Perilampus monocteni Yoo & Darling, 2024

Yoo, Jeong Jae & Darling, D. Christopher, 2024, Integrative taxonomic revision of the Nearctic Perilampus hyalinus species complex (Hymenoptera, Chalcidoidea, Perilampidae) resolves 100 years of confusion about the host associations of P. hyalinus Say, Journal of Hymenoptera Research 97, pp. 1301-1383 : 1301-1383

Perilampus monocteni Yoo & Darling sp. nov.

Figs 10 , 11

Type locality.

Canada, Ontario, Peterborough County, Aspley.

Type material.

Holotype. “ CANADA, Ontario, Aspley No. S 64-3469 - 01 , 22. III. 1965 Ex. Monoctenus juniperinus On e. w. cedar, Lot 65.418 ”. The Monoctenus associated with the holotype was later re-identified as M. fulvus (Kevin Barber, personnel communication). The holotype is point-mounted (Female ROME 201079 , CNC). ROM Online Collection .

Paratypes. Canada: 7 females, 2 males. Ontario: 7 females, 2 males. City of Ottawa., Bells Corners : (5 females: ROME 207334 - CNC; ROME 207332 - GLFC; ROME 207333 - GLFC; ROME 207331 - ROME; ROME 207335 - USNM. 2 males: ROME 207329 - CNC; ROME 207328 - ROME) . Haliburton Co., Haliburton : (1 female: ROME 207336 - CNC) . Peterborough Co., Apsley : (1 female: ROME 201078 - CNC ).

Additional material examined.

Canada: 1 female, 1 male. Ontario: 1 female, 1 male. City of Ottawa., Bells Corners: (1 male: ROME 207330 - CNC). Renfrew Co., Beachburg: (1 female: ROME 201101 - CNC) .

Etymology.

The specific epithet is a noun in the genitive case meaning “ of Monoctenus ”, in reference to the species’ host preference for Monoctenus sawflies and their parasitoids.

Description.

Female (Fig. 10 ). Length: 2.1–3.8 mm. Color: head iridescent greenish blue or violet; mesosoma and metasoma iridescent greenish blue or violet; clypeus ventral margin black (Fig. 10 I, J ); antenna with scape and pedicel weakly iridescent greenish blue or violet, flagellum brown or black, lighter ventrad and distad.

Head (Fig. 10 G – J ): in dorsal view transverse, width slightly greater than twice length, HW / HL 2.1–2.2. Frontal carina: in anterior view straight to weakly sinuate below midlevel of eye; in dorsal view gradually narrowed V shape around median ocellus, FC / MOD 1.5–1.6; distance from lateral ocellus short, FCLO / LOD 0.6–0.7. Scrobal cavity: in anterior view wide, SW / HW about 0.5. Ocelli (Fig. 10 G ): a line between anterior margin of lateral ocelli reaching anterior margin of median ocellus. POL / OOL 1.8–2.0. Ocellar ratios LOD: POL: OOL: LOL: 1, 2.9–3.4, 1.8–2.0, 1.0–1.2. Vertex: with strong to weak transverse striations, without large piliferous punctures. Parascrobal area: in lateral view gradually narrowed towards lower eye margin; width narrow, PSW / EL about 0.3; sculpture strongly to weakly striate, without large piliferous punctures. Gena: entirely or mostly striate along outer eye margin with narrow and short smooth area, striate behind. Malar space: MSL / EH about 0.2. Lower face (Fig. 10 H, I, J ): with setae sparse laterad torulus, and sparse below. Clypeus (Fig. 10 I, J ): CW / CH 1.4–1.5; ventral margin concave; with wide bare area without setae near dorsal margin, extended ventrad medially.

Mesosoma (Fig. 10 B – F, K, L ): Lateral panel of pronotum: about as wide as prepectus, LPP / PPT 0.8–0.9; without flange or with small rounded flange below level of mesothoracic spiracle in posterior oblique view (Fig. 10 D ). Mesofemoral depression: smooth (Fig. 10 L ), weakly imbricate, or rugulose. Mesoscutum: punctures angulate, with narrow or slightly wide and weakly coriarious interspaces (Fig. 10 B ); lateral lobe usually weakly punctate with coriarious or smooth interspaces along notaulus (Fig. 10 C ); parascutal carina broadly curved, acuminate (Fig. 10 E ). Mesoscutellum: apex with inner margins gradually diverging (Fig. 10 K ); punctures angulate, with narrow or slightly wide and weakly coriarious interspaces. Axilla: in lateral view imbricate dorsad, and rugose-areolate (Fig. 10 F ) or carinate ventrad. Axillula: smooth dorsad. Fore wing: stigma small, 2.0–2.5 × as wide as postmarginal vein.

Male (Fig. 11 ). Length: usually smaller, 2.7–2.9 mm. As in female, except: Color: mesonotum sometimes with weak cupreous iridescence. Frontal carina (Fig. 11 D ): distance from lateral ocellus shorter, FCLO / LOD 0.3–0.4. Scape (Fig. 11 G, H ): pits sparse, covering about 0.4 × scape length.

Diagnosis.

Perilampus monocteni can be distinguished by a clypeus with a wide and bare area without setae near the dorsal margin, which is extended ventrad medially (Figs 10 I, J , 11 E, F cf. Figs 4 I , 5 E ).

Distribution

(Fig. 25 B ). Eastern Canada (Ontario).

Host association.

Perilampus monocteni can develop as a primary parasitoid of cedar sawflies (Fig. 26 G ), or as a hyperparasitoid, a parasitoid of dipteran parasitoids of cedar sawflies (Fig. 26 H ). Hosts: Diprionidae ( Hymenoptera ). Monoctenus fulvus (Norton) , M. suffusus (Cresson). Tachinidae ( Diptera ). Tachinids from M. suffusus .

Variation.

A female and male reared from Monoctenus spp. have slight variations in the clypeal setae. One has two setae on the mostly bare area of the clypeus dorsad ( ROME 201101), and the other lacks a distinctive bare area on clypeus dorsad ( ROME 207330). The host records and absence of diagnostic characters specific to the other species suggest that these two specimens are P. monocteni .

Remarks.

The available specimens of P. monocteni are unsuitable for the sequencing method used in this study. Despite the lack of genetic data, the species hypothesis of P. monocteni is supported by the distinctive setal distribution pattern on the clypeus and a unique host association. Perilampus monocteni is a paraisitoid strictly associated with Diprionidae similar to P. neodiprioni . However, P. monocteni parasitizes cedar sawflies and their parasitoids, unlike P. neodiprioni which parasitizes pine sawflies and their parasitoids. Of the total six specimens associated with Monoctenus cocoons, three were primary parasitoids of cedar sawflies ( ROME 207330, 207332, and 207336) and three were hyperparasitoids that parasitized dipteran parasitoids of cedar sawflies. ( ROME 207328, 207333, and 207335). The known distribution is restricted to eastern Ontario but this may be due to the solitary larval feeding behaviour of Monoctenus spp. (Rose et al. 2010) — in comparison, many Neodiprion spp. are characterized by gregarious larval feeding behaviour ( Haack and Mattson 1993) and more conspicuous and more often collected. The combination of sparse pits on a male scape, the lack of a triangular flange on the lateral panel of pronotum, and the female mesoscutum without strong cupreous iridescence suggest that P. monocteni is clearly a member of the P. hyalinus complex clade 2 but its precise phylogenetic placement needs to be determined with genetic data. But if the parasitism associated with conifer-feeding sawflies was derived only once in the P. hyalinus species complex, P. monocteni is probably the sister species of P. neodiprioni , which is also a member of clade 2.

Figures

Figure 4. Perilampus hyalinus Female A habitus, lateral view B habitus dorsal view C lateral lobe of mesoscutum along notaulus D lateral panel of pronotum, posterior oblique view E axillula F axilla G head, dorsal view H head, anterior view I lower face J parascutal carina K mesoscutellum apex L, M mesofemoral depression. [A ROME 185913; B, K ROME 189058; C, M ROME 185947; D, F ROME 189056; E, G ROME 162229; H ROME 167636; I ROME 189060; L ROME 162246]. Scale bar: 1 mm (A).

Figure 5. Perilampus hyalinus Male A habitus, lateral view B lateral panel of pronotum and parascutal carina, posterior oblique view C head, anterior view D head, dorsal view E lower face F lateral lobe of mesoscutum along notaulus G, H scape. [A Neotype, ROME 204130; B – D, F, G ROME 182798; E ROME 167638; H ROME 189059]. Scale bars: 1 mm (A); 100 μm (G, H).

Figure 10. Perilampus monocteni Female A habitus, lateral view B habitus, dorsal view C lateral lobe of mesosucutm along notaulus D lateral panel of pronotum, posterior oblique view E parascutal carina F axilla G head, dorsal view H head, anterior view I, J c lypeus K mesoscutellum apex L mesofemoral depression. [A, B, D, K Paratype, ROME 201078; C Paratype, ROME 207336; E, J, L Holotype, ROME 201079; F Paratype, ROME 207331; G – I Paratype, ROME 207334]. Scale bar: 1 mm (A).

Figure 11. Perilampus monocteni Male A habitus, lateral view B lateral panel of pronotum, parascutal carina C head, anterior view D head, dorsal view E, F clypeus G, H scape. [A – C, E, G Paratype, ROME 207328 D, F, H Paratype, ROME 207329]. Scale bars: 1 mm (A); 100 μm (G, H).

Figure 25. Distribution of the Nearctic species of the Perilampus hyalinus species complex A P. hyalinus (green circles) and P. crassus (red squares) B P. neodiprioni (cyan circles) P. monocteni (red stars) C P. sirsiris D P. seneca E P. arcus F P. pilosus (yellow stars) P. ute (blue triangles) P. sonora (red circles).

Figure 26. Cocoons, pupa, and host remains associated with reared specimens of Perilampus. A – C, E Neodiprion lecontei cocoons A, B P. neodiprioni as primary parasitoid C, E P. neodiprioni as hyperparasitoid, parasitoid of Ichneumonidae D Neodiprion virginianus cocoon, P. neodiprioni as hyperparasitoid, parasitoid of Tachinidae [insert: tachinid puparium spiracles] F Lepidoptera pupa, P. seneca as hyperparasitoid, parasitoid of Tachinidae G, H Monoctenus suffusus cocoons G P. monocteni as primary parasitoid H P. monocteni as hyperparasitoid, parasitoid of Tachinidae [insert: tachinid puparium spiracles]. Abbreviations: eh, emergence hole; ex, Perilampus pupa exuvia; Ic, ichneumonid cocoon; Lp, lepidopteran pupa; M, Monoctenus remains; Mc, Monoctenus cocoon; N, Neodiprion remains; Nc, Neodiprion cocoon; Tp, tachinid puparium. [associated Perilampus: A, B ROME 207376 C ROME 207377 D ROME 198223 E ROME 162273 F ROME 202000 G ROME 207330 H ROME 207328]. Scale bars: 1 mm.