Sclerodermus alternatusi Yang, 2024

Yang, Zhongqi, Wang, Xiaoyi, Duan, Zhaoyao, Zhang, Yanlong, Yi’nanZhang, Cao, Yi’nanZhang Liangming & Wei, Ke, 2024, Sclerodermus alternatusi (Hymenoptera: Bethylidae), a new species from China, parasitizing Monochamus alternatus (Coleoptera: Cerambycidae), Zoological Systematics 49 (3), pp. 258-266 : 260-265

publication ID	https://doi.org/ 10.11865/zs.2024301
publication LSID	lsid:zoobank.org:pub:9F129B58-B240-4A85-A559-208014F12738
DOI	https://doi.org/10.5281/zenodo.12815722
persistent identifier	https://treatment.plazi.org/id/03F74B5E-FA26-FF83-FF29-F9C75D39E3BF
treatment provided by	Felipe
scientific name	Sclerodermus alternatusi Yang
status	sp. nov.

Treatment

Sclerodermus alternatusi Yang , sp. nov. ( Figs 2–24 View Figures 1–2. 1 View Figures 3–10 View Figures 11–15 View Figures 16–24. 16 )

Sclerodermus alternatusi Yang : Chen et al., 2019a: 114–119; Chen et al., 2019b: 848–854; Tang et al., 2022a: 1361–1366; Tang et al., 2022b: 83–88; Tang et al., 2023: 499–506. nom. dub.

Diagnosis. The new species is close to S. puparia e Yang & Yao, 2012, but can be distinguished from the latter by the following characters: alate female forewing dark infuscate and only paler medially, veins brown black, pterostigma short and punctiform, anal vein well developed (vs. forewing hyaline only slightly infuscate on apical 1/5, veins yellow brown, pterostigma absent, anal vein indistinct); apterous female with pronotal disc 1.0 times as long as width, sternum one with 2 lines of setae medially from base to apical and with 4 bristles close to hind margin ( Fig. 15 View Figures 11–15 ) (vs. pronotal disc 1.2 times as long as width, sternum one with more setae medially and without the 4 bristles close to hind margin); male with forewing infuscate and veins dark brown, length of pedicel + flagellum 1.8 times of head width (vs. forewing hyaline and veins yellow brown, length of pedicel + flagellum 1.5 times of head width).

Description. Holotype. Alate female ( Figs 3–10 View Figures 3–10 ). Full winged, LT 4.4 mm, LH 0.68 mm, WH 0.58 mm, WF 0.32 mm, LM 1.23 mm, LPD 0.56 mm, WPD 0.50 mm, LFW 2.33 mm, LMT 1.81 mm.

Body brownish black with weak black tint; antenna, mandible, labial and maxillary palps, trochanters, tibiae and tarsi fulvous, all coxae concolor with body; femora and tibiae dark brown; forewing slightly infuscate, hindwing subhyaline, wing veins yellowish brown; terga 2–6 with hind margin fulvous.

Head ( Figs 3–6 View Figures 3–10 ) 1.2 times of width; frons, vertex and gena evenly convex with very dense and delicate engraved reticulation, as well as sparse white short setae; ocelli forming equilateral triangle; OOL 2.0 times of WOT and 6.4 times of POL; POL as long as AOL, DAO 0.044 mm; frons width 1.38 times of eye height; eyes bare; distance between median ocellus and eye 1.14 times of eye height; face sunken at position about to lower margin of eyes as declivity and with a longitudinal shallow sulcus medially in declivity; antennal bases located at lower margin of declivity; distance between toruli 1/2 of their own width, and distance between torulus and eye 1.86 times of torulus width; malar space 0.6 times of torulus width and 0.33 times of mandible basal width; mandible with three teeth and third one smallest; clypeus triangular, modified as inversed “V” shape lamina located between toruli. Antenna ( Figs 5–6 View Figures 3–10 ) with short but dense suberected setae; scape curved slightly and clavated apically and with length nearly as long as eye height (26: 28), its apical width 0.38 times of length; length and width of scape, pedicel, and flagellum segments 1–11 as following proportions: 78(26), 24(15), 14(10), 13(12), 14(14), 16(16), 17(17), 14(17), 16(17), 16(17), 16(17), 17(17), 36(17).

Mesosoma ( Fig. 7 View Figures 3–10 ) with delicate and dense engraved reticulation appearing subpolished, scattered with sparse short brown setae. Setae denser and longer at lateral sides of pronotal flange. Scutellum having about 26 setae scattered laterally and posteriorly, and more obvious than those on pronotum and mesonotum (observed at dorso-laterally). Pronotum campanulate-shaped, distinctly and evenly convex, length of disc 0.8 times as long as its maximum width; posterior margin incurved medially; length of pronotal flange 0.27 times of pronotal disc length; pronotum (including pronotal flange) 0.90 times of mesoscutum and 0.47 times remainder of mesosoma.

Mesoscutum strongly convex and being highest at mesosoma, 0.58 times of maximum width and without notauli; scutellum tongue-shaped, relatively convex and flattened dorsally and 0.70 times of mesoscutum, and about 0.88 times of width; scutellar pits connected by a transverse furrow. Propodeum nearly rectangular, slightly and evenly convex dorsally, and nearly at same level with mesoscutum; its length (including propodeal declivity) as long as maximum width (between two anterior corners), and 1.32 times of mesonotum, 1.25 times of pronotum (with flange); propodeal disc at anterior third slightly constricted; anterior corners distinctly expanded outwards and thus width here 1.4 times of width along posterior margin; disc at anterior 1/6 with raised oblique striations laterally and other part of disc with delicate dense engraved reticulations; propodeal declivity descending at about 110° with disc without sharp angle. Mesopleuron bulged considerably with delicate fine reticulation and sparse setae. Forewing ( Fig. 8 View Figures 3–10 ) 3.4 times of width; outer margin with long fringe; subcosta, median and basal veins well developed and thus composing distinct basal cell; stub vein (Rs+M) conspicuous and extending down-outwards and touching anal vein which being well developed and thus forming clear submedian cell; prostigma stublike; pterostigma short, punctiform; radial vein absent. Hindwing ( Fig. 8 View Figures 3–10 ) simple.

Metasoma ( Figs 9–10 View Figures 3–10 ) with very short but distinct petiole, having several longitudinal carinae dorsally; gaster laceolate, about 2.4 times of width; its width 1.4 times of mesoscutum and 1.3 times of head; its length 1.6 times of mesosoma; terga nearly polished but with reticulation more superficial than those on mesosoma, and with sparse setae, tergum 4–7 with several long setae besides normal setae; posterior margin of tergum 1 with posterior margin half circular; terga 2–5 with transverse impression forming a pair of submedial posteriorly directed angles near posterior margin; tergum 6 with hind margin curved posteriorly; tergum 7 triangulate and prominent apically. Sternum 1 with hind margin curved posteriorly, sternum 2–4 with transverse impression having a pair of submedial posteriorly directed angles as on terga; sternum 1 at anterior 3/4 medially with relative dense setae and not arranged as two longitudinal rows besides setae decumbent along posterior 1/4, and its basal part with four erect bristles too; sternum 2–5 scattered short setae along posterior margin, as well as 4–16 erect bristles ( Fig. 15 View Figures 11–15 ).

Paratype. Apterous female ( Figs 11, 15 View Figures 11–15 ). Body castaneous with pronotal flange and posterior margin of pronotum yellowish brown; mesoscutum and tail part of metasoma testaceous; all segments of antennae testaceous; legs with coxae and femora concolor with body, all tibiae brown and tarsi testaceous; clypeus and mandible yellowish brown, teeth and lower part of mandible castaceous. Other characters similar to alate female; head and metasoma with more delicate superficial reticulation than those on mesosoma. LT 3.81mm, LH 0.71 mm, WH 0.59 mm, WF 0.31mm, LM 1.07mm, LMT 2.13 mm, LPD 0.54 mm, WPD 0.4 mm.

Head ( Figs 11–13 View Figures 11–15 ) in front view with length 1.20 times of width, and sides convergent downwards with upper side slightly wider than lower (1.26 times); frons evenly convex with distinctly delicate engraved reticulation and scattered sparse setae; ocelli absent; anterior margin of clypeus raised as inverted “V” shape; mandible with three teeth, basal tooth smallest and second smaller than front, front one largest. Torulus close each other; antenna filamentary; antennal ( Fig. 12 View Figures 11–15 ) flagellum with short and dense suberected setae; scape curved and gradually thicken toward apex, as well as planate ventrally, its dorsal side smooth with sparse setae; pedicel drum-like and politus; length and width of scape, pedicel and flagellum 1–11 as following proportions: 80(25), 22(16), 14(12), 11(13), 11(13), 12(14), 15(15), 16(15), 17(16), 16(15), 17(15), 16(14), 32(14). Flagellum 1 constricted basally; length of apical flagellum about 2.30 times of its maximum width. HE 0.20 mm, WF 1.67 times of HE; LH 1.18 times of WH. WH 3.1 times of HE.

Mesosoma. Pronotal disc ( Figs 11, 13 View Figures 11–15 ) 1.04 times of its width, posterior margin nearly straight, and length of pronotal flange 0.16 times of pronotal disc. Mesoscutum absent; scutellum well developed ( Fig. 13 View Figures 11–15 ) with shape tongue-like, its length 0.56 times of pronotum and 0.61 times of propodeum. Propodeum slightly constricted submedially, length 1.14 times of width in dorsal view, and basal width 0.90 times of posterior width; posterior corners bluntly angled. All mesosoma segments with dense delicate engrave reticulation.

Metasoma ( Figs 14–15 View Figures 11–15 ) in dorsal view lanceolate in shape, terga with reticulation superficial and more delicate than those on mesosoma; gaster terga with maximum width longer than mesosoma (2.0 times) and head (1.38 times); other characters as in alate female but bristles on tergum 4–7 longer than those on alate female; setae on sternum 1 denser and not arranged as two lines medially from basal to apical, and with four bristles close to posterior margin; setae and bristles on sterna 2–5 as in alate female ( Fig. 15 View Figures 11–15 ).

Alate male ( Figs 16–24 View Figures 16–24. 16 ). Full winged; LT 2.2 mm, fuscco-rufous to brown black; antennae, tibiae and tarsi lutescens, other segments of legs concolor with body; forewing infuscate but slightly paler than that of alate female; hindwing nearly hyaline.

Head ( Figs 16–18 View Figures 16–24. 16 ) in front view subround, length 1.06 times of width; mandible with four teeth. Antennal ( Figs 16– 18 View Figures 16–24. 16 ) flagellum long and filiform; scape curved dorso-ventrally with shape spoon-like and length 2.1 times of width, its dorsum and venter with superficial engraved delicate reticulation, as well as sparse short setae dorsally; pedicel oviform with length 1.8 times of width; flagellum 1–11 with relative length and width as follows: 19(14), 16(14), 20(16), 20(17), 20(16), 20(16), 20(15), 21(15), 22(14), 22(14), 40(13); last flagellum segment longest and blunt apically; each flagellum segment with short and dense setae; combined length of pedicel plus flagellum 1.8 times of head width. Eyes and ocelli distinctly bulged; OOL 1.1 times of WOT; POL 1.0 times of AOL. Frons 1.35 times as wide as eye height; distance between median ocellus and eye 0.7 times of eye height. Mesosoma 2.3 times as long as width. Forewing with veins same as alate female ( Fig. 22 View Figures 16–24. 16 ). Metasoma ( Figs 16–17, 23–24 View Figures 16–24. 16 ) 2.65 times as long as width, and 1.14 times of mesosoma; metasomal terga with size and form about same as alate female; petiole ventrally with dense raised reticulation; sternum 1 with about 14 setae lined as two lines medially ( Fig. 24 View Figures 16–24. 16 ); other sterna with dense setae.

Variation. Some apterous females and males varies in color: body yellow brown, some even black, some with head, mesosoma and tergum yellowish brown; some individuals with antennae and tarsi yellow.

Material examined. Holotype, alate female, China: Wildlife Park forest, suburbs of Kunming City, Yunnan Province, 3.IV.2010, collected in the gallery of Monochamus alternatus on a pine tree Pinus yunnanensis (Franch.) , leg. Yang Zhongqi, Wang Xiaoyi, Duan Zhaoyao, Zhang Yinan. Paratypes. 1 apterous female and 1 male, same data as holotype; 62 apterous females, 52 alate females and 14 males, 24.V.2012, others same as holotype; 11 apterous females, 11 alate females and 1 males, Jindian National Forest Park, 10.V.2013, collected in the gallery of Monochamus alternatus on pine tree Pinus yunnanensis (Franch.) , leg. Duan Zhaoyao, Chen Peng; 60 apterous females, 16 alate females and 8 males, Gongqing Forest Farm, 28.V.28, collected in the gallery of Monochamus alternatus on pine tree Pinus massoniana (Lamb.) , leg. Tang Yanlong, Gao Shangkun.

Distribution. China (the Yunnan-Guizhou Plateau, i.e. Yunnan and Guizhou Provinces, probably other provinces where the pine tree Pinus yunnanensis is naturally distributed).

Etymology. The specific name refers to the specific name of the host species Monochamus alternatus .

Biological observations. The new species is a gregarious ectoparasitoid that attacks larvae of Monochamus alternatus . From one host larva, 6–38 individuals of the parasitoid could be reared out depending on the host larval size. The species overwinter by apterous females in the cerambycid galleries or in pine bark crevices, which became active for parasitizing in early April in Yunnan Province. Once a female locates a junior larva, it chews a hole through the bark of the pine tree to reach the host. Females can also use their front legs to excavate a tunnel through the tightly packed host frass in order to reach their quarry. Upon access a host, the female first stings the cerambycid larva to paralyze it, then feeds on the host larval haemolymph to obtain nutrients for its egg developing. The pre-oviposition feeding period lasts about a week. In the meantime, the female’s metasoma gradually expands and prolongs along with the developing of eggs. During this period, evenly 3.75 and maximally 9.48 third instar host larvae could be killed ( Zhang et al., 2012). Finally, the female starts to oviposit on the last host larva. Depending on host size, the female lays 6–38 or even more eggs spaced evenly over the host body. Egg stage lasts two to three days. The larva period only need for approximately seven days to consume up the host larvae. The mature larvae then spin silk cocoons to pupate inside around the host mummy. Pupation stage lasts about 20 days, the new offspring adult wasps finally produced with female: male ratio averages 22: 1, and a brood typically containing only 1– 2 males. In fact, the parasitoid has been applied in biological control practice and showed high parasitic rate on M. alternatus in China ( Yang et al., 2013). The development threshold temperature for egg, larva and pupa of the new species are 6.99±2.12, 10.67±3.43 and 13.5±2.71℃, while the effective accumulated temperature are 49.28±5.08, 166.67±34.02 and 225±43.3℃, respectively ( Chen et al., 2019b). Now, the substitute host Thyestilla gebleri ( Coleoptera : Cerambycidae ) was used for mass rearing the parasitoid ( Chen et al., 2019b; Tang et al., 2022a, b, 2023) for biological control by us and it is showed successfully.

Funding The study is part of the Research Program “The Key Techniques for Control Pine Wood Nematod”. We thank “Fundamental Research Funds of Chinese Academy of Forestry (CAFYBB2021ZG001)” for supporting the present study. The research is also supported by the National Natural Science Foundation of China (32370494): Taxonomic study of braconids parasitizing important cerambycids and screening of excellent natural enemies.