Chelonus (Megachelonus) arabicus Soliman & Gadallah, 2025

Soliman, Ahmed M., Al Dhafer, Hathal M. & Gadallah, Neveen S., 2025, First record of the subgenus Megachelonus Baker, 1926 (Hymenoptera: Braconidae: Cheloninae, genus Chelonus Panzer, 1806) for the Afrotropical region (southwestern region of Saudi Arabia), with the description of a new species, Zootaxa 5575 (1), pp. 159-166 : 160-163

Chelonus (Megachelonus) arabicus Soliman & Gadallah , sp. nov.

Figs 1A‒C , 2A‒E , 3A‒E

Material examined: Holotype ♀, Saudi Arabia, Jazan, Ad-Dair, Jabal Al-Ma’atoub (17°21’22”N 43°11’58”E, alt. 1696 m), 24.iv‒4.ix.2024, MT, leg. Ahmed M. Soliman [ KSMA].

Description. The holotype female body length: 5.3 mm (excluding carapace apical teeth); length of fore wing: 3.2 mm.

Head ( Fig. 2A‒D ). Densely setose on occiput, ocellar triangle and clypeus; antenna inserted in the middle of face, with 16 antennomeres, flagellomeres long, thin and slender, with F6 and following distinctly flattened below; scape slightly concave ventrally, 2.5× as long as its width; F1 5.3× as long as wide, slightly longer than F2 (1.14×), F2 4.6× as long as wide, penultimate flagellomere 2.6× as long as wide, slightly shorter than last flagellomere; head in dorsal view transverse, transversely strigose behind ocelli and on temple; face distinctly depressed above antennal sockets and below ocelli (when seen in lateral view), longitudinally strigate laterally, and transversely striated medially behind antennal bases, depression with longitudinal median carina extended slightly behind antennal sockets; gena shiny, with dense, fine longitudinal striations; occipital carina thin, complete; eyes moderately protruding, 2.1× as long as temple; ocelli arranged in an isosceles triangle, with base distinctly longer than lateral sides (2.3×); OOL 1.4× POL; clypeus semielliptical, finely punctate in curved rows; mandible twisted, bidentate, with inner tooth distinctly shorter than outer tooth; malar space 1.35× as long as basal width of mandible.

Mesosoma ( Figs 2E , 3A, B ). Pronotal anterior face extremely short, vertical and coarsely rugose, pronotal side rugose-foveolate; mesoscutum in lateral view 0.8× as long as its height and distinctly elevated above level of pronotum, forming a right angle with pronotum, rather flat dorsally, distinctly depressed postero-medially (with longitudinal median faint carina on depressed portion), densely irregularly foveolate-rugose, granulated in between, except postero-laterally being finely densely punctate; notauli absent; scutellum distinctly elevated above level of mesoscutum, rugose except postero-laterally being smooth, with seven short longitudinal carinae anteriorly (occupying about 0.25× of scutellar length), scutellar sulcus straight; mesopleuron foveolate-rugose, that are dense and coarse above, then punctate, punctures arranged in curved rows, with dull interspaces; propodeum with a transverse carina separating dorsal surface and posterior declivity, dorsal surface foveolate-rugose, posterior declivity concave and punctate, punctures arranged in separated longitudinal rows, with shiny interspaces; mesosterum densely foveolate.

Fore wing ( Fig. 3C ). Its length 3.4× its maximum width; pterostigma swollen, 2.7× as long as its width, 1.28× as long as vein 1-R1; vein SR1 entirely sclerotized, straight, short and not reaching wing apex; vein r arising nearly from middle of pterostigma, inclivous, about as long as vein 3-SR and 0.8× as long as vein 2-SR; 1-CU1: cu-a: 2-CU1 = 6: 9: 16; vein 1-M distinctly curved behind, 1.5× vein m-cu; vein M+Cu1 not straight, distinctly curved, membranous at base; vein cu-a postfurcal.

Legs ( Fig. 1B, C ). Fore tarsus 1.15× as long as fore tibia; hind coxa finely transversely striated dorsally; hind femur shiny, finely alutaceous; hind femur, hind tibia, and basitarsus 3.35, 5.0, 4.8× as long as their widths, respectively; hind tibia widened apically; inner hind tibial spur 0.4× as long as hind basitarsus.

Metasoma ( Figs 1A , 3D, E ). Carapace in dorsal view 2.15× as long as its maximum width, with medio-basal swelling and two dorso-lateral oblique longitudinal carinae basally; densely coarsely foveolate rugose at basal third, becoming finer at posterior two-thirds; longitudinally superficially rugose along the ivory spots; carapace without lamella, with two triangular pointed spines apico-ventrally, separated from each other by a distance equal 0.8× spine length; carapace finely setose throughout, sharply edged laterally; ovipositor shortly exerted from metasomal apex, about 0.45× as long as carapace; ovipositor sheath broken.

Color ( Figs 1A‒C , 2A, C, D , 3C‒E ). Body black, carapace with two large sub-basal, quadrate ivory spots; legs with coxae and trochanters black: fore leg with femur (except pale brown apex) black, tibia and tarsus (except dark last tarsomere) pale brown; mid leg with most of femur black, tibia pale brown, whitish medially, basitarsus whitish, remaining tarsomeres pale brown; hind leg with femur and apical half of tibia black, basal half of tibia and basitarsus whitish, remaining tarsomeres dark brown to black; tibial spurs whitish; tegula blackish brown; mandible reddish, black basally and apically; eyes and ocelli dark reddish brown; ovipositor pale red to yellow, remaining part of ovipositor sheath dark brown. Wings hyaline, with dark brown pterostigma and veins (except pale basal part of veins M+CU1); parastigma pale brown to yellow.

Distribution: So far Saudi Arabia (Jazan).

Etymology: The new species is named in reference to the region where the specimen was collected.

Comments. This is the first record of the subgenus Chelonus (Megachelonus) in the Afrotropical region, and the Arabian Peninsula. Based on Zhou et al. (2022a), the female of the new species belongs to C. ( Megachelonus ) for the following combination of characters: head transverse ( Fig. 2B ); apical half of flagellomeres flattened above ( Fig. 2D ); face and gena striate to reticulate ( Fig. 2A, C ); clypeus semielliptical ( Fig. 2A ); eye ovoid in lateral view ( Fig. 2C ); mesoscutum foveolate-rugose ( Fig. 2E ); scutellum distinctly elevated above mesoscutum level, with same sculpture as mesoscutum but closer ( Figs 2E , 3A ); propodeum with transverse carina separating dorsal surface from its posterior declivity, with postero-lateral tubercles ( Fig. 3A ); carapace with two ventro-apical spinelike processes ( Fig. 3D, E ).

The new species described here somewhat resembles the Indian species Chelonus (Megachelonus) sahyadriensis Ranjith & Priyadarsanan, 2023 . Based on the key of Ranjith & Priyadarsanan (2023: 470, couplet 3): it agrees with female C. sahyadriensis in having 16 antennomeres ( Fig. 2D ); carapace with large whitish (but not yellowish) spots laterally ( Fig. 3C ); and apex of carapace with two of relatively long spines ( Fig. 3C ). However, it differs from C. sahyadriensis in several aspects: OOL 1.4× POL (in C. sahyadriensis, OOL 1.1× POL)); notauli absent ( Fig. 2E ) (in C. shyadriensis , notauli present, impressed as large pits)); carapace with a baso-median swelling and two midlongitudinal oblique carinae basally ( Figs 2E , 3D ) (in C. sahyadriensis , swelling and carinae absent (see Ranjith & Priyadarsanan, 2023, fig. 15c)); antennal flagellomeres conspicuously very long and slender in the new species ( Fig. 2D ) (in female C. sahyadriensis , flagellomeres moderately long (see Ranjith & Priyadarsanan, 2023, fig. 14A)); fore wing hyaline throughout ( Fig. 3C ) (in C. sahyadriensis , fore wing infuscate subapically)); hind femur, hind tibia, and basitarsus 3.35, 5.0, 4.8× as long as their widths, respectively (in C. sahyadriensis , hind femur, hind tibia, and basitarsus 3.1, 4.2, 4.4× as long as their widths, respectively); carapace with two lateral subbasal whitish spots, distinctly distant from base ( Fig. 3D ) (in female C. sahyadriensis , yellowish spots are present baso-laterally (see Ranjith & Priyadarsanan, 2023, fig. 15c)); gena entirely bare, shiny ( Fig. 2C ) (in female C. sahyadriensis , head generally densely covered with setae throughout (see Ranjith & Priyadarsanan, 2023, fig. 14C, D)); body sculpturing is different in both species especially meososcutum, scutellum, propodeum, mesopleuron and carapace; occiput is obviously upwardly concave in the new species ( Fig. 2B ) (in the female of C. sahadriensis , occiput is nearly straight to slightly concave (see Ranjith & Priyadarsanan, 2023, fig. 14C)); color of legs vary in both species; ventro-apical spines of carapace are parallel-sided, separated by a distance equal to 0.8× spine length in our new species ( Fig. 3D ) (in female C. sahyadriensis , spines are divergent distally (not parallel), separated by a distance equal to half spine length (see Ranjith & Priyadarsanan, 2023, fig. 15C, E)); body length 5.3 mm (in C. sahyadriensis , body length 6.1 mm).

Figures

FIGURE 1A‒C. Chelonus (Megachelonus) arabicus Soliman & Gadallah (Female holotype). (A‒C) Habitus, dorsal, lateral & ventral views, respectively.

FIGURE 2A‒E. Chelonus (Megachelonus) arabicus Soliman & Gadallah (Female holotype). (A & B) Head, frontal & dorsal views, respectively (C) Head, pronotum & mesoscutum (part), lateral view (D) Antenna (E) Mesosoma & metasoma (basal part), dorsal view.

FIGURE 3A‒E. Chelonus (Megachelonus) arabicus Soliman & Gadallah (Female holotype). (A) Scutellum, metanotum & propodeum, dorsal view (B) Mesonotum, lateral view (C) Fore wing (D & E) Metasoma, dorsal & lateral views, respectively.