Alexeter monticola 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

Alexeter monticola Chen, Huang & Shiao sp. nov.

Figs 7 A – H , 10 E ; Suppl. material 3 Chinese vernacular name: 山亞力姬蜂

Material examined.

Holotype. Taiwan • 1 ♀; Nantou County, Ren’ai Township, Yuanfeng ; alt. 2700–2800 m; 2. Aug. – 8. Sep. 2005; Malaise Trap (KCN); C. S. Lin & W. T. Yang leg.; NMNS ENT 7392-1403 . Paratypes. Taiwan • 1 ♀; Nantou County, Ren’ai Township, Yuanfeng ; alt. 2700–2800 m; 13. Jun. – 18. Jul. 2001; Malaise Trap (KCN); C. S. Lin & W. T. Yang leg.; NMNS ENT 4229-2746 • 1 ♀; ibid; 8. Sep. – 4. Oct. 2005; NMNS ENT 7393-612 • 1 ♀; ibid; 9. Jul. – 13. Aug. 2002; NMNS ENT 4373-1645 • 2 ♀♀; ibid; 13. Aug. – 10. Sep. 2002; NMNS ENT 4373-491 , NMNS ENT 4373-374 • 1 ♀; ibid; 7. Aug. – 11. Sep. 2001; NMNS ENT 4229-98 • 1 ♀; Nantou County, Ren’ai Township, Tsuifeng ; alt. 2300 m; 1–3. Sep. 1982; Malaise Trap; L. Y. Chou & K. C. Chou leg.; TARI (measure 01) • 2 ♀♀; ibid; Sep. 1984; K. S. Lin & K. C. Chou leg.; TARI (measure 02–03) .

Diagnosis.

This species can be distinguished from congeners by the combination of the following characters: fore wing length longer than 10.0 mm (10.7–12.0 mm); ocelli large ( OD = 0.21–0.29 mm; OOL / OD = 0.5–0.8); POL / OOL = 0.8–1.2; female with flagellum segments 46–52; fore wing areolet triangular with stalk, receiving 2 m-cu at distal corner (Fig. 10 E ); fore wing 1 cu-a vertical and opposite to M & RS (Fig. 10 E ); lateromedian longitudinal carinae of propodeum present posteriorly and forming the area petiolaris opened (Fig. 7 E ); posterior transverse carina absent (Fig. 7 E ); metasomal T 1 3.4–3.9 × its posterior width; head, mesosoma, legs, and metasoma generally yellowish-brown to orange, with mesoscutum having three blackish-brown longitudinal stripes on the lobes (Fig. 7 A, D ).

This new species is most similar to A. clavator , A. hsiaoae sp. nov., and A. mediolobus sp. nov. in body color but can be distinguished by the POL / OOL ratio (0.8–1.2 vs 1.1–1.5 in A. mediolobus 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 (3.4–3.9 vs 2.5–3.1 in A. mediolobus sp. nov., and ~ 3.3 in Chinese A. clavator ), female flagellomere counts (46–52 vs 40–43 in A. mediolobus sp. nov.), color patterns of mesoscutum (three stripes on each lobe vs absent in A. clavator and one stripe on the median lobe in A. mediolobus sp. nov.), gena (orange or yellowish-brown vs yellowish-white in A. hsiaoae sp. nov.), and fore and mid coxae color (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 three brown stripes on the lobes of mesoscutum (stripes absent in these species). A comparative table of 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 ( 10 females).

Female. Head (Fig. 7 A – C ): matt and minutely coriaceous, HW / HL = 1.6–1.8 (1.8, 1.7 ± 0.08); ocelli large, with OD = 0.21–0.29 (0.24, 0.25 ± 0.03) mm, POL / OD = 0.6–0.8 (0.6, 0.7 ± 0.09), OOL / OD = 0.5–0.7 (0.7, 0.7 ± 0.09), POL / OOL = 0.8–1.2 (0.9, 1.0 ± 0.14); face matt and coriaceous, FW / FH = 1.3–1.6 (1.5, 1.5 ± 0.07); clypeus polished and smooth with sparce punctures and subventral median elevation, truncate on ventral margin, CLW / CLH = 3.0–3.8 (3.4, 3.4 ± 0.27); MSL / BMW = 0.4–0.5 (0.4, 0.4 ± 0.03); mandible smooth with sparce punctures, teeth equal in length; flagellum with 46–52 (49) segments; average ratio of basal five flagellomeres length 2.2: 1.3: 1.1: 1.0: 1.0.

Mesosoma (Fig. 7 A, D, E ): matt and granulate; pronotum with epomia absent, weakly and densely carinate at dorso-anterior corner; mesoscutum with MSSL / MSSW = 1.1–1.3 (1.3, 1.2 ± 0.06), notauli distinct on anterior ~ 0.3; scutellum with SCL / SCW = 0.9–1.4 (1.1, 1.2 ± 0.16), lateral carina absent; epicnemial carina strong, ~ 0.5 × height of mesopleuron; metapleuron with pleural carina and submetapleural carina complete; juxtacoxal carina absent; propodeum with spiracle circular or suboval, maximum axis 1.0–1.1 (1.1, 1.1 ± 0.05) × as minimum axis; anterior and posterior transverse carinae absent; lateromedian longitudinal carinae absent on anterior and median portions, present on posterior ~ 0.2 with area petiolaris opened anteriorly; lateral longitudinal carinae vestigial posteriorly; average ratio of hind tarsomere length 4.0: 2.0: 1.6: 1.0: 1.1.

Wings (Fig. 10 E ): fore wing length 10.7–12.0 (10.74, 11.2 ± 0.48) mm; areolet open and triangular with stalk 0.3–0.5 (0.4, 0.4 ± 0.05) as long as 2 rs-m, receiving 2 m-cu at distal corner; RMI = 0.6–1.0 (0.7, 0.7 ± 0.10); 1 cu-a vertical and almost opposite to M & RS, with BNI = 0.1–0.2 (0.1, 0.17 ± 0.03). Hind wing length 8.0–9.0 (8.01, 8.3 ± 0.37) mm; NI = 1.8–3.7 (2.1, 2.3 ± 0.61); distal hamuli 6–9 ( 6 in left and 7 in right wing).

Metasoma (Fig. 7 F – H ): matt and granulate; T 1 3.4–3.9 (3.9, 3.5 ± 0.16) × as long as posterior width, 6.7–8.2 (7.3, 7.5 ± 0.55) × as long as anterior width, 1.4–1.6 (1.4, 1.4 ± 0.06) × as long as length of T 2; T 1 with latero-median carina absent, dorso-lateral carina present on basal ~ 0.1 and apical 0.3, ventro-lateral carina complete, spiracle at around basal 0.4, glymma distinct; T 2 1.2–1.5 (1.5, 1.3 ± 0.08) × as long as posterior width, 1.9–2.4 (2.3, 2.1 ± 0.17) × as long as anterior width, gastrocoeli indistinct, thyridia long ellipse; ovipositor sheath 2.3–3.3 (2.8, 2.8 ± 0.26) × as long as its maximum width in lateral view, shorter than apical depth of metasoma.

Color (Fig. 7 , 8 E ): head, mesosoma, legs, and metasoma generally yellowish-brown to orange, except face, clypeus, and malar space yellowish-white; frons (in most paratypes) and three longitudinal stripes on lobes of mesoscutum blackish-brown; metasoma in some paratypes brown. Wings hyaline, veins yellowish-brown, and pterostigma pale yellowish-brown.

Male. Unknown.

Bionomics.

This species has been collected from mountainous areas in Taiwan above 2300 m by Malaise trap. Hosts are unknown.

Distribution.

Taiwan ( Nantou).

Etymology.

The specific name monticola is derived from Latin, meaning existing or having a habitat in or on mountains. The name is an adjective.

Remarks.

Morphological variations in the color of the frons and metasoma were observed within the type series, with some paratypes exhibiting blackish-brown frons and metasoma. The amplification of COI sequences in this species failed in this study.

Despite this new species sharing slightly overlapping OOL / OD ratios, flagellomere counts, and distal hamuli counts with its most similar species, A. hsiaoae sp. nov., the diagnostic color patterns (gena, vertex, fore and mid coxae) are clearly distinct between the two species. A. hsiaoae sp. nov. exhibits a stable coloration across multiple distant high-mountain localities, including Mt. Nanhu, Mt. Shueshan, and Mt. Antungchunshan. In contrast, A. monticola sp. nov. shows minor color variation on the frons within a population collected from a single locality but remains distinguishable based on the aforementioned color patterns. Additionally, their elevational distribution does not overlap among our samples. Therefore, we consider A. monticola sp. nov. to be an independent species from A. hsiaoae sp. nov.

Figures

Figure 7. Alexeter monticola sp. nov., holotype, female (NMNS ENT 7392-1403). A. Lateral habitus; B. Head in dorsal view; C. Head in anterior view; D. Mesoscutum in dorsal view; E. Propodeum in dorsal view; F. Metasomal tergites 1 and 2 in dorsal view; G. Metasomal tergite 1 in lateral view; H. Ovipositor.

Figure 8. Alexeter pseudozangicus sp. nov., holotype, female (TARI). A. Lateral habitus; B. Head in dorsal view; C. Head in anterior view; D. Mesoscutum in dorsal view; E. Propodeum in dorsal view; F. Metasomal tergites 1 and 2 in dorsal view; G. Metasomal tergite 1 in lateral view; H. Ovipositor.

Figure 10. Wings of the Taiwanese Alexeter species. A. A. shakojiensis; B. A. flavomaculatus sp. nov.; C. A. hsiaoae sp. nov.; D. A. mediolobus sp. nov.; E. A. monticola sp. nov.; F. A. pseudozangicus sp. nov.; G. A. rufispeculus sp. nov.