Protanthomyza grimaldii, Roháček, 2020

Rohacek, Jindrich, 2020, Protanthomyza grimaldii sp. nov., a further member of the extinct subfamily Protanthomyzinae (Diptera, Anthomyzidae) from Baltic amber, ZooKeys 973, pp. 1-15 : 1

Protanthomyza grimaldii sp. nov. Figures 1-2 , 3 , 4 , 5-9 , 10, 11 , 12-14

Protanthomyza sp. nov.: Roháček 2013a: 451-452, fig. 7E, F (diagnosis, female only).

Etymology.

The species is dedicated to Prof. Dr. David Grimaldi (New York, U. S. A.), the distinguished American dipterist and palaeontologist, in recognition of his valuable contribution to the knowledge of amber fossil flies, including acalyptrates (largely from Dominican amber).

Type material.

Holotype ♂ labelled "Faszination Bernstein, Christel Hoffeins, Hans Werner Hoffeins" (framed on obverse), "1040-5a Diptera : Acalyptratae , Anthomyzidae ♂" (handwritten by C. Hoffeins, on reverse), "Baltic amber, Russia: Kaliningrad region, Yantarny", "obtained in May 2010 from Dr. Andrey Krylov, Kaliningrad, Russia", and "Holotypus ♂, Protanthomyza grimaldii sp.n., J. Roháček det. 2020" (red label) [amber piece embedded in polyester resin, size 8.6 × 7.9 × 4.8 mm], deposited in SDEI (inventory number Dip-00821). The original amber stone (in form of an icicle = Zapfenschlaube in German), size about 45 × 20 × 11 mm, with multiple layers and aggregation of inclusions, was cut in two pieces; that with the inclusion of P. grimaldii (No. 1040-5a) was separated, manually prepared and embedded in polyester resin by H. W. Hoffeins in August 2015. Syninclusions in 1040-5a: 1 stellate hair, pollen grains. Syninclusions in the remaining part (1040-5b, deposited in CCHH): Diptera : Empididae : 1 Rhamphomyia sp. female; 2 Mycetophilidae males + fragment; 1 Simuliidae ; 2 Chironomidae female and male; Trichoptera , not identifiable; Coleoptera fragment; Araneae fragment; stellate hairs. Paratype ♀ labelled "47b-1, (Baltic A.), 15.1 × 10.7 × 3.3 [mm]" (handwritten), " Protanthomyza sp.n. ♀, J. Roháček det. 2011" (yellow label) and "Paratypus ♀, Protanthomyza grimaldii sp.n., J. Roháček det. 2020" (yellow label) [shape of stone irregularly pentagonal, thin], temporarily held in CMTB; it will be deposited in AMNH. Syninclusions: only stellate hairs.

Type locality and age.

Russia: Kaliningrad region, Yantarny mine. Middle to Late Eocene, 48-34 Ma (cf. Seyfullah et al. 2018).

Diagnosis.

Ocellar triangle delimited by a groove; frontal triangle not delimited; 1st antennal flagellomere normal, not enlarged; arista bare; 3 or 4 dc macrosetae; f1 without a ctenidial spine; male epandrium elongate and posteriorly tapered, with a robust, hook-like, curved anteroventral process; female T7 short; female S6 and S7 broadly transverse.

Description.

Male (Figs 1 , 2 ). Total body length ca 2.6 mm; general colour brown to blackish brown; only head and some extremities partly ochreous to yellow.

Head (Figs 3 - 5 ) higher than long, anteriorly somewhat angularly protruding in front of eye margin (Fig. 5 ). Occiput very slightly concave, blackish brown. Frons relatively narrow, blackish brown only posteriorly around ocellar triangle, pale brown in anterior half to ochreous yellow at anterior marginal area surrounding frontal lunule. Frontal triangle not developed; ocellar triangle blackish brown, distinctly protruding and delimited by marginal groove. Ocelli large (Figs 3 , 4 ). Orbital plate lighter (ochreous yellow) anteriorly, becoming pale brown posteriorly where contrasting with blackish-brown vicinity of ocellar triangle. Frontal lunule long, ochreous yellow. Face relatively narrow, ochreous, medially lighter and somewhat depressed; parafacialia and anterior half of gena dirty yellow and narrowly brown bordered (gena ventrally); posterior half of gena and postgena brown; mouthparts yellow to ochreous, clypeus pale brown, palpus dirty yellow. Cephalic chaetotaxy (Figs 4 , 5 ): pvt (only left one visible) relatively short, convergent but not crossed; vti longest of cephalic setae, slightly inclinate; vte strongly exclinate and only slightly shorter than vti; 3 distinct ors, all slightly reclinate, posterior ors longest (about as long as vte), others becoming slightly shorter anteriorly; oc relatively thin (not longer than middle ors), proclinate (and unnaturally crossed in holotype), arising inside ocellar triangle; anterior half of frons with about 5 or 6 pairs of microsetae, mostly medially in front of ocellar triangle but a few (1 or 2) also between anterior and middle ors; vi distinct (Fig. 5 ), about 3 times as long as foremost peristomal setula; no subvibrissa; 4 or 5 weak proclinate peristomals; postocular setulae in two rows as usual but with only 3 setulae in inner row (Fig. 4 ); outer row of postoculars long, reaching ventral eye margin; postgena with 2 setae, anterior short, posterior longer. Palpus slender, elongate, with a few (3 visible) minute setulae distally (Fig. 5 ). Mouthparts relatively short. Eye bare, relatively large and strongly convex, suboval, anteriorly regularly rounded, with only posterior margin somewhat straighter; its longest diameter almost vertical and 1.16 times as long as shortest diameter. Gena low, its shortest height about 0.08 times as long as shortest eye diameter. Antenna medium-sized, generally porrect (Fig. 5 ) but directed anteroventrally to ventrally, with dark-brown basal segments and pale-brown to ochreous 1st flagellomere. Pedicel with 1 longer seta and several microsetae; 1st flagellomere oval, laterally compressed, with very short, dense and dark pilosity; arista about 1.8 times as long as antenna, entirely bare (Fig. 5 ), 2 basal segments slightly widened.

Thorax hardly narrower than head, brown to blackish brown, with shining mesonotum and duller pleural part. Mesonotum relatively convex, separated from scutellum by deep suture. Scutellum rounded subtriangular, wider than long, convex dorsally; postscutellum not visible. Thoracic chaetotaxy (see Figs 3 , 4 , 7 ) rich as usual in the genus: 1 short hu (markedly shorter than anterior npl) and only 2 or 3 setulae on humeral callus (= postpronotal lobe); 2 long npl, anterior slightly longer; 1 distinct prs (about as long as posterior npl); 1 long sa; 2 pa, external very long (longer than sa), internal shorter (not visible on left side in Fig. 4 ); 3 or 4 postsutural dc (number different on left and right sides) becoming shorter anteriorly, the hindmost longest (together with apical sc longest thoracic setae); ac microsetae dense, in 9 or 10 rows on suture, those in medial rows reaching up to posterior dc; prescutellar ac macrosetae long and strong, as long as sa; 2 sc, laterobasal shorter (about as long as prs), apical very long; no additional setulae on scutellum; 2 upcurved ppl, anterior distinct (as long as hu), posterior small. Mesopleuron (anepisternum) and sternopleuron (katepisternum) setose (Figs 4 , 7 ) as in most other species of Protanthomyza : 3 long mspl (1 dorsal upcurved and shortest, 1 posterodorsal and 1 posterior longest, cf. Fig. 7 ) and numerous setulae in posterodorsal half of mesopleuron; 1 long posterior stpl and about 9 or 10 setulae in posterior half of sternopleuron; other sclerites of pleural part of thorax bare.

Legs brown to ochreous, femora darkest, fore coxa pale ochreous. f1 lacking ctenidial spine; 5 (2 longer) distinct widely-spaced setae in posterodorsal row; setae in posteroventral row more numerous but short and weak. f2 with 2 or 3 anterior setae near middle (cf. Fig. 14 ), otherwise shortly setulose as is f3. t2 with distinct ventroapical seta (about as long as maximum width of t2) and 2 or 3 small setae adjacent to the latter; t1, t3 and all tarsi simply setulose but basitarsi of all legs with ventrobasal setulae somewhat longer than others.

Wing (Figs 1 , 6 ) moderately long and narrow, widest at distal third; veins brown to pale brown, membrane unicolourous, pale-brown tinged; C with more or less distinct subcostal break and somewhat attenuated at humeral cross-vein. C extended to apex of M, densely uniformly setulose on Cs2 (from subcostal break to apex of R2+3), finely short-pilose more distally (on Cs3 and Cs4); Sc distinct, separate almost along its entire length, only apically fused with R1 to form preapical kink (see Fig. 6 , pk); R1 short, dilated distally due to fusion with Sc; R2+3 long, very slightly sinuate to almost straight and only its extreme apex slightly upcurved to C; R4+5 slightly recurved in distal half, divergent from R2+3 and apically slightly convergent with M; M almost straight. Cell dm of moderate length, narrow proximally and much widened distally, with angle of anterior outer corner obtuse while that of posterior outer corner distinctly acute (cf. Fig. 12 ); r-m situated in basal third of cell dm; dm-cu straight; apical portion of CuA1 much shorter than distance between r-m and dm-cu, distinctly longer than dm-cu and almost reaching wing margin; A1 relatively long but ending far from wing margin; A2 well developed, slightly shorter than A1 (Fig. 6 ); alula distinct but narrow (Fig. 6 ). Wing measurements: length ca 2.4 mm, width ca 0.8 mm, Cs3: Cs4 = 1.38, r-m\dm-cu: dm-cu = 3.50, r-m\dm-cu: CuA1 = 2.50. Haltere (Figs 4 , 8 ) pale ochreous, knob relatively large, darker dorsally.

Abdomen (Figs 1 , 2 , 8 ) relatively short, robust but not very broad. Preabdominal terga blackish brown; T1 fused with T2 but delimited by a groove (Fig. 8 ); T1 finely short-setose, T2-T5 with relatively long and dense setae (Fig. 8 ); T2 somewhat shorter than T3, T3-T5 subequal in length, all relatively short and transverse (Figs 2 , 8 ). Preabdominal sterna mostly invisible (Figs 2 , 8 ) but probably small (narrow) and pale-pigmented; only S5 discernible (Fig. 8 ), paler brown and shorter than adjacent T5, with sparse setae. Also 2 setae of S4 visible on right side of abdomen (Fig. 8 ) but margins of sclerite are not recognizable. Postabdomen: S6 and S7 not visible because situated on obscured left side of abdomen (cf. Fig. 1 ), probably asymmetrical and (partly) fused together (dorsally also with S8) as in other Protanthomyza species (cf. Roháček 2013a, fig. 4H). S8 relatively long, blackish brown, situated dorsally and readily visible on right side (Figs 2 , 8 ), almost bare, with only a few setulae.

Genitalia. Epandrium (Figs 8 , 9 ) relatively long but tapered posteriorly, with anteroventral corner modified to distinct, flat and somewhat hook-like projection (see Fig. 9 , avp) distinctly different from those in other Protanthomyza species where known (cf. Roháček 2013a, figs 1F, 2E, 4H, 6B, 12C). Epandrium anterodorsally with 3 pairs of long erect setae (the most lateral markedly shorter), otherwise with scattered short setae. Anal fissure relatively small and cercus reduced (small and narrow) with fine short pubescence (Fig. 9 ). Gonostylus not discernible (on any side) but probably small and pale. No structures of internal genitalia visible.

Female (Figs 10 , 11 ). Similar to male unless mentioned otherwise. Total body length ca 2.9 mm. pvt short, strongly convergent, with apices meeting medially; oc proclinate and divergent; setae in posteroventral corner of postgena subequal. Palpus with more setulae (5 or 6) visible ventrally, subapically and apically. Mesonotum with 3 strong dc in left row and with 4 dc (2 posterior strong, 2 anterior short and weaker) in right row; prescutellar ac macrosetae longer than sa; about 8 rows of ac microsetae on suture. Legs more slender but with same chaetotaxy as in male, except t2 (Fig. 14 ) with ventroapical seta longer. Wing (Fig. 12 ) venation resembling that of male but cell dm shorter and cross-vein r-m situated more distally. Wing measurements: length 2.58 mm, width 0.95 mm, Cs3: Cs4 = 1.44, rm\dm-cu: dm-cu = 2.37, rm\dm-cu: CuA1 = 1.97.

Abdomen (Figs 11 , 13 ) only partly visible. Preabdomen with terga (T1+2, T3-T5) obviously darker brown than sterna, relatively narrow, hence pleural part of preabdominal segments large; setae on T3-T5 (and also on T6 and T7) longer than those on adjacent sterna. Preabdominal sterna pale brown to ochreous. S1-S5 becoming distinctly wider posteriorly, S5 widest and largest.

Postabdomen. T6 distinctly shorter than T5, transverse; T7 yet shorter and also narrower than T6. S6 strikingly broad and transverse, wider but shorter than S5 and apparently larger than adjacent T6 and laterally almost reaching the latter; S7 only half length of S6, strongly transverse and laterally meeting with sides of T7 (Fig. 13 ); both S6 and S7 finely setulose. Apex of postabdomen obscured, only T8 discernible as small bare(?) sclerite (Fig. 13 ), less than half length of T7. Cercus not visible.

Figures

Figure 3. Protanthomyza grimaldii sp. nov., holotype male (Baltic amber). Head and thorax, left laterodorsal view. Photograph by J. Rohacek.

Figure 4. Protanthomyza grimaldii sp. nov., holotype male (Baltic amber). Head and thorax, left laterodorsal view. Scale bar: 0.3 mm. For abbreviations see p. 4.

Figures 1, 2. Protanthomyza grimaldii sp. nov., holotype male (Baltic amber) 1 entire specimen, left laterodorsal view 2 ditto, right lateroventral view. Body length ca 2.6 mm. Photographs by J. Rohacek.

Figures 5 - 9. Protanthomyza grimaldii sp. nov., holotype male (Baltic amber) 5 head, left sublateral view 6 base of left wing 7 right mesopleuron, sternopleuron and pteropleuron, lateral view 8 abdomen and haltere, right lateral view 9 terminalia, right lateral view. Scale bars: 0.5 mm (5); 0.3 mm (6 - 8); 0.1 mm (9). For abbreviations see p. 4.

Figures 10, 11. Protanthomyza grimaldii sp. nov., female paratype (Baltic amber) 10 entire specimen, subdorsal view 11 ditto, lateroventral view. Body length ca 2.9 mm. Photographs by J. Rohacek (adapted from Rohacek 2013 a, fig. 7 E, F).

Figures 12 - 14. Protanthomyza grimaldii sp. nov., female paratype (Baltic amber) 12 left wing (invisible parts omitted) 13 abdomen, right lateroventral view 14 right f 2, t 2 and mid basitarsus, anterior view. Scale bars: 0.5 mm (12), 0.3 mm (13, 14). For abbreviations see p. 4.