Cleruchus breviclava Triapitsyn & Coray, 2022

Triapitsyn, Serguei V., Coray, Armin & Rugman-Jones, Paul F., 2022, A new species of Cleruchus (Hymenoptera, Mymaridae), an egg parasitoid of the invasive Cis chinensis (Coleoptera, Ciidae) in Switzerland, with new records of other congeners in Europe, Alpine Entomology 6, pp. 97-109 : 97

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Cleruchus breviclava Triapitsyn & Coray

sp. nov.

Cleruchus breviclava Triapitsyn & Coray sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5

Cleruchus sp.: Coray et al. 2022: 89-90 (host association, list of specimens reared in Basel, descriptive notes, illustrations).

Type material.

Holotype female (macropterous individual), deposited in NHMB, on slide labeled: 1. "SWITZERLAND: Basel-Stadt Basel, Universitäre Psychiatrische Kliniken 47°34'16.75"N, 7°33'50.15"E, 266 m, P. Vlček. Associated with Cis chinensis Lawrence in Antrodia xantha fungus on Pinus strobus block, subsequent series 9.vii.2021, A. Coray"; 2. "Mounted by V. V. Berezovskiy 2021 in Canada balsam"; 3. [magenta] " Cleruchus breviclava Triapitsyn & Coray HOLOTYPE ♀"; 4. "Det. by S. V. Triapitsyn 2021"; 5. [barcode database label/unique identifier] " UCRC [bold] UCRC_ENT 00541415". The holotype (Figs 1 View Figure 1 , 2a-c View Figure 2 ) has a pair of wings detached and mounted under the same coverslip.

Paratypes. 7 females and 3 males on slides [including 2 females (1 macropterous and 1 strongly brachypterous) and 2 males (1 macropterous and 1 strongly brachypterous), UCRC (molecular vouchers PR21-581-584, UCRC_ENT 00541371-00541374)], same data as holotype. All other specimens listed in Coray et al. (2022) from the type locality (as Cleruchus sp.) and deposited in NHMB are also included in the paratype series.

Additional specimens from Germany and Switzerland (other than from the same rearing at the type locality in Basel), listed by Coray et al. (2022), are not included in the type series; these are mostly stored in ethanol in NHMB.


Morphologically, fully winged female individuals of C. breviclava are most similar to those of the Palaearctic species C. detritus Bakkendorf, the type series of which was collected from soil in Chancy, Geneva, Switzerland ( Bakkendorf 1964). Its lectotype female (Fig. 6 View Figure 6 ) was designated by Triapitsyn et al. (2013) from one of the two macropterous original syntypes. In macropterous C. breviclava , the female antennal clava (Fig. 2a View Figure 2 ) is consistently relatively shorter than that in fully winged C. detritus (Fig. 6 View Figure 6 ), in which it is approximately the same length as combined length of F3-F6 according to the redescription in Triapitsyn (2014), being slightly shorter than the combined length of F4-F6 (but about as long as F4-F6 in the smaller, brachypterous female of C. breviclava ). The body of C. breviclava is notably longer (0.6-0.76 mm in macropterous, slide-mounted females) than that of macropterous females of C. detritus (0.45 mm according to Bakkendorf 1964), and the gaster is markedly longer (compare Figs 1a View Figure 1 , 2c View Figure 2 and Fig. 6b View Figure 6 , respectively), which is common in fungus dwelling species of the genus. Combined with notably shorter setae on the fore wing venation in C. breviclava (Fig. 1b View Figure 1 ), and a different habitat (fungus versus soil for C. detritus ), this strongly supports that these two species are clearly distinct despite having some morphological similarities in proportions of female funicular segments and fore wing chaetotaxy.

A key to both sexes of the European species of Cleruchus , which is based on that of the Palaearctic species in Triapitsyn (2014), is provided below to further facilitate their recognition.


Female (holotype). Body (Fig. 1a View Figure 1 ) brown to dark brown (gaster a little lighter, often basally only); scape and pedicel light brown, flagellum brown; legs mostly light brown. Head (Fig. 2b View Figure 2 ) a little wider than long in dorsal view, and about as wide as mesosoma. Vertex smooth; ocelli present but somewhat reduced, oval. Face subquadrate, small, faintly sculptured, with one seta near inner lower side of each torulus; torulus large, subtriangular, slightly below lower level of eyes, touching preorbital trabecula. Mandible bidentate. Antenna (Fig. 2a View Figure 2 ) with scape smooth, 4.5 × as long as wide (including small radicle); pedicel smooth, 1.7 × as long as wide, much longer than F1; F1 about as long as wide, much shorter than following funiculars; F2-F5 longer than wide, F2 shorter than following funiculars, F4 and F5 the longest and F6 the widest funiculars; F4-F6 each with 1 mps; clava a little shorter than F4-F6 combined, entire, 2.6 × on one antenna and 2.7 × on the other antenna as long as wide, with 6 mps. Mesosoma (Fig. 2b View Figure 2 ) mostly smooth except axilla with a faint sculpture. Mesoscutum wider than long, its midlobe with a pair of adnotaular setae. Axilla with 1 weak seta. Scutellum a little shorter than mesoscutum. Metanotum narrow, strap-like and hardly noticeable, with 2 very weak setae. Propodeum long, longer than mesoscutum or scutellum. Mesophragma broadly U-shaped, almost extending to posterior margin of propodeum. Macropterous (Fig. 1a-c View Figure 1 ). Fore wing (Fig. 1b View Figure 1 ) 10.4 × as long as wide, with venation typical of the genus; both macrochaetae very short; blade infuscate throughout, with 2 rows of microtrichia along anterior margin and 1 almost complete row of microtrichia along posterior margin; longest marginal seta 4.4 × greatest width of wing. Hind wing (Fig. 1c View Figure 1 ) 21 × as long as wide; blade slightly infuscate, with one incomplete row of microtrichia closer to anterior margin; longest marginal seta 6.2 × greatest width of wing. Petiole (Fig. 2b, c View Figure 2 ) short but clearly visible in slide-mounted specimens, 2.0 × as wide as long. Gaster (Fig. 2c View Figure 2 ) elongate, twice as long as mesosoma in the slide-mounted specimen; ovipositor 1.25 × length of metatibia and about 0.4 × 1ength of gaster, exserted beyond its apex.

Measurements (µm) of the holotype (as length or length: width). Body: 665; mesosoma 185; petiole 19; gaster 370; ovipositor 152. Antenna: scape (including radicle) 97; pedicel 36; F1 12; F2 18; F3 23; F4 27; F5 27; F6 25; clava 82. Fore wing 376: 36; longest marginal seta 157. Hind wing 378: 18; longest marginal seta 112.

Variation. Macropterous paratypes: body length of slide-mounted specimens 600-760 µm; mps usually on F4-F6 (1 on each) but sometimes F3 with 1 mps (Fig. 2d View Figure 2 ) on one or both antennae, clava 2.6-2.8 × as long as wide; fore wing 8.6-9.5 × as long as wide; ovipositor 1.2-1.3 × length of metatibia. Strongly brachypterous paratype (Fig. 3a, b View Figure 3 ): body length of slide-mounted specimen (Fig. 3b View Figure 3 ) 515 µm; ocelli present but relatively more reduced than in macropterous individuals; antenna (Fig. 3c View Figure 3 ) relatively shorter than in macropterous individuals, particularly F2-F4, mps only on F5 and F6 (1 on each), clava as long as F4-F6 combined; fore wing reduced to small, very short stub with a few short setae; hind wing apparently absent; ovipositor length 120 µm, 1.3 × length of metatibia.

Male. Macropterous paratypes (Fig. 4c View Figure 4 ): body length of slide-mounted specimens 585-590 µm. Ocelli (Fig. 5c View Figure 5 ) as in macropterous females. Antenna (Fig. 5a View Figure 5 ) with flagellum 10-segmented; scape (including radicle) 5.3 × as long as wide; F1 shorter than following flagellomeres and without mps; F2-F10 each with at least 1 mps, F10 the longest flagellomere. Fore wing (Fig. 5b View Figure 5 ) 9.8-10.4 × as long as wide. Gaster 1.3-1.4 × as long as mesosoma; genitalia (Fig. 5d View Figure 5 ) length 106 µm. Strongly brachypterous paratype (Figs 3d View Figure 3 , 4b View Figure 4 ): body length of slide-mounted specimen 470 µm. Ocelli apparently absent. Antenna (Fig. 4a View Figure 4 ) notably shorter than in macropterous individuals (some flagellomeres relatively shorter), with flagellum 9-segmented (F3 and F4 completely fused on one antenna but only partially fused on the other), scape (including radicle) 4.2 × as long as wide, F1 and F2 without mps. Genitalia length 94 µm.


The new species name is a noun in apposition referring to a relatively short antennal clava, compared to that in otherwise more or less similar congeners such as C. detritus .


Palaearctic region: Switzerland, and Germany ( Coray et al. 2022 [as Cleruchus sp.]).


Coleoptera , Ciidae : Cis chinensis Lawrence, 1991 in Antrodia xantha fungus ( Polyporales , Fomitopsidaceae ) on a block of Pinus strobus ( Pinaceae ).

Molecular analysis.

Four specimens of C. breviclava were extracted but only three yielded amplifiable DNA: PR21-581, PR21-582, and PR21-584. The DNA sequences of the COI (502 bp) and 28S-D2 (519 bp) regions were identical across all three specimens (GenBank accessions: OP758808-OP758810 and OP755253-OP755255, respectively). The ITS2 region (432 bp) of the two male specimens was also sequenced and found to differ at only a single nucleotide position (A-T at position 222; OP755251-OP755252). Taken together, the almost identical nature of these three loci provided unambiguous evidence that at least the three individual wasps of C. breviclava from which we were able to amplify and sequence DNA (one macropterous female, one macropterous male, and one strongly brachypterous male) are clearly conspecific. Although the DNA extraction from the fourth specimen (a strongly brachypterous female) appears to have failed, we believe it represents the same species. That is corroborated by the fact that all the wasps emerged from the same fungus.














Cleruchus breviclava Triapitsyn & Coray

Triapitsyn, Serguei V., Coray, Armin & Rugman-Jones, Paul F. 2022


Triapitsyn & Coray & Rugman-Jones 2022