Christelenka Rohacek, 2023

Rohacek, Jindrich, Hammel, Joerg U. & Baranov, Viktor, 2023, Christelenkidae, a new extinct family based on a new taxon from Eocene Baltic amber (Diptera: Acalyptratae), with X-ray synchrotron microtomography imaging of its structures, Arthropod Systematics & amp; Phylogeny 81, pp. 475-498 : 475

3.2. Christelenka Rohacek gen. nov.

Type species.

Christelenka multiplex sp. nov., designated here.

Diagnosis.

Same as above for Christelenkidae fam. nov.

Description.

Male. Small (body length ca 3 mm), largely dark brown, subshiny (Figs 1 - 4 ). - Head: (Figs 5 - 10 ) higher than long; occiput dorsally concave (Fig. 7 ). Frons (Figs 6 , 9 ) moderately broad, hardly narrowed anteriorly, devoid of setae or microsetae in front of ors. Orbital plate very poorly delimited. Frontal triangle absent; ocellar triangle small and slightly elevated; ocelli small (Fig. 9 ); ptilinal suture distinct but lunule absent. Face (praefrons) slightly concave, evenly sclerotized; gena distinct from postgena (Fig. 5 ). Cephalic macrosetae (Figs 8 - 10 ): pvt small, convergent (crossed); vti upright, reclinate, subparallel (slightly inclinate), long; vte shorter, strongly exclinate; oc divergent, more upright than proclinate, situated within ocellar triangle; only 1 ors, slightly exclinate and reclinate, in posterior half of frons; vi present, curved medially (Figs 8 , 9 ); subvibrissa and genal seta not developed. Postocular setulae in single long row; postgena with 1 distinct seta (Fig. 8 ); peristomal setulae sparse. Eye bare, convex, suboval (Figs 5 , 6 ). Palpus rather slender (Figs 11 , 12 ), with a few setulae (Fig. 8 ). Subcranial (oral) cavity relatively large (Figs 11 , 12 ). Mouthparts with clypeus short and projecting little from oral cavity (Fig. 11 ) and labellum fleshy (Figs 8 , 11 , 12 ). Antenna (Figs 5 , 6 , 8 , 9 , 15 ) decumbent and geniculate between pedicel and 1st flagellomere. Pedicel cap-like, without dorsal seam or incision, with dorsal and lateral margins also simple, not projecting; 1st flagellomere suboval, laterally compressed (Figs 8 , 9 ); arista dorsobasal, inserted extremely basally, very shortly pubescent (Figs 9 , 15 ). - Thorax: with mesonotum distinctly convex, somewhat hump-like anterodorsally (cf. Figs 1 , 3 , 13 , 14 , 17 ). Humeral (postpronotal) callus and notopleural area more (postpronotum) or less protruding. Mesopleuron (anepisternum) with slightly elevated ridge at posterior margin dorsally; dorsal membranous part of pleural suture separating it from pteropleuron (anepimeron) enlarged. Scutellum large, broad, distinctly convex dorsally (cf. Figs 13 , 17 ); subscutellum well developed (Fig. 15 , 17 ). Metasternal area bare. Thoracic chaetotaxy (Figs 15 , 16 ): 1 hu plus 6-8 microsetae on humeral callus; 2 npl; 1 prs; 1 sa; 1 pa; 1 postsutural dc, situated far behind level of sa; ac microsetae unordered, in about 6-8 incomplete rows; 2 sc, apical sc crossed, laterobasal sc longest and strongest of thoracic setae (Fig, 16); no ppl; no mesopleural (anepisternal) seta or setula; 1 (posterior) stpl; prosternum obviously bare. - Wing: (Figs 2 , 18 , 19 ) rather elongate, with apex somewhat pointed. C extended to apex of M but its last part (Cs4) attenuated; C in Cs2 and Cs3 with dense uniform setulae ending in middle of Cs3 (Fig. 18 ). Two costal breaks (smaller humeral, larger subcostal) developed. Sc distinct but distally fused with R1 but without preapical kink. Humeral crossvein not developed. R1 short, robust and bare. R2+3 long, subparallel with C, ending in C farther from wing apex than M. R4+5 distally subparallel with M, ending in C at wing apex. Distal part of M terminally weakened and reaching wing margin (Fig. 19 ) (in right wing, cf. Fig. 18 , M does not reach margin but considered anomalous). Discal (dm) cell elongate, distally widened; anterior crossvein (r-m) situated slightly beyond basal fourth of cell dm. Distal part of CuA1 reaching wing margin; A1 short, ending far from wing margin. Cells bm and cup closed. Anal lobe well developed. Alula (not clearly visible) small, narrow. Haltere (Figs 13 , 15 ) relatively large. - Legs: relatively slender and long, fore leg shortest; cx1 (Figs 3 , 13 , 15 ) distinctly elongate, with 1 seta in middle of ventral margin; f1 with 1 enlarged posterodorsal subapical seta and 1 dorsal seta in anterior three-fifths (Figs 20 , 21 ), with anteroventral ctenidium-like row of 8 small, very short blunt spines (Fig. 21 ); f2 (Fig. 22 ) with row of 8 anterior setae becoming longer towards apex; f3 with 2 strong setae (Fig. 23 ): longer anteroventral seta at distal third, and shorter dorsal seta at distal fourth. All tibiae (fore tibiae obscured) with 1 dorsal preapical seta; t2 (Fig. 22 ) with 1 ventroapical seta, shorter than dorsal preapical seta; t3 (Fig. 23 ) with dorsal preapical seta longer than on other tibiae. Claws on all tarsi well developed. - Abdomen: (Figs 24 - 28 ) slender, elongate. Preabdominal terga and sterna modified: T1 short (slightly shorter than T2), distinctly separated from T2; T2-T4 short (see also Fig. 17 ), transverse, subequal in length; T5 greatly elongated, somewhat enlarged, expanded lateroventrally (Figs 24 - 28 ). Preabdominal sterna S1-S4 short, total length subequal to total length of T1-T4 (cf. Figs 17 , 25 , 28 ); S1 (shortest), S2 (longer), S3 and S4 (longer and wider than S2); S5 very elongate (though shorter than T5) and narrow (Fig. 32 ). Pleural membrane of preabdominal segments reduced. - Postabdomen: (Figs 24 - 27 , 29 , 30 , 32-35 ) more or less symmetrical. T6 seemingly absent (cf. Figs 29 , 30 ) but forming short band-like sclerite hidden under enlarged T5 (cf. Figs 27 , 32 ). S6 (Figs 25 , 31-35 ) of moderate length, trapezoidal, symmetrical (Fig. 35 ). T7 absent. S7+S8 fused to form slightly asymmetrical dorsal saddle-shaped synsclerite bearing pair of robust dorsolateral setae. - Genitalia: Epandrium (Figs 25 , 27 , 29 , 30 ) arch-shaped, open ventrally; anal fissure large (cf. Figs 34 , 35 ). Cerci free, symmetrical, robust, situated below anal fissure (cf. Fig. 30 ). Gonostyli (Figs 27 , 30 , 32 ) simple, separate from epandrium but somewhat asymmetrical. Hypandrium relatively short, obviously frame-shaped (Figs 34 , 35 ). Postgonite symmetrical, simply pointed and elongate with apex exceeding that of aedeagus (Figs 27 , 30 , 32-35 ). Distiphallus (?) short, relatively broad, especially distally (see Fig. 35 ). - Female. Unknown.

Etymology.

The name of the genus is an abbreviated compound of the first names of two ladies, viz. Christe[l] + Lenka, playing important roles in the scientific career of the first author. It is dedicated to Christel Hoffeins (Hamburg, Germany) who discovered this amazing fly in Baltic amber, and to Lenka Roháčková, the wife of the first author, for her lifelong support and patience with his research in dipterology.

Figures

Figure 17. Christelenka multiplex sp. nov., male holotype, anterior part of body: sagittal section right laterally. Scale bar: 0.5 mm. For abbreviations see 2.2.4. Morphological terminology. Microtomograph image by V. Baranov.

Figures 1, 2. Christelenka multiplex sp. nov., male holotype. 1 specimen in the whole amber preparatum, left laterally, with blue background; 2 whole specimen dorsally, with blue background. Scale bars: 1.0 mm. Photos by J. Rohacek.

Figures 3, 4. Christelenka multiplex sp. nov., male holotype. 3 whole specimen, left laterally; 4 ditto, right laterally. Scale bars: 1.0 mm. Photos by J. Rohacek.

Figures 5 - 7. Christelenka multiplex sp. nov., male holotype. 5 head left laterally; 6 ditto, frontally; 7 ditto, laterocaudally. Scale bar: 0.5 mm. Photos by J. Rohacek.

Figs 8 - 10. Christelenka multiplex sp. nov., male holotype, cephalic chaetotaxy. 8 head left laterally; 9 ditto, frontally; 10 ditto, laterocaudally. - Scale bar: 0.5 mm. For abbreviations see 2.2.4. Morphological terminology.

Figures 11, 12. Christelenka multiplex sp. nov., male holotype. 11 head frontoventrally, with some structures coloured; 12 ditto, without colours. Scale bar: 0.5 mm. For abbreviations see 2.2.4. Morphological terminology. Microtomograph image by V. Baranov.

Figures 15, 16. Christelenka multiplex sp. nov., male holotype, thoracic chaetotaxy. 15 thorax, left laterally; 16 ditto, dorsally. Scale bar: 0.5 mm. For abbreviations see 2.2.4. Morphological terminology.

Figures 13, 14. Christelenka multiplex sp. nov., male holotype. 13 whole specimen, left laterally; 14 ditto, right laterally. Scale bar: 1.0 mm. Microtomograph images by V. Baranov.

Figures 18, 19. Christelenka multiplex sp. nov., male holotype, wings. 18 right wing, dorsally; 19 left wing, dorsally. Scale bar: 1.0 mm. For abbreviations see 2.2.4. Morphological terminology.

Figures 20 - 23. Christelenka multiplex sp. nov., male holotype, legs. 20 left fore femur, dorsally; 21 right fore femur, anteriorly; 22 right mid femur and tibia, anteriorly; 23 left hind femur, tibia and tarsus, anteriorly. Scale bar: 0.3 mm. For abbreviations see 2.2.4. Morphological terminology.

Figures 24, 25. Christelenka multiplex sp. nov., male holotype. 24 abdomen, left laterally; 25 ditto, with some structures coloured. Scale bar: 0.5 mm. For abbreviations see 2.2.4. Morphological terminology. Microtomograph image by V. Baranov.

Figures 28 - 30. Christelenka multiplex sp. nov., male holotype, abdominal structures. 28 abdomen, left laterally; 29 postabdomen with terminalia, right laterally; 30 ditto, left laterally. Scale bars: 28 - 0.5 mm; others - 0.2 mm. For abbreviations see 2.2.4. Morphological terminology.

Figures 31 - 35. Christelenka multiplex sp. nov., male holotype, abdominal structures. 31 abdomen (without 1 st segment), sagittal section right laterally, with some structures coloured; 32 posterior end of abdomen, right ventrolaterally, with structures coloured; 33 ditto, without colours; 34 posterior end of abdomen, ventrally; 35 ditto, enlarged and coloured. Scale bars: 0.2 mm. For abbreviations see 2.2.4. Morphological terminology. Microtomograph images by V. Baranov.

Figures 26, 27. Christelenka multiplex sp. nov., male holotype. 26 posterior half of abdomen, right laterally; 27 ditto, with some structures coloured. Scale bar: 0.2 mm. For abbreviations see 2.2.4. Morphological terminology. Microtomograph image by V. Baranov.