Limnophyes stagnum Namayandeh, Guerra & Ram 2024, sp. nov.

Limnophyes stagnum Namayandeh, Guerra & Ram sp. nov. Figs 8, 9 Type material. Holotype 1 male; USA, Michigan, Detroit, Palmer Park, Pond A; 42.42766 ° N, 83.11741 ° W; leg. P. L. Hudson; 29. xi. 2023, dep. ARC. Paratypes 2 males, 3 females; same as holotype. Diagnostic characters. Adults of this species can be separated from other Limnophyes by the combination of the following characteristics: Adults with no thoracic lanceolate setae and 2 prescutellars; adult male without humeral setae, female with single humeral setae; male with 3 epimerons, 1 posterior anepisternum II, 1–2 preepisternals anteriorly parallel to antepronotum and close to anapleural suture; female with 2 posterior anepisternals II; 6 epimeron II; 11 preepisternals which 9 anteriorly clustered horizontally, separated from 2 vertical; male antenna with 10 flagellomeres and AR 0.86; female antenna with 4 flagellomere and AR 0.5; male anal point extremely short, almost receded, wide and triangular with apex rounded and gonostylus expanded evenly from base to apex; female with apodeme lobe not distinct; cercus pediform. Description. Male (n = 3, unless otherwise indicated). Total length 1.8–1.9 mm. Wing 0.91–1.1 mm long and 0.3 mm wide. Coloration. Head, thorax, legs, tergites, sternites, and hypopygium blackish brown. Wings and halters grey. Head (Fig. 8 A, B). Antenna with 10 flagellomeres, last flagellomere with 4 sensilla chaetica, groove starts at the apex of the second segment (Fig. 8 A), AR 0.86 (n = 1). Eyes bare, without dorsomedial extension. Temporal setae 1 inner vertical (Fig. 8 B). Tentorium 113–123, 118 μm long. Clypeus triangular, 82–95, 88 μm long and 106–125, 116 μm wide, bearing 8–10, 9 setae, setae 42–71, 56 μm long. Palpal segment lengths (in μm): 38, 36, 58, 54, 83 (n = 1). Thorax (Fig. 8 C). Lanceolate setae absent. Acrostichals 6; dorsocentrals 9–10; prealars 5; scutellars 4 in single row; antepronotals 2; lanceolate humerals absent; 2 prescutellars; epimeron 3; posterior anepisternum II 1; 1–2 preepisternals anteriorly parallel to antepronotum and close to anapleural suture. Wing (Fig. 8 D). Brachiolum with 1 seta. Squama with 2 setae. All veins bare. Costa extension 62 μm long (n = 1). Anal lobe well-reduced. Microtrichia visible at 10 ×. Legs. Fore tibia spur 36–45, 40 μm long, mid tibia spurs 16 and 14 μm long, hind tibia spurs 31 and 24 μm long, hind tibia comb with around 10 spines. Lengths and proportions of legs as in Table 3. Hypopygium (Fig. 8 E). Anal point extremely short, almost receded, wide, and triangular with apex rounded; anal point 6–15, 10 μm long and 14–34, 24 μm wide. Virga bifid and short, 11–12 μm long. Transverse sternapodeme with well-developed oral projections; sternapodeme 75–79, 77 μm long. Phallapodeme 28–40, 34 μm long. Inferior volsella small triangular lobe covered in numerous simple setae. Gonostylus expanded evenly from base to apex, 67–73, 70 μm long; crista dorsalis very narrow. Gonocoxite 90–116, 103 μm long. HR 1.2–1.7, 1.5, HV 2.5–2.9, 2.7. Female (n = 3). Total length 1.7–1.8 mm. Wing 0.96 mm long, 0.38 mm wide. Coloration. Same as the male. Head (Fig. 9 A). Antenna with 4 flagellomeres, last flagellomere with 4 sensilla chaetica, Antennal segments 1–4 (in μm): 75–77, 76; 49, 47, 87, AR 0.5. Eyes bare. Temporal setae 2, including 1 inner vertical and 1 frontal. Tentorium 141–145, 143 μm long. Clypeus triangular, 59 μm long and 46 μm wide, bearing 13 setae, setae 37–59, 47 μm long. Palpal segment lengths (in μm): 46, 32, 52, 54, 75. Thorax (Fig. 9 B). Acrostichals 5; dorsocentrals 8–12, 9 in a single row; prealars 5; scutellars 4 in single row; 1 humerals, non-lanceolate; 2 prescutellars non-lanceolate; 7 antepronotals; 2 posterior anepisternals II; 6 epimeron II; 11 preepisternals, 9 clustered horizontally close to epimeron, 4 horizontally arching close to anapleural suture. Wing (Fig. 9 C). Brachiolum with 1 seta. Squama bare. R with 3–8, 5 setae, R 1 with 4–5 setae; R 4 + 5 with 9–10 setae; other veins bare. Costa extension 50–74, 62 μm. Microtrichia visible at 10 × magnification. Legs. Hind and mid femur with keel. Fore tibia spur 22–23 μm long, mid tibia spur 21 μm long, second one broken; hind tibia missing. Lengths and proportions of legs as in Table 4. Genitalia (Figs 9 D, E). Seminal capsules 62–89, 72 μm long, and 47–90, 71 μm wide, semi-circular; spermathecal very long, with well-developed bulb (Fig. 9 D). Notum 76–113, 92 µm long, notum and ramus 143–191, 165 µm long. Gonapophysis VIII divided into ventrolateral and thin dorsomesal lobe (Fig. 9 D). Apodeme lobe not distinct. Gonocoxite developed, triangular with around 6–9 setae (Fig. 9 E). Tergite IX undivided. Cercus small, pediform, 58–72, 65 µm long, and 42–54, 48 µm wide (Fig. 9 E). Immatures. Unknown. Etymology. The species is named after the habitat where it is found. The word stagnum is Latin, meaning pond or pool. Distribution. Canada (British Columbia, Ontario); USA (Michigan). Remarks. This is a very unusual Limnophyes species; lack of lanceolate setae on both sexes, lack of humeral setae in males, and single humeral setae in females are distinguishing characteristics. However, the Neotropical species Limnophyes brachyarthra (Edwards, 1931) described by Sæther (1990) also lacks lanceolate setae and humerals. The adults of L. stagnum sp. nov. can be easily separated from those of L. brachyarthra based on the number of antennal flagellomere and AR. Additionally, the chaetotaxy of the thorax varies between the two species, and adult males have gonostylus of different shapes and sizes. According to Sæther (1985) the placement of lanceolate humeral setae in relation to the humeral pit varies among Limnophyes species. The lanceolate setae can be in or on the margin of humeral pit, concentrated around or above the pit, or scattered over the humerals. Although the lanceolate setae are missing in L. stagnum sp. nov., the humeral seta of the female is located on the pit, similar to that in L. natalensis. The shape of the hypopygium of the new species also resembles Limnophyes natalensis Kieffer, 1914 as well as Limnopyes difficilis Brundin, 1947. The adult male of the new species can be separated from the adult males of L. natalensis and L. difficilis based on the number of antennal flagellomeres, antennal ratio, lack of lanceolate and humeral setae, number and formation of thoracic setation, and bare squama. The adult female of the new species can be separated from the adult females of L. natalensis and L. difficilis based on the number of humeral setae, number and formation of thoracic setation, bare squama, and size of the notum.

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