Arkaditilla, Okayasu, 2021

Okayasu, Juriya, 2021, A new velvet ant genus Arkaditilla (Hymenoptera, Mutillidae, Trogaspidiini) from the Oriental Region, with review of species, Journal of Hymenoptera Research 84, pp. 145-168 : 145

Arkaditilla gen. nov.

Figures 1-6 , 7-12 , 13-18 , 19-36 , 37-48 , 49-66 , 67-72 , 73-76

Mutilla (in part): Cameron 1902: 76, ♂; Zavattari 1914: 100, ♂.

Timulla (Trogaspidia) (in part): Mickel 1935: 263, 264, ♂; 1937: 449, ♂.

Krombeinidia (in part): Lelej 1996a: 11, ♂.

Petersenidia (in part): Lelej 1996b: 94, 95, ♂.

Diagnosis.

Male. Frons punctate; vertex roundly sloping posteriorly; postgenal bridge flattened; hypostomal carina simple, without denticle; clypeus dorsally elevated; prementum without tubercle. Mandible apically bidentate, ventrally excised into basal tooth (Figs 19-24 ); inner margin expanded, forming subbasal tooth (Figs 13-18 ); dorso-lateral carina sharp, not crooked. Scape ventrally with two longitudinal carinae, densely punctate or mostly smooth with sparse punctures apically between carinae (Figs 25 , 27 , 29 , 31 , 33 , 35 ); flagellum with yellow or reddish brown ventral markings; F1 longer than F2, depressed (Figs 28 , 30 , 32 , 34 , 36 ) except A. bagrada with F1 cylindrical (Fig. 26 ). Mesosoma black; notaulus present, reaching anterior 1/3 to 1/2 of mesoscutum; parascutal carina forming weakly elevated, rounded tubercle posteriorly; tegula posterior margin slightly protruding over transscutal articulation, not recurved; mesoscutellum evenly convex, puncto-reticulate; mesopleuron divided into dorsal and ventral convexities by transverse groove; propodeum gradually sloping posteriorly, without sublateral longitudinal carina; propodeal dorso-lateral margin without denticles. Pterostigma length subequal to distance between origin of RS on vein SC and proximal base of pterostigma. Protibial spur slender; mesocoxa evenly convex; metacoxa evenly convex with long sparse recumbent setae, without tubercle on inner margin. Metasoma black with segments 1-2 or 3 orange; S2 swollen anteriorly, without lateral felt line (Figs 2 , 4 , 6 , 8 , 10 , 12 ); T7 medially with slender longitudinal smooth convex line; S6-S8 without lateral carina; S7 entirely exposed, 0.75 × as long as S8; S8 mostly sclerotized with posterior membranous area evenly convex posteriorly; left and right basiparameres ventro-medial margins connected to form postero-medial tongue-like tubercle (Figs 38 , 40 , 42 , 46 , 48 ); parapenial lobe spatulate, not flexed; ventral portion of basiparamere strongly projecting posteriorly to connect volsella (Figs 49 , 52 , 55 , 58 , 61 , 64 ); paramere antero-ventrally serrate (Figs 49 , 52 , 55 , 58 , 61 , 64 ); digitus straight, dorsal margin lamellate (Figs 67-72 ); paracuspis absent, tuberculate or stick-like; penis valves symmetrical, with posterior hook (Figs 50 , 51 , 53 , 54 , 56 , 57 , 59 , 60 , 62 , 63 , 65 , 66 ). Female. Unknown.

Type species.

Arkaditilla leleji gen. et sp. nov., designated here.

Species included.

This genus includes the following six species: Arkaditilla bagrada (Cameron, 1902), comb. nov., ♂ (Indonesia, Malaysia); A. depressicornis (Mickel, 1935), comb. nov., ♂ (Malaysia); A. frim sp. nov., ♂ (Malaysia); A. gibba sp. nov., ♂ (Indonesia); A. leleji sp. nov., ♂ (Indonesia); A. nallinia (Zavattari, 1914), comb. nov., ♂ (Indonesia).

Distribution.

Widespread in Sundaland, the Oriental Region (Figs 73-76 ).

Etymology.

I am delighted to name this new genus in honor of Arkady Stepanovich Lelej, a fellow mutillidologist, pioneer of Old World mutillid systematics, and friend, to celebrate his 75th birthday and 50th anniversary of his career since the publication of Lelej (1971), with a common suffix for mutillid genera. Gender feminine.

Biology.

This genus is rare in collections; only twelve specimens of A. bagrada , nine specimens of A. depressicornis , and seven specimens of A. nallinia have been reported by previous authors ( Cameron 1902; Zavattari 1914; Mickel 1935, 1937; Lelej 1996b). In this study, however, a series of 28 specimens collected in Malaise traps placed in a lowland rain forest at Pasoh Forest Reserve was examined, suggesting greater abundance in forested habitats. See Maetô et al. (1999) for sampling sites.

Remarks.

This new genus belongs to the former Petersenidiini Lelej, 1996 by having the penis valves symmetrical, and the species of this genus were formerly placed in Krombeinidia Lelej, 1996 ( Lelej 1996a) or Petersenidia Lelej, 1992 ( Lelej 1996b). However, the males of Arkaditilla differ from those of Krombeinidia and Petersenidia by having the mandible with a subbasal inner tooth (mandibular inner margin entire in Krombeinidia and Petersenidia ), the basiparamere antero-ventrally serrate (entire in Krombeinidia and Petersenidia ), and the digitus dorsal margin lamellate (digitus cylindrical in Krombeinidia and Petersenidia ). Within Trogaspidiini , the males of this new genus and Serendibiella Lelej, 2005 share the mandible with subbasal inner tooth, but the former differs from the latter by having the hypostomal carina without a tubercle (present in Serendibiella ), the mesocoxa evenly convex (laterally swollen in Serendibiella ), S2 without a lateral felt line (present in Serendibiella ), S8 flattened (with sublateral longitudinal carina in Serendibiella ), and the penis valves symmetrical (right penis valve longer than left in Serendibiella ).

Figures

Figures 1 - 6. Arkaditilla spp., ♂, habitus 1, 3, 5 dorsal view 2, 4, 6 lateral view 1, 2 A. bagrada (Cameron) 3, 4 A. depressicornis (Mickel) 5, 6 A. frim sp. nov., holotype. Scale bars: 3 mm.

Figures 7 - 12. Arkaditilla spp., ♂, habitus 7, 9, 11 dorsal view 8, 10, 12 lateral view 7, 8 A. gibba sp. nov., holotype 9, 10 A. leleji sp. nov., holotype 11, 12 A. nallinia (Zavattari). Scale bars: 3 mm.

Figures 13 - 18. Arkaditilla spp., ♂, face 13 A. bagrada (Cameron) 14 A. depressicornis (Mickel) 15 A. frim sp. nov., holotype 16 A. gibba sp. nov., paratype 17 A. leleji sp. nov., holotype 18 A. nallinia (Zavattari).

Figures 19 - 36. Arkaditilla spp., ♂ 19 - 24 mandible, lateral view 25, 27, 29, 31, 33, 35 scape, ventral view 26, 28, 30, 32, 34, 36 pedicel, F 1, and F 2, lateral view 19, 25, 26 A. bagrada (Cameron) 20, 27, 28 A. depressicornis (Mickel) 21, 29, 30 A. frim sp. nov., holotype 22, 31, 32 A. gibba sp. nov., holotype 23, 33, 34 A. leleji sp. nov., holotype 24, 35, 36 A. nallinia (Zavattari).

Figures 37 - 48. Arkaditilla spp., ♂, genitalia 37, 39, 41, 43, 45, 47 dorsal view 38, 40, 42, 44, 46, 48 ventral view 37, 38 A. bagrada (Cameron) 39, 40 A. depressicornis (Mickel) 41, 42 A. frim sp. nov., holotype 43, 44 A. gibba sp. nov., holotype 45, 46 A. leleji sp. nov., holotype 47, 48 A. nallinia (Zavattari).

Figures 49 - 66. Arkaditilla spp., ♂, genitalia 49, 52, 55, 58, 61, 64 genital capsule and volsella, inner view 50, 53, 56, 59, 62, 65 left penis valve 51, 54, 57, 60, 63, 66 right penis valve 49 - 51 A. bagrada (Cameron) 52 - 54 A. depressicornis (Mickel) 55 - 57 A. frim sp. nov., holotype 58 - 60 A. gibba sp. nov., holotype 61 - 63 A. leleji sp. nov., holotype 64 - 66 A. nallinia (Zavattari).

Figures 67 - 72. Arkaditilla spp., ♂, genital volsella, ventro-inner view 67 A. bagrada (Cameron) 68 A. depressicornis (Mickel) 69 A. frim sp. nov., holotype 70 A. gibba sp. nov., holotype 71 A. leleji sp. nov., holotype 72 A. nallinia (Zavattari). White arrows indicate the paracuspis.

Figure 73 - 76. Distributional map of Arkaditilla spp. based on specimens examined herein and the literature (Cameron 1902; Lelej 1996 b; Mickel 1935, 1937; Zavattari 1914) 73 A. bagrada (Cameron) (red circle) 74 A. depressicornis (Mickel) (blue circle) 75 A. frim sp. nov. (yellow circle), A. gibba sp. nov. (purple triangle), and A. leleji sp. nov. (light blue square) 76 A. nallinia (Zavattari) (orange circle).