Trichoprosopon compressum Lutz

Harbach, Ralph E. & Wilkerson, Richard C., 2023, The insupportable validity of mosquito subspecies (Diptera: Culicidae) and their exclusion from culicid classification, Zootaxa 5303 (1), pp. 1-184 : 127-128

Trichoprosopon compressum Lutz

subspecies compressum Lutz, 1905 —original combination: Trichoprosopon compressum . Distribution: Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Panama, Paraguay, Venezuela ( Wilkerson et al. 2021).

subspecies mogilasium ( Dyar & Knab, 1907) —original combination: Joblotia mogilasia (varietal status by Stone 1944; subspecific status by Harbach & Howard 2007). Distribution: Brazil, Ecuador, French Guiana, Panama, Venezuela ( Wilkerson et al. 2021).

Trichoprosopon is a very poorly known genus.As currently defined, it only includes 14 formerly recognized species ( Wilkerson et al. 2021; Rivera-García et al. 2023), but there are an unknown number of undescribed species (T. J. Zavortink and the late E. L. Peyton, pers. comm., circa 1992). Based on this and what little is known about the morphology of the immature stages of compressum sensu stricto and mogilasium , it is difficult to know for certain whether they are the same or separate species. The pupa of compressum was fully illustrated by Knight & Chamberlain (1948) and the pupa and larva were briefly described and partially illustrated by Lane (1953). The immature stages of mogilasium have not been described.

The nominate subspecies was described from an “unspecified number of ♂ and ♀ from unspecified localities in the states of São Paulo and Rio de Janeiro, Brazil ” (Belkin 1968). Lane (1953) listed the type locality as “ Brasil, State of S. Paulo, Pindamonhanga”. The locality, however, has been misinterpreted to be equivalent to São Paulo ( Stone et al. 1959; Belkin 1968; Knight & Stone 1977; Wilkerson et al. 2021). The type locality is Pindamonhangaba, a municipality in the state of São Paulo located in the Paraíba Valley approximately 100 km northeast of the city of Sao Paulo. Subspecies mogilasium and Joblotia trichorryes Dyar & Knab, 1907 , a synonym of compressum (see below), were both described from specimens collected at Tabernilla in the Canal Zone of Panama.

The three nominal forms, compressum , mogilasium and trichorryes , have an interesting history. Joblotia mogilasia and J. trichorryes were described as separate species on the same page ( Dyar & Knab 1907), with the latter preceding the former. We believe the descriptions support their recognition as separate species, especially the presence of setae and scales on the clypeus of mogilasia and the presence of only setae on the clypeus of trichorryes . The two forms were listed as separate species in Panama by Dyar (1923), but five years later Dyar (1928) treated them as synonyms of J. compressa without explanation. This was in turn followed by Edwards (1932a), who listed them as synonyms of Tr. compressum . Lane (1936a), based on a single female collected on human bait at Nhandeara, a municipality in São Paulo State of Brazil, revalidated mogilasia as a species of Joblotia , based on “the fact that in our specimen the clypeus is laterally covered with dark scales and some setae that are barely perceptible” (translated from the Portuguese). Lane further noted that “If there really are no scales in the mogilasia type then our specimen is atypical or a new species.” Strangely, Lane & Cerqueira (1942) reasoned that because the presence of setae and scales on the clypeus “is the only character that separates the adults of T. mogilasium from those of T. digitatum and as the existing material is represented only by some females, we believe that it is preferable to consider T. mogilasium as a variety of T. digitatum until other phases of biology are known and the systematic position definitively established” (translated from the Portuguese). Stone (1944) noted that Lane & Cerqueira had discovered that scales may be present on the clypeus of both Tr. digitatum ( Rondani, 1848) and Tr. compressum , and they had incorrectly treated mogilasium as a variety of digitatum . Stone therefore established mogilasium as a variety of compressum , stating that it “agrees with typical compressum in all diagnostic characters save that there are some scales intermingled with the hairs [setae] on the sides of the clypeus.” The taxonomic status of mogilasium was confused until it was clarified by Harbach & Howard (2007) as follows: “ Knight & Stone (1977) indicated that Joblotia mogilasia was formally recognized as a subspecies of Tr. compressum by Stone (1944) and later afforded varietal status by Stone et al. (1959). This is incorrect as Stone (1944) unambiguously treated this nominal species as a variety of Tr. compressum . Because mogilasium was adopted (originally) as the valid name of a species prior to 1985, it is deemed to be subspecific with availability from its original publication ([ICZN] Article 45.6.4.1).”

In summary, setae and scales are present on the clypeus of mogilasium whereas only setae are found on the clypeus of compressum and trichorryes . In comparison with the detailed morphological descriptions of adult mosquitoes published post-Belkin (1962), the available descriptions of compressum , mogilasium and trichorryes reveal that specimens were not studied in detail and were only superficially examined. Lane (1953) provided the most recent treatment of species currently included in the genus, and for the most part his descriptions are very superficial and unsatisfactory. The three nominal forms considered here are based entirely on adult characters, principally general coloration of scaling and the length of various appendages. The adults may actually show many good characters, but these need to be studied in much greater detail than has been done by the authors cited above. The larvae and pupae of sabethine mosquitoes are known to exhibit striking anatomical differences ( Zavortink 1979), but these life stages, as indicated above, are either unknown or have not been studied in sufficient detail to evaluate their usefulness in recognizing and distinguishing similar species. In the case of the nominal forms of concern here, while it appears on superficial examination that only one variable species is involved, we suspect it is likely that several distinct sympatric forms may be present. This is supported by the recognition of a Compressum Complex by Zavortink (1981) that includes two “closely related [undescribed] allopatric taxa [which] occur in bamboo internodes and are apparently indistinguishable. However, in characteristics of the adults and male genitalia, these taxa differ to a much greater extent than do the sympatric species of the Tr. digitatum complex [see below], and so I consider these allopatric taxa to be distinct species.” Zavortink did not mention subspecies mogilasium .

Based on the original descriptions, recorded distributions and the distinct possibility that morphological and genetic distinctions await discovery, and because it is important to determine with certainty whether or not the nominal species of our predecessors are distinct biological species, we believe it is befitting to return mogilasium and trichorryes to their original species status: Trichoprosopon mogilasium ( Dyar & Knab, 1907) and Trichoprosopon trichorryes ( Dyar & Knab, 1907) , elevated from synonymy with Tr. compressum Lutz, 1905 . Trichoprosopon mogilasium is currently listed as a species in the Encyclopedia of Life; Tr. trichorryes needs to be added to the list.