelea , Xenohelea , Sphaeromias and Leehelea , namely characters 89 and 93 (ratio of fore- to hind tibiae measured for this study = 0.93–1.03; all femora with ventral spines, respectively). It also shares abutting eyes (character 2) with Xenohelea , Leehelea and some Sphaeromias (see also Chelohelea above). Das Gupta & Saha (1995) described the claws of this genus as “each claw flanked externally at base by a small, stout tooth-like process” perhaps indicating that this genus shares character 107 with many Johannsenomyiini ; however, photomicrographs of the two species show these to be simple and certainly unlike those of those Johannsenomyiini with the synapomorphy. Similarly, their description of the thorax as “bears microspines” and having “small setulae in microtubercles”, perhaps describing character 60 (without defined rows and with short setae otherwise scattered on scutum) differs from a photomicrograph of at least I. recens with well-developed scutal setae (further study warranted). Das Gupta & Saha (1995) considered the genus to key out to couplet 45 in Wirth et al. (1974) and therefore distinguished it from Dibezzia , Xenohelea , and Hebetula (as Mixohelea Kieffer ). However, in their ground-breaking work, Wirth et al. (1974) mistakenly characterized (in their couplet 42) these genera as having abdominal sternite 8 with hair tufts (here character 136) but which actually characterizes those genera leading from their couplet 54. Das Gupta & Saha (1995) additionally misinterpreted Indobezzia as having claws each with a “blunt, external, basal tooth” (in the key).

Lanehelea —This genus includes two species from Colombia, known only as females ( Wirth & Blanton 1972). Previously placed in the Sphaeromiini ( Borkent & Dominiak2020) , Lanehelea is here placed in the Johannsenomyiini , based on somewhat weak evidence. The presence of batonnets on tarsomeres 5 (character 101) indicates that it belongs to a broader higher lineage. Character 134 (abdominal tergite 8 short) is shared with Austrosphaeromias , Mackerrasomyia and Neosphaeromias within Johannsenomyiini . In addition, the posterior margin of the anterior anepisternum bears setae (see character 69) and this is shared with Mackerrasomyia and some Neosphaeromias , possibly indicating relationship with these two genera specifically. However, both these features exhibit some homoplasy. The genus lacks the outer tooth on its claws, otherwise present in nearly all other Johannsenomyia (not Austrosphaeromias ). It lacks the synapomorphies present in Palpomyiini and Stenoxenini indicating that it does not belong there (with the possible exception of the short tergite 8).

Luciamyia This monotypic genus, known as a male and a female, were collected together at St. Lucia, Zululand (= KwaZulu-Natal), South Africa. There are too few characters of phylogenetic importance described to be able to say anything more than that the species belongs in Ceratopogonini . The types were studied by Wirth & Grogan (1988) and Downes (pers. comm.) but now appear to be lost .

Leptohelea —This monotypic genus was described by Wirth & Blanton (1970a) in which they wrote that the genus is “so anomalous that its systematic position is difficult to access” but that most features indicate it belongs in the “ Ceratopogon group” of Macfie (1940) (here = Ceratopogonini , in part). Here the genus is considered as part of a monophyletic group: ( Camptopterohelea + Leptohelea ) + ( Cacaohelea + Parastilobezzia ).

Borkent et al. (2008b) placed the genus with the other genera here classified in Parabezziini but this was based mostly on proposed synapomorphies here considered to be flawed (see “Uncertain Character States”), namely, costa extending beyond apex of R 3 (their character 3, also grouping Atyphohelea and Ceratopalpomyia (as Heteroceratopogon )) and wing with one radial cell (their character 4). Another synapomorphy exhibits homoplasy: adult palpus with four segments, with segments four and five fused (their character 10; here discussed as character 44).

Spinelli et al. (2018) produced a matrix analyzing most of the genera here placed in Parabezziini but using Bahiahelea as the sole outgroup (a problem discussed above under “Phylogenetic methods and approach”; Borkent 2018). They included Leptohelea , following Borkent et al. (2008b) and used mostly a combination of features here considered to be uncertain (their characters 1–5, 9, 10). Examination of their matrix shows that only one feature, the fusion of palpal segment 4+5 is shared as a potential synapomorphy with members of this tribe and this is interpreted differently here (character 44), as one of several synapomorphies grouping it with Camptopterohelea + Cacaohelea + Parastilobezzia .

Borkent et al. (2008b) indicated that female Leptohelea had the frontoclypeus fused to the eye (their character 1; here as character 29, state 2) but re-examination of the holotype (paratype not available) makes this questionable. The head is crushed and relatively lightly pigmented and details are uncertain. Similarly, as discussed by Borkent et al. (2008b), the shape of the anapleural suture is uncertain (their character 2; here as character 70). In short, Leptohelea does not appear to have any synapomorphies grouping it with Parabezziini . However, there are a number of characters which could not be determined and these, grouping Parabezziini with remaining higher tribes, should be studied with future material, namely characters 29, 38, 55 and 106. Character 19 cannot be appraised because the male has a female-like antenna. More basally on the phylogeny it will also be important to evaluate character 40.

Meunierohelea —This genus is known from one extant Australian species and eight fossil species ( Szadziewski 1988, 1993; Stebner et al. 2017; Peñalver et al. 2021). Debenham (1988) described the male and female of the extant species M. caligula (as a species of Chimaerohelea Debenham ) and suggested the genus belongs in Stilobezziini (combined with Ceratopogonini by Wirth & Grogan 1988) and that it was “near Serromyia and the complex of genera clustered around Monohelea ”. Here, it is placed in the Neurobezziini (formerly these genera were part of Ceratopogonini ), based on character 21 (male flagellomere 10 with setae in a transverse row). There are three reversals in the extant species of Meunierohelea (these features not described for the fossil species), of characters 78.1 (radial vein with basal portion near arculus bare), 92 (midtibia without subapical spine) and 106 (claws fused) but all these features are homoplastic in some other taxa and 92 is sometimes difficult to determine. Although the base of M 2 is absent in all Meunierohelea , the description of the female of M. caligula shows the basal portion of M 2 extending basal to r-m ( Debenham 1988: Fig. 3 View FIGURE 3 ), indicative of taxa with character 82. Examination of the male here also shows M 2 extending well basal of r-m. Illustrations of fossil species show the basal portion of M 2 ending distal to the level of r-m ( Szadziewski 1988, 1993; Stebner et al. 2017; Peñalver et al. 2021). However, the photomicrographs of * M. borkenti Stebner & Szadziewski and * M. orientalis Stebner & Szadziewski by Stebner et al. (2017, their Figs. 7D, E View FIGURE 7 ) suggest that the basal portion of M 2 does extend basal to the level of r-m in at least these two fossil species. It would be valuable to check these various features in all the fossil species. Synapomorphy 70.2 (narrow anepisternal cleft) is further good evidence that the genus is not in the Ceratopogonini . Although photomicrographs of the head of the female of M. caligula were kindly provided, the arrangement of the mouthparts, particularly the cardo, stipes and postgena remain unclear and the original specimen needs firsthand reexamination to test the placement of this genus. Further to this, fresh material will allow for examination of some further thoracic features presently scored as questionable.

Niphanohelea —A monotypic genus known from a single female from Thailand. The presence of character 136 (sternite 8 with setal tufts), character 78 (radial vein with basal portion near arculus bare), characters 139 (sternite 9 with thick medially directed setae) and 140 (tergite 9 split medially) indicate that it is the sister group of Nilobezzia + Crispomyia . Grogan & Wirth (1981a) proposed Niphanohelea as the sister group of Calyptopogon , as part of a broader analysis of those genera with claws with stout, outer teeth; this is discussed below under “Previous Phylogenetic Analyses” and character 107. The peculiar wing venation of this genus is discussed in the section on autapomorphies and under “Previous Phylogenetic Analyses”.

Oxyria —This monotypic Chinese genus, known only as a single male, was considered by Yu et al. (2005) to be related to Metacanthohelea and Meunierohelea as ( Chimaerohelea ) but it is likely a Forcipomyia . Although unusual in not having wing macrotrichia, the form of the genitalia is similar to many in the genus, the terminal nipple on flagellomere 13 is a synapomorphy of the Forcipomyiini , the elongate flagellomere 10 (longer than all other flagellomeres) is unique to some taxa within Forcipomyia and the long, curved shape of the claws typical of Forcipomyiini . The empodium is absent but this is also true of some other male Forcipomyia (i.e. F. ( Typhonomyia ), F. (Trichohelea )). The hindleg was drawn without palisade setae, typical of early lineages of Ceratopogonidae , including Forcipomyiinae . As such, Oxyria is removed from the Ceratopogonini ( Borkent & Dominiak 2020) and placed as a subgenus of Forcipomyia , new status, with the understanding that a cladistic study of the genus and particularly between the subgenera yet needs to be undertaken to determine valid subgenera. As such, the type species is now named Forcipomyia (Oxyria) xui (Yu, in Yu et al. 2005): 1437. New combination.

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Diptera

Family

Ceratopogonidae

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