Alexeter mediolobus Chen, Huang & Shiao, 2025

Alexeter mediolobus Chen, Huang & Shiao sp. nov.

Figs 6 A – H View Figure 6 , 10 D View Figure 10 , 11 J – L View Figure 11 ; Suppl. material 3 Chinese vernacular name: 中褐亞力姬蜂

Material examined.

Holotype. Taiwan • 1 ♀; Hualien County, Jian Township, Ci’en – Bilu Giant Tree ; alt. 2000 m; 27. May. 2020; Light Trap; C. L. Huang & L. H. Wang leg.; GenBank: PV 223410 ( COI); TARI (Mesolei 07) . Paratypes. Taiwan • 1 ♀; Nantou County, Ren’ai Township, Meifeng, Tai- 14 A highway 14.7 K , 24.092463 ° N, 121.175501 ° E (DD); alt. 2180 m; 10. May. 2024; Light Trap; H. - P. Chen leg.; GenBank: PV 223411 ( COI); NMNS ENT 8951-7 (Mesolei 16) GoogleMaps • 1 ♀; Nantou County, Ren’ai Township, Meifeng ; alt. 2150 m; Jun. 1984; Malaise Trap; K. S. Lin & K. C. Chou leg.; TARI (measure 01) • 3 ♀♀; ibid; May. 1984; TARI (measure 02–04) • 1 ♂; ibid; 22. May. 1984; TARI (measure 05) • 1 ♂; Nantou County, Ren’ai Township, Meifeng ; 6–26. Apr. 1997; C. S. Lin & W. T. Yang leg.; NMNS ENT 3028-591 .

Diagnosis.

This species can be distinguished from congeners by the combination of the following characters: fore wing length usually shorter than 10.0 mm ( 7.7–10.1 mm); ocelli large ( OD = 0.20–0.27 mm; OOL / OD = 0.5–0.7); POL / OOL = 1.1–1.5; female with flagellum segments 40–43; fore wing areolet trapezoid with stalk, receiving 2 m-cu at distal corner (Fig. 10 D View Figure 10 ); fore wing 1 cu-a almost vertical and opposite to M & RS (Fig. 10 D View Figure 10 ); lateromedian longitudinal carinae of propodeum present posteriorly with the area petiolaris almost closed (Fig. 6 E View Figure 6 ); posterior transverse carina present (Fig. 6 E View Figure 6 ); T 1 2.5–3.1 × its posterior width; head, mesosoma, legs, and metasoma generally brown to yellowish-brown, with mesoscutum having single blackish-brown longitudinal stripe on the median lobe (Fig. 6 A, D View Figure 6 ).

This new species is most similar to A. clavator , A. hsiaoae sp. nov., and A. monticola sp. nov. in body color but can be distinguished from them by the POL / OOL ratio (1.1–1.5 vs 0.8–1.1 in A. hsiaoae sp. nov. and 0.8–1.2 in A. monticola sp. nov.), female OOL / OD ratio (0.5–0.7 vs 0.7–0.9 in A. hsiaoae sp. nov.), length-to-posterior-width ratio of T 1 (2.5–3.1 vs 3.1–4.3 in A. hsiaoae sp. nov., 3.4–3.9 in A. monticola sp. nov., and ~ 3.3 in Chinese A. clavator ), female flagellomere counts (40–43 vs 46 in A. hsiaoae sp. nov. and 46–52 in A. monticola sp. nov.), color patterns of mesoscutum (one stripe on the median lobe vs absent in A. clavator and three stripes on each lobe in A. hsiaoae sp. nov. and A. monticola sp. nov.), gena (brown vs yellowish-white in A. hsiaoae sp. nov. and sometimes orange in A. monticola sp. nov.), and fore and mid coxae (yellowish-brown vs yellowish-white in A. hsiaoae sp. nov.).

This new species can also be distinguished from other yellowish- and reddish-brown species A. nebulator , A. gracilentus , and A. luteifrons by having yellowish-brown head (black in these species) and the blackish-brown stripe on the median lobe of mesoscutum (yellowish-brown in these species). A comparative table of the measurements, ratios, and colors of this new species and other yellowish- or reddish-brown Alexeter species are provided in Suppl. material 3.

Description.

The measurements are based on Taiwanese specimens ( 6 females and 1 male).

Female. Head (Fig. 6 A – C View Figure 6 ): matt and minutely coriaceous, HW / HL = 1.7–2.1 (1.7, 1.9 ± 0.12); ocelli large, with OD = 0.20–0.27 (0.27, 0.25 ± 0.03) mm, POL / OD = 0.6–0.7 (0.6, 0.7 ± 0.05), OOL / OD = 0.5–0.7 (0.5, 0.5 ± 0.06), POL / OOL = 1.1–1.5 (1.1, 1.2 ± 0.13); face matt and minutely coriaceous, FW / FH = 1.4–1.6 (1.5, 1.5 ± 0.08); clypeus matt and evenly punctate with subventral median elevation, truncate or slightly concave on ventral margin, CLW / CLH = 3.0–3.5 (3.5, 3.2 ± 0.19); MSL / BMW = 0.3–0.4 (0.3, 0.3 ± 0.04); mandible densely punctate in dorsal surface, teeth equal in length; flagellum with 40–43 (43) segments; average ratio of basal five flagellomeres length 2.2: 1.2: 1.1: 1.1: 1.0.

Mesosoma (Fig. 6 A, D, E View Figure 6 ): matt and granulate; pronotum with epomia absent, carinate at dorso-anterior corner; mesoscutum with MSSL / MSSW = 1.1–1.2 (1.1, 1.2 ± 0.06), notauli short, distinct near anterior margin; scutellum with SCL / SCW = 1.0–1.4 (1.4, 1.3 ± 0.15), lateral carina present at base; epicnemial carina strong, ~ 0.7 × height of mesopleuron; metapleuron with pleural carina and submetapleural carina complete; juxtacoxal carina present posteriorly; propodeum with spiracle suboval, maximum axis 1.0–1.2 (1.0, 1.1 ± 0.08) × as minimum axis; anterior transverse carina absent; posterior transverse carina present medially; lateromedian longitudinal carinae absent on anterior and median portions, present on posterior ~ 0.2 with area petiolaris almost closed; lateral longitudinal carinae weak; average ratio of hind tarsomere length 3.9: 2.1: 1.6: 1.0: 1.2.

Wings (Fig. 10 D View Figure 10 ): fore wing length 7.7–10.1 (10.12, 9.4 ± 0.84) mm; areolet open and trapezoid with stalk 0.3–0.4 (0.3, 0.3 ± 0.05) as long as 2 rs-m, receiving 2 m-cu at distal corner; RMI = 0.6–0.7 (0.7, 0.6 ± 0.05); 1 cu-a almost vertical and opposite to M & RS, with BNI = 0.1–0.2 (0.1, 0.1 ± 0.04). Hind wing length 5.6–7.4 (7.39, 6.8 ± 0.6) mm; NI = 1.9–2.8 (2.4 ± 0.32); distal hamuli 6–8 (6).

Metasoma (Fig. 6 F – H View Figure 6 ): matt and coriaceous; T 1 2.5–3.1 (2.8, 2.9 ± 0.22) × as long as posterior width, 5.8–8.0 (7.7, 7.0 ± 0.91) × as long as anterior width, 1.4–1.5 (1.5, 1.5 ± 0.03) × as long as length of T 2; T 1 with latero-median carina absent, dorso-lateral carina present on anterior 0.1 and posterior 0.2, ventro-lateral carina complete, spiracle at around middle of T 1, glymma distinct; T 2 0.9–1.3 (1.1, 1.2 ± 0.14) × as long as posterior width, 1.4–2.1 (1.8, 1.8 ± 0.22) × as long as anterior width, gastrocoeli indistinct, thyridia indistinct and circular; ovipositor sheath 2.7–5.5 (3.5, 3.5 ± 1.02) × as long as its maximum width in lateral view, shorter than apical depth of metasoma.

Color (Fig. 6 View Figure 6 , 10 D View Figure 10 ): head, mesosoma, legs, and metasoma generally brown, except face, dorsal 0.7 of clypeus, malar space, gena, mandible base, and dorso-posterior corner of pronotum yellowish-white; palpi, pronotum, dorso-anterior corner and speculum of mesopleuron, fore and mid coxae, and all trochanters and tarsi pale yellowish-brown; frons, vertex, median lobe of mesoscutum in anterior 1 / 2, lateral sides of scutellum blackish-brown. Wings hyaline, veins blackish-brown, pterostigma pale yellowish-brown.

Male. General structure and color similar to female. Male genitalia with gonostyle tapered and rounded apically, S 9 weakly concave on posterior margin, completely sclerotized (Fig. 11 J – L View Figure 11 ).

HW / HL = 1.9; OD = 0.25 mm, POL / OD = 0.6, OOL / OD = 0.5, POL / OOL = 1.3; FW / FH = 1.5, CLW / CLH = 3.0, MSL / BMW = 0.4; flagellum segments broken; average ratio of basal five flagellomeres length 2.2: 1.3: 1.1: 1.2: 1.0; MSSL / MSSW = 1.1; SCL / SCW = 1.2; maximum axis of propodeal spiracles 1.1 × as minimum axis; average ratio of hind tarsomere length 3.7: 2.1: 1.6: 1.0: 1.3; fore wing length 8.9 mm; areolet with stalk 0.1 × as long as 2 rs-m; RMI = 0.3; BNI = 0.1; hind wing length 6.6 mm; NI = 1.9; distal hamuli 6; T 1 2.9 × as long as posterior width, 8.9 × as long as anterior width, 1.5 × as long as length of T 2; T 2 1.3 × as long as posterior width, 1.7 × as long as anterior width.

Bionomics.

This species has been collected from mountainous areas in Taiwan above 2000 m by Malaise trap or light trap. Hosts are unknown.

Distribution.

Taiwan ( Hualien and Nantou).

Etymology.

The specific name mediolobus is derived from the Latin medio - (meaning medial) plus lobus (meaning lobe). It refers to the median lobe of mesoscutum in this species with a distinct blackish-brown marking. The name is an adjective.

Remarks.

In dried specimens of this new species, the lateral lobes of the mesoscutum appear darker than in fresh specimens, which can sometimes lead to misinterpretation as longitudinal stripe patterns. It is nested within Alexeter Clade I in the current COI - based phylogeny (Fig. 2 View Figure 2 ). Endosymbiont co-amplification was observed in this species when amplifying the COI - 5 P region of the COI gene using the LCO 1490 / HCO 2198 primer pair or other primers targeting the same binding site, resulting in noisy chromatograms. Successful amplification of COI sequences was achieved using the primer pair C 1 - J- 1718 / C 1 - N- 2329 ( Rousse et al. 2016).