Diamesa sahandensis Namayandeh et Ibrahimi, 2024

Diamesa sahandensis Namayandeh et Ibrahimi , sp. nov.

urn:lsid:zoobank.org:act:9C5D7D9E-BC1D-481C-933D-A50F7672E200

Fig. 2 View FIGURE 2

Type material. Holotype: male; Iran, East Azerbaijan Province, Central Iranian Range, Kandovan Village, near Sahand Volcano, small stream with sparse high vegetation , 37.7915764˚N, 46.250588˚E; elev. 2254 m; 12.vi.2022; leg. H. Ibrahimi; dep. ROM.

Etymology. The new species is named after the nearby Sahand Volcano, where it was collected. The Latin suffix “ ensis ” denotes the location.

Diagnosis. D. sahandensis sp. nov. adult male can be separated from related species based on the following combination of characters: AR 0.92; apex of tergite IX protuberance with small lobed projection; anal point short without apical peg, apex rounded; superior volsella (basal plate) well-developed with a large pedestal bearing robust, spine-like setae; inferior volsella (medial field) club-shaped, on a long stalk, bearing numerous simple, fine setae, increasing in length apically; gonostylus long and curved, with a basiventral projection bearing fine setae; ventral surface of gonostylus with long, fine setae.

Description

Adult male (n = 1). Total length 3.7 mm. Wing length 2.5 mm, wing width 0.8 mm. TL/WL 1.5.

Coloration. Head, thorax, legs, and abdomen dark brown. Wings greyish brown.

Head ( Fig. 2A–B View FIGURE 2 ).Antenna with 13 flagellomeres and slightly reduced plume, last flagellomere with 1 subapical seta 32 μm long, and 4 sensilla chaetica; AR 0.92 ( Fig. 2A View FIGURE 2 ). Eyes hairy, with short wedge-shaped dorsomedial extension. Temporal setae 16, including 6 postoculars, 2 inner verticals, 2 outer verticals, and 6 orbitals. Tentorium 199 μm long. Clypeus squared, 101 μm long and 121 μm wide; bearing 6 setae, 76–82, 79 μm long. Palpomere lengths (in μm): 90; 81; 123; 142; 178. Palpomere 3 distally with a sensilla capitata, 12 μm in diameter ( Fig. 2B View FIGURE 2 ), sensilla chaetica not detectable. HW/PL 0.94.

Thorax ( Fig.2C View FIGURE 2 ).Achrostichals absent;dorsocentrals 13, mostly uniserial; prealars4; scutellars17.Antepronotum with 6 ventrolateral setae.

Wing ( Fig. 2D View FIGURE 2 ). Brachiolum with 3 setae; R with 14 setae; R 1 with 12 setae; R 4+5 with 2 setae; alula bare; squama with 20 setae. Costa extension 67 μm long. Anal lobe squared. RM /MCu 3.3; VR 0.72. Microtrichia visible at 40 × magnification.

Legs. Spur of fore tibia 68 μm long; spurs of mid tibia 50 and 42 μm long; spurs of hind tibia 73 and 39 μm long. Hind tibial comb with 14 setae. Psuedospurs on tarsal segments 1–2 of foreleg and 1–3 on mid and hindleg. Lengths and proportions of legs as in Table 1 View TABLE 1 .

Hypopygium ( Figs. 2E–I View FIGURE 2 ). Tergite IX with 8 setae on each side located on protuberance, apex of protuberance with small lobed projection. Anal point short, 47 μm long, and 29 μm wide at the base, without apical peg, apex rounded ( Fig. 2E View FIGURE 2 ). Gonocoxite 401 μm long. Superior volsella (basal plate) well-developed with a large pedestal (stalk) 71 μm long, 47 μm wide at the base, and 33 wide at the apex, bearing 20 robust, spine-like setae, 16–27, 22 μm long ( Fig. 2F–G View FIGURE 2 ). Inferior volsella (medial field) club-shaped, on a long stalk, 155 μm long and 36 μm wide at the base, with numerous simple, fine setae 25–34, 31 μm long, microtrichia are present on ventral surface ( Fig. 2F View FIGURE 2 ). Transverse sternapodeme crescent shaped, 112 μm wide and 35 μm long; oral projection weak. Phallapodeme 104 μm long. Aedeagal lobe 129 μm long. Gonostylus 308 μm long, curved, with a basiventral projection bearing 6 apical setae, 10–25, 16 μm long; ventral surface of gonostylus with long, fine setae 23–35 μm long, dorsal surface with shorter setae 5–16, 10 μm long; megaseta 12 μm long ( Fig. 2E–F & H–I View FIGURE 2 ). HR 1.3, HV 1.2.

Female and immatures. Unknown

Remarks. D. sahandensis sp. nov. belongs to the latitarsis group based on the shape of the gonostylus, inferior volsella, the anal point, and the presence of protuberance on tergite IX (see Kownacki & Kownacka 1973; Montagna et al. 2016b; Serra-Tosio 1968). Within this group, it most closely resembles the newly discovered species Diamesa achipseensis Makarchenko, Semenchenko et Palatov, 2024 , and Diamesa caucasica Kownacki et Kownacka, 1973 . D. sahandensis can be distinguished from these related species by the characteristics of hypopygium, including the shape and size of sternapodeme, superior volsella, gonostylus, and the presence of a long inferior volsella. D. sahandensis sp. nov., D. achipseensis , and D. caucasica can be distinguished from other species in this group based on the shape and reduced size of the anal point. Additionally, D. sahandensis sp. nov. and D. caucasica have inner appendages (projections) on their gonostylus, which is distinguishable from other members of this group. Makarchenko et al. (2024) have listed some relevant characteristics in a table to separate D. achipseensis from D. caucasica . Using their table with some additions and modifications, we provided relevant characters to separate the three related species ( Table 2 View TABLE 2 ).