Simulium (Disculter) Molina & Gil-Azevedo 2021, subgen. nov.
Creators: name: Molina, Óscar S.
name: Gil-Azevedo, Leonardo H.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Simuliidae
Simulium

description: Simulium (Disculter) subgen. nov.
urn:lsid:zoobank.org:act: E5A8F7C6-7B96-4F7F-A54D-9CBBB160EE41
Figs 31–32, 48–49, 69–70, 89–90, 148–149
Type species
Simulium oviedoi Ramírez-Pérez, 1971.
Diagnosis
Female
Scutum black; scutal pattern present. Cibarium unpigmented anteromedially and unarmed. Tarsal claw with subbasal tooth of about half of claw length. Hypoginial valves subtriangular, shorter than sternite VIII width, forwardly directed. Anal lobe subrectangular and shorter than the cercus base width (Figs 31–32).
Male
Ventral plate (Figs 48–49) with sub-equal width and length, not notched; lateral shoulders absent; posteromedian process absent. Gonocoxite length equal to width, with base almost equal in width than gonostylus width at their point of intersection (Figs 69–70). Gonostylus cylindrical, with medial region equal in width than basal region; longer than gonocoxite, with acute apex and apical spinule (Figs 69– 70). Parameres with both distinctly large and small accessory spines.
Pupa
Cocoon aperture upward directed, separated from substratum, not corbicular (Figs 89–90). Gills shorter than pupa body, with trunk development, and base enclosed by cocoon anterior margin; with six filaments arranged in different planes (tridimensional); filaments cylindrical, with blunt apices concolorous with rest of gill; inferior branch multibranched. Thoracic trichomes present or absent.
Larva (last instar)
Cephalic apotome spots insertion area not pigmented. Postocciput not extended over the cervical sclerites. Antenna shorter than labral fan stalk, without secondary annulations. Mandibles with preapical teeth shorter than apical tooth; two mandibular serrations of same sizes. Postgenal cleft triangular; postgenal bridge length nearly equal than hypostomal length (Figs 148–149). Hypostomal anterior margin straight; hypostomal teeth extended beyond anterior margin of ventral wall of hypostoma; medial tooth as prominent as lateral ones; lateral serrations well-developed, sharp; paralateral teeth present. Body glabrous. Abdomen gradually expanding posteroventrally to last segments, then abruptly contracting to posterior proleg. Anal sclerite not encircling base of posterior proleg. Posterior portion of abdomen without sclerotized accessory plates. Without 1+1 ventral tubercles. Rectal papillae with three multi-branched lobes.
Etymology
The name Disculter derives from Latin prefix ‘ dis ’, meaning 'apart’, plus the Latin ' culter ’, meaning 'knife or razor’, in reference to the gonostylus shape, which differs from those of other related subgenera, such as S. (Trichodagmia) and S. (Hemicnetha). The gender is masculine.
Species
Simulium oviedoi Ramírez-Pérez, 1971
S. rivasi Ramírez-Pérez, 1971
Remarks
Oviedoi species-group in Coscarón (1987) (not included in any Simulium subgenera). Oviedoi speciesgroup of Simulium (Hemicnetha) in Coscarón & Coscarón-Arias (2007). As part of the Orbitale species-group of S. (Hemicnetha) in Shelley et al. (2010). As part of the Bicoloratum species-group of S. (Psilopelmia) in Hernández (2011).
Simulium oviedoi and S. rivasi were first described and included in S. (Hemicnetha) by Ramírez-Pérez (1971). Coscarón (1987) created the group Oviedoi, not including it in any Simulium subgenus, but regarding it as close to S. (Hemicnetha) based on the general aspect of the adult and last instar larva. Coscarón & Coscarón-Arias (2007) placed Oviedoi as a species-group within S. (Hemicnetha) based on the female cibarium, nudiocular triangle, frontoclypeal base, basal section of the Radius, pupal cocoon, and shape of pupal gill. Even these authors considered that S. (Hemicnetha) offered the closest fit for S. oviedoi and S. rivasi, and pointed out that the female and male genitalia of the Oviedoi speciesgroup differ from those of most other species of S. (Hemicnetha). Shelley et al. (2010) transferred both species from S. (Hemicnetha) to the Orbitale species-group of S. (Trichodagmia) (sensu Shelley et al. 2010), but did not explain the reason for this taxonomic change. Hernández (2011) transferred them to the Bicoloratum species-group of S. (Psilopelmia) based on the female cibarium, male ventral plate shape, gonocoxite/gonostyle length ratio, and larval hypostomal teeth. Gil-Azevedo & Coscarón (2020) confirmed that Oviedoi failed to group with S. (Psilopelmia) and recovered it as closer to S. (Hemicnetha).
According to our analysis, Oviedoi is close to the clade [(S. (Anasolen) + S. (Freemanellum) + S. (Hemicnetha) + S. (Trichodagmia)] (Fig. 1, node 9), but did not fit in any of these groups or in any other Neotropical Simulium subgenus. Therefore, we here propose a new subgenus, S. (Disculter) subgen. nov. (Fig. 1, node 10) to accommodate the species in this group.
Both species are almost identical and can be differentiated only by the trichomes and tubercles of the pupal frontoclypeus and thorax. Simulium oviedoi has trichomes with 3–5 ramifications and spinous tubercles, whereas S. rivasi to does not have trichomes and has rounded tubercles.
Distribution
The subgenus is endemic to the state of Mérida, Venezuela (Adler 2020).
description: Published as part of Molina, Óscar S. & Gil-Azevedo, Leonardo H., 2021, Simulium (Trichodagmia) (Diptera, Simuliidae) phylogeny revisited: the Neotropical and Afrotropical connection, pp. 80-119 in European Journal of Taxonomy 773 on pages 110-112, DOI: 10.5852/ejt.2021.773.1517, http://zenodo.org/record/5542069