Alexeter flavomaculatus Chen, Huang & Shiao, 2025

Chen, Hsuan-Pu, Huang, Chia-Lung & Shiao, Shiuh-Feng, 2025, A taxonomic revision of the genus Alexeter Förster (Hymenoptera, Ichneumonidae, Ctenopelmatinae, Mesoleiini) from Taiwan, with descriptions of six new species, ZooKeys 1250, pp. 315-358 : 315-358

publication ID	https://doi.org/10.3897/zookeys.1250.156835
publication LSID	lsid:zoobank.org:pub:F163B426-20B5-4054-84AD-D739971F25CF
DOI	https://doi.org/10.5281/zenodo.17037829
persistent identifier	https://treatment.plazi.org/id/4AF2797C-5ED4-5B86-89B2-3066B3088AD2
treatment provided by	ZooKeys by Pensoft
scientific name	Alexeter flavomaculatus Chen, Huang & Shiao
status	sp. nov.

Treatment

Alexeter flavomaculatus Chen, Huang & Shiao sp. nov.

Figs 4 A – H View Figure 4 , 10 B View Figure 10 , 11 D – F View Figure 11 , 12 A – C View Figure 12 ; Suppl. material 3 Chinese vernacular name: 黃紋亞力姬蜂

Material examined.

Holotype. Taiwan • 1 ♀; Nantou County, Ren’ai Township, Meifeng ; alt. 2150 m; May. 1984; Malaise Trap; K. S. Lin & K. C. Chou leg.; TARI ( MesoleiYM-F 01 ) . Paratypes. Taiwan • 1 ♂; ibid; 7–9. May. 1984; TARI MesoleiYM-M 01 • 1 ♂; ibid; Apr. 1984; TARI ( MesoleiYM-M 02 ) • 1 ♂; Nantou County, Ren’ai Township, Sanjiaofeng trail ; alt. 2200–2300 m; 11. May. 2024; Sweeping; J. Y. Fan leg.; GenBank: PV 223412 ( COI); NMNS ENT 8951-8 (Mesolei 15) .

Diagnosis.

This species can be distinguished from congeners by the combination of the following characters: smaller ocelli ( OD = 0.15–0.19 mm; OOL / OD = 1.2–1.6); fore wing areolet trapezoid with stalk, receiving 2 m-cu at distal corner (Fig. 10 B View Figure 10 ); fore wing 1 cu-a almost vertical, opposite or slightly distad to M & RS (Fig. 10 B View Figure 10 ); lateromedian longitudinal carinae of propodeum present posteriorly with the area petiolaris opened (Fig. 3 E View Figure 3 ); T 1 2.7–3.5 × its posterior width; S 9 with subtriangular median area weakly sclerotized (Fig. 11 D View Figure 11 ); mesosoma and metasoma generally black, with latero-anterior corners of mesoscutum, ventral subtriangular marking of mesopleuron (enclosing black area), and median markings on tergites behind T 2 yellow (Figs 4 A, D – F View Figure 4 , 12 A – C View Figure 12 ).

This new species is similar to the Asian species A. flaviventris Li & Sun, 2022 , A. albimaculatus Sheng, Sun & Li, 2020 , and A. zangicus Sheng, Sun & Li, 2020 which share black bodies and pale markings on the latero-anterior corners of mesoscutum.

It can be distinguished from A. flaviventris by the following characters: lateromedian longitudinal carinae of propodeum absent on the anterior and median portions (Fig. 4 E View Figure 4 ) (present and combined as single carina medially in A. flaviventris ); metasomal tergites and ventral portion of mesopleuron with yellow markings (Figs 4 A, F View Figure 4 , 12 B View Figure 12 ) (without in A. flaviventris ).

It can also be distinguished from A. albimaculatus by the following characters: face and mandibles yellow (Figs 4 C View Figure 4 , 12 A View Figure 12 ) (face white and mandibles entirely black in A. albimaculatus ); fore and mid legs each with yellow coxae and reddish-brown other part (Fig. 4 A View Figure 4 ) (generally black with white tibiae in A. albimaculatus ); latero-anterior corners of mesoscutum, ventral portion of mesopleuron, and metasomal tergites with yellow markings (Figs 4 A, D, F View Figure 4 , 12 B, C View Figure 12 ) (marking on mesoscutal corners white, other markings absent in A. albimaculatus ); antenna without white band (Fig. 4 A View Figure 4 ) (with white band in A. albimaculatus ); and lateromedian longitudinal carinae of propodeum absent on the anterior and median portions (Fig. 4 E View Figure 4 ) (present in A. albimaculatus ).

Lastly, it can be distinguished from A. zangicus by the following characters: areolet present (Fig. 10 B View Figure 10 ) (absent in A. zangicus ); face and clypeus yellow (Figs 4 C View Figure 4 , 12 A View Figure 12 ) (face black and clypeus yellow in A. zangicus ); truncate ventral margin of clypeus (Figs 4 C View Figure 4 , 12 A View Figure 12 ) (concave in A. zangicus ); metasomal tergites black with yellow markings (Fig. 4 F View Figure 4 ) (generally reddish-brown in A. zangicus ).

Description.

The measurements were based on Taiwanese specimens ( 1 female and 3 males).

Female ( holotype). Head (Figs 4 A – C View Figure 4 , 12 A View Figure 12 ): matt and granulate, HW / HL = 1.8; ocelli normal, with OD = 0.2 mm, POL / OD = 0.8, OOL / OD = 1.4, POL / OOL = 0.6; face matt and granulate, FW / FH = 1.6; clypeus polished and smooth with sparse punctures and subventral median elevation, rounded on ventral margin, CLW / CLH = 2.6; MSL / BMW = 0.5; mandible minutely coriaceous with minute punctures, teeth equal in length; flagellum with 45 segments; average ratio of basal five flagellomeres length 2.5: 1.4: 1.1: 1.2: 1.0.

Mesosoma (Figs 4 A, D, E View Figure 4 , 12 B, C View Figure 12 ): matt and granulate; pronotum with epomia weak, rugose at dorso-anterior corner; mesoscutum with MSSL / MSSW = 1.2, notauli short and indistinct, present near anterior margin; scutellum with SCL / SCW = 1.3, lateral carina absent; epicnemial carina weak, ~ 0.7 × height of mesopleuron; metapleuron with pleural carina and submetapleural carina strong and complete; juxtacoxal carina present posteriorly; propodeum with spiracle circular, maximum axis 1.0 × as minimum axis; anterior and posterior transverse carinae and lateral longitudinal carina absent; lateromedian longitudinal carina absent on anterior and median portions, present on posterior ~ 0.3 with area petiolaris opened anteriorly; average ratio of hind tarsomere length 4.0: 2.0: 1.5: 1.0: 1.0.

Wings (Fig. 10 B View Figure 10 ): fore wing length 8.3 mm; areolet open and trapezoid with stalk 0.5 as long as 2 rs-m, receiving 2 m-cu at distal corner; RMI = 0.7; 1 cu-a almost vertical, opposite or slightly distad to M & RS, with BNI = 0.2. Hind wing length 6.0 mm; NI = 2.2; distal hamuli 6–7.

Metasoma (Fig. 4 F – H View Figure 4 ): matt and granulate, except tergites behind T 2 weakly coriaceous; T 1 3.5 × as long as posterior width, 6.6 × as long as anterior width, 2.3 × as long as length of T 2; T 1 with latero-median carina absent, dorso-lateral carina and ventro-lateral carina strong and complete, spiracle at around middle of T 1, glymma distinct; T 2 0.8 × as long as posterior width, 1.3 × as long as anterior width, gastrocoeli shallow and indistinct, thyridia almost circular; ovipositor sheath 6.0 × as long as its maximum width in lateral view, as long as apical depth of metasoma.

Color (Figs 4 View Figure 4 , 10 B View Figure 10 ): head, mesosoma, and metasoma generally black, and legs generally reddish-brown, except face, dorsal 1 / 2 of clypeus, malar space, mandibles, palpi, dorso-posterior corner of pronotum, latero-anterior corners of mesoscutum, dorso-anterior corner and ventral subtriangular marking (except enclosing area) of mesopleuron, tegula, scutellum, postscutellum, fore and mid coxae and trochanters, dorsal surface of hind coxa, hind second trochanter, median markings on tergites behind T 2 yellow; antenna, marking on ventral 1 / 2 of clypeus, tinged color of tergites behind T 2, ovipositor sheath reddish-brown; ventral side of hind coxa, hind trochanter, and hind femur black. Wings hyaline, veins blackish-brown, and pterostigma reddish-brown.

Male. General structure and color similar to female, except notauli long and distinct, lateromedian longitudinal carinae of propodeum vestigial on median portion, and clypeus completely yellow, subtriangular marking with enclosing black area on ventral mesopleuron more distinct (Fig. 11 A – C View Figure 11 ). Male genitalia with gonostyle tapered and rounded apically, S 9 weakly concave on posterior margin, with subtriangular median area weakly sclerotized (Fig. 11 D – F View Figure 11 ).

HW / HL = 1.8–1.9 (1.8 ± 0.06); OD = 0.15–0.19 (0.17 ± 0.02) mm, POL / OD = 0.5–0.9 (0.7 ± 0.2), OOL / OD = 1.2–1.6 (1.4 ± 0.18), POL / OOL = 0.4–0.6 (0.5 ± 0.09); FW / FH = 1.4–1.8 (1.6 ± 0.17), CLW / CLH = 3.0–4.0 (3.6 ± 0.54), MSL / BMW = 0.52–0.54 (0.52 ± 0.01); flagellum with 43–45 segments; average ratio of basal five flagellomeres length 2.3: 1.3: 1.2: 1.1: 1.0; MSSL / MSSW = 1.2–1.3 (1.3 ± 0.04); SCL / SCW = 1.1–1.2 (1.1 ± 0.07); maximum axis of propodeal spiracles 1.0–1.2 (1.1 ± 0.1) × as minimum axis; average ratio of hind tarsomere length 4.1: 2.2: 1.8: 1.0: 1.2; fore wing length 7.2–7.8 (7.5 ± 0.29) mm; areolet with stalk 0.4–0.6 (0.5 ± 0.1) × as long as 2 rs-m; RMI = 0.7–0.8 (0.8 ± 0.04); BNI = 0.1–0.2 (0.2 ± 0.03); hind wing length 5.2–5.6 (5.4 ± 0.23) mm; NI = 2.0–2.7 (2.4 ± 0.36); distal hamuli 6–7; T 1 2.7–3.1 (2.9 ± 0.16) × as long as posterior width, 6.1–6.6 (6.3 ± 0.29) × as long as anterior width, 1.3–1.6 (1.5 ± 0.11) × as long as length of T 2; T 2 1.2–1.4 (1.2 ± 0.1) × as long as posterior width, 1.6–1.9 (1.7 ± 0.13) × as long as anterior width.

Bionomics.

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

Distribution.

Taiwan ( Nantou).

Etymology.

The specific name flavomaculatus is derived from the Latin words flavo - (yellow) and maculatus (stained or spotted), referring to the yellow markings in the body color pattern of this new species. The name is an adjective.

Remarks.

This new species is assigned to the genus Alexeter based on both morphological characters and molecular phylogeny. It is nested within Alexeter Clade I in the current COI - based phylogeny (Fig. 2 View Figure 2 ). Although the notauli are occasionally indistinct in some individuals (whereas they are typically distinct in Alexeter ), other characters align with the generic definition of Alexeter .