Cretevania kachinensis, ROSSE-GUILLEVIC & JOUAULT, 2023

ROSSE-GUILLEVIC, SIMON & JOUAULT, CORENTIN, 2023, A new species of Cretevania Rasnitsyn, 1975 (Hymenoptera: Evaniidae) from the mid-Cretaceous Kachin amber, Palaeoentomology 6 (3), pp. 242-249 : 243-245

Cretevania kachinensis sp. nov.

( Figs 1–3 ) urn:lsid:zoobank.org:act:3C7621BE-F2E1-4F5C-8A47-E53C3746

Material. Holotype IGR.BU-075 (in an amber piece measuring 11 × 6 × 1 mm, with a few stellate hairs and a Thysanoptera), deposited in the amber collection of the Geological Department and Museum of the University of Rennes, France ( IGR).

Etymology. The species name refers to the state of the type locality of the amber piece.

Diagnosis. Antennae with 10 flagellomeres; scape shorter than head length; pedicel very short, about as long as wide. Forewing with pterostigma elongate, longer than 2r-rs; pterostigma base basad of 2Rs middle; vein 1Rs about 0.25× as long as 1M and subvertical to R; 1+2r cell 1.4× as long as 3r cell; 2r-rs 2.25× as long as pterostigma width; 2Rs slightly longer than 3Rs; 1m-cu anteriad of 2Rs+M fork, angle between 1m-cu and 2Cu ca. 110°; 1mcu cell about 1.6× as long as wide; 2rm cell triangular, ca. 1.8× as long as 1mcu cell; 2r-m spectral (outlined by the absence of microtrichia); 1cu-a distinctly postfurcal; 2cua cell rectangular (1cu-a and 2cu-a complete, and A slightly overpassing 2cu-a); 2cu-a straight; 2m-cu absent; A not fused with 2cu-a.

Locality and horizon. Noije Bum Hill, Hukawng Valley, Kachin State, Myanmar; upper Albian to lower Cenomanian, mid-Cretaceous.

Description. Male. Body mostly black (complicating the observation of mesosomal structures). Total length ca. 3.2 mm.

Head ca. 0.38 mm long, 0.5 mm high (0.76× as long as high), covered with minute erected setae. Eyes kidneyshaped ca. 0.15 mm long, ca. 0.22 mm high (0.68× as long as high). Antennae with 12 antennomeres, ca. 1.12 mm long and ca. 0.05 mm wide; scape short and thick, shorter than head length; pedicel very short, about as long as wide; flagellomeres cylindrical, distinctly longer than wide, gradually and slightly thickening and shortening towards apex, except apical one (flagellomere I ca. 0.11 mm long, penultimate 0.07 mm long, and apical one 0.12 mm long); distal flagellomere acuminate. Clypeus short and lenticular, with a sigmoidal profile. Mandibles robust, bases apparently broader than clypeus length. Maxillary palpus with at least four palpomeres, length of measurable part 0.23 mm, apical palpomere acuminate. Labial palpus not visible.

Mesosoma 0.98 mm long, 0.5 mm high covered with minute erected setae; long, white and erected setae present ventrolaterally (on mesopleuron and propleuron). Mesopleuron with anepisternum and katepisternum delineated by a conspicuous carina. Propodeum and metapleuron areolate-rugose. Mid and hind legs close together, distinctly separated from forelegs (distance between fore and mid coxae 0.04 mm). Forelegs: coxa 0.24 mm long, 0.1 mm wide; trochanter 0.16 mm long, 0.08 mm wide; femur 0.38 mm long, 0.06 mm wide; tibia setulose 0.5 mm long, 0.03 mm wide; tarsus 0.48 mm, 0.03 mm wide, basitarsomere slightly shorter than remaining tarsomeres lengths combined, all others subequal in length. Mid-legs: coxa 0.37 mm long, 0.04 mm wide; trochanter 0.23 mm long, 0.04 mm wide; femur 0.53 mm long, 0.07 mm wide; tibia setulose 0.52 mm long, 0.04 mm wide; tarsus 0.51 mm long, 0.03 mm wide, basitarsomere about same length as tarsomeres II– IV, tarsomere V slightly longer than tarsomere IV. Hindlegs: coxa very robust (strongly enlarged) 0.39 mm long, 0.18 mm wide; trochanter 0.25 mm long, 0.09 mm wide; femur very robust (strongly enlarged) and setulose, 0.53 mm long, 0.18 mm wide; tibia widening after midlength, distinctly setulose along dorsal edge and punctate, 0.7 mm long, 0.1 mm wide; tarsus 0.75 mm long, 0.04 mm wide, basitarsomere slightly shorter than remaining tarsomeres lengths combined, all others subequal in length. Tibial spurs formula 1-2-2; tarsal claws simple; arolium present.

Forewing hyaline, covered with microsetae, 1.7 mm long and 0.67 mm wide; costal area at most as broad as pterostigma; pterostigma fully sclerotized, infuscate, darker basally; 1Rs extremely short, strongly angled with 1M; 1Rs+M longer than 2r-rs, 0.4× as long as 2Rs; 2Rs long and curved; 2r-rs reaching Rs slightly anteriad 2rm; 3Rs slightly curved reaching wing margin well before apex; R continuing along wing margin distad cell 3r apex; M+Cu basal half spectral; cell 1mcu trapezoidal, longer than wide, with sides 1Rs+M and 2Cu subparallel (both veins straight); M geniculate, angle between 2M and 3M ca. 160°; 2M curved; 3M slightly sigmoidal, longer than 2M; A straight; 1Cu slightly longer than 1Rs, slightly angled with 2Cu; 2Cu shorter than 1Rs+M; 3Cu long, distal third curved towards posterior wing margin; cell 2cua shorter and thinner than cell 1mcu; Rs, M and Cu distal abscissae reaching wing margin. Hind wing small (apex nearly aligned with 2Rs+M), hyaline, covered with microsetae; R with three(?) hamuli.

Metasoma 2.11 mm long, 0.55 mm wide; petiole swelled ventrally in distal third, 0.75× as long as rest of metasoma, 0.8× as long as mesosoma; second metasomal segment sub-triangular (in lateral view), 0.44× as long as petiole. Parameres exerted and lobe-shaped.

Remarks. Cretevania kachinensis sp. nov. differs from the two other species close to where it keys out because of wing venation characters. The new species differs notably from C. vesca in having 2rm cell ca. 1.8× as long as 1mcu cell, 1Rs 0.25× as long as 1M and subvertical to the latter, pterostigma base basad midpoint of 2Rs, 2r-rs 2.25× as long as pterostigma width, 1+2r cell 1.4× as long as 3r cell, 2Rs slightly longer than 3Rs, 1m-cu located basad 2Rs+M fork, angle between 1m-cu and 2Cu of ca. 110°, 1mcu cell about 1.6× as long as wide, 1cu-a postfurcal, 2cua cell closed (1cu-a and 2cu-a complete, and A slightly overpassing 2cu-a).

Cretevania kachinensis sp. nov. differs from C. alcalai because of the presence of the vein r-m (spectral, vs. absent? in C. alcalai ), the 2cu-a and A distinct with 2cu-a straight (vs. fused to form a broadly curved vein), and the vein 1Rs subvertical (strongly inclined towards wing base in C. alcalai ).

The new species differs from the two other species known from the mid-Cretaceous Burmese amber ( C. tenuis and C. bechlyi ) because of its unique combination of wing venation characters but also owing to its antennae and eye shape. Cretevania kachinensis sp. nov. differs from C. tenuis in having 2r-rs much shorter than its distance to pterostigma base (about as long as its distance to pterostigma base in C. tenuis ), i. e., in having a much longer pterostigma. C. tenuis also has bigger and rounder eyes, 2Rs+M longer, and a thinner and longer 3r cell.

It is worth noting that Cretevania kachinensis sp. nov. is also, with C. bechlyi , the only other member of the genus bearing 10 flagellomeres (i. e., 11 in other Cretevania species). However, the scape and pedicel relative sizes are clearly different between the two species (scape very long and pedicel very short in C. bechlyi , more homogenous in size in Cretevania kachinensis sp. nov.). C. bechlyi also has a 2cu-a subequal in length to 1m-cu (smaller than 1m-cu in Cretevania kachinensis sp. nov.), and a petiole 0.5× as long as mesosoma (0.8× as long as mesosoma in Cretevania kachinensis sp. nov.). C. bechlyi also has a distinctly spatulate wing shape, i. e., area under 3Cu wide and expanded (the wing is more slender in Cretevania kachinensis sp. nov., i. e., not expanded under 3Cu).

Figures

FIGURE 1. Cretevania kachinensis sp. nov., holotype IGR.BU-075. A, Habitus in left lateral view. B, Habitus in right lateral view. Scale bars = 500 µm (A) and 750 µm (B).

FIGURE 2. Cretevania kachinensis sp. nov., holotype IGR.BU-075. A, Head in right laterofrontal view (arrows pointing to the flagellomeres). B, Detailed lateral left view of mesosoma (arrows point to the limit between anepisternum and katepisternum). C, Detailed lateral left view of legs (arrows pointing respectively to mid and hind tibial spurs). D, Detailed lateral left view of metasoma (arrow pointing to swollen petiole). Scale bars = 250 µm (A, D), 100 µm (B), 500 µm (C).

FIGURE 3. Cretevania kachinensis sp. nov., holotype IGR.BU-075. A, Detailed view of left fore- and hind wings (arrows pointing to the position of the crossvein 2r-m). B, Interpretative line drawing of fore and hind wing venations with the names of veins labeled and names of the cells in red font. Scale bars = 250 µm.