Periscelis (Periscelis) fugax, Roháček & Andrade, 2017

Roháček, Jindřich & Andrade, Rui, 2017, Periscelis fugax sp. nov., an overlooked European species of Periscelididae (Diptera), with notes on the morphology and terminology of terminalia, Acta Entomologica Musei Nationalis Pragae 57 (1), pp. 229-251 : 234-244

Periscelis (Periscelis) fugax sp. nov.

( Figs. 1–4 , 6–21 )

Type material: HOLOTYPE: J labelled:“ PORTUGAL: Porto: Valongo, Valongo , 41°09′33.4″N, 8°29′05.6″W, 50–100 m, R.Andrade leg.”, “ 10.x.2011, sweeping over bark of Quercus trees with sap runs” and “ Holotypus ♂, Periscelis (P.) fugax sp.n., J. Roháček & R. Andrade det. 2016” (red label) ( SMOC, intact) . PARATYPES: PORTUGAL: 9 JJ 10 ♀♀, same data as for holotype (4 JJ 4 ♀♀ including 1 J 1 ♀ with genit. prep. SMOC; 2 JJ 2 ♀♀ NMPC; 3 JJ 4 ♀♀ in RAP) ; 1 ♀ with same data but collected 26.ix.2011 ( RAP) ; 6 JJ with same data but collected 1.x.2011 (3 JJ SMOC, 3 JJ /1 J genit. prep./ RAP) ; 7 JJ 2 ♀♀ with same data but collected 4.x.2011 (4 JJ SMOC, 3 ♀♀ / 1 ♀ genit. prep./ RAP) ; 8 JJ 4 ♀♀ with same data but collected 14.x.2011 (2 JJ 2 ♀♀ / 1 J 1 ♀ genit. prep./ SMOC, 6JJ 2♀♀ RAP) ; Bragança: Bragança, Parâmio, Parque Natural de Montesinho , 41°53′54.0ʺN, 6°51′16.3ʺW, 780 m, 21.vi.2015, sweeping over bark of Quercus trees with sap runs, 1 J, R. Andrade leg. ( RAP) ; Portalegre: Marvão, Santa Maria de Marvão , 39°23′50.2ʺN, 7°21′52.3ʺW, 616 m, 21.ix.2014, sweeping over bark of Quercus pyrenaica trees with sap runs, 1J 1♀, Ana Gonçalves leg. ( ARGC) ; all specimens in SMOC and NMPC dried from ethanol and mounted on pinned triangular cards, those in RAP and ARGC retained in ethanol. CZECH REPUBLIC: C. Bohemia: Roztoky, Tiché údolí, Roztocký háj (5852), 50°8′47.5ʺN, 14°23′10.1ʺE, beer trap, 2.–10.ix.2009, 1 J, J. Preisler leg. ( SMLC) ; Český kras PLA, Na Voskopě res., 49°54′25ʺN, 14°04′05ʺE, beer trap, oak-hornbeam forest, 16.ix.–2.x.2016, 1 ♀, P. Heřman leg. ( JMB) ; S Moravia: Podyjí NP, Liščí skála, 48°49′52ʺN, 15°56′35ʺE, 410 m, Quercetum , 9.ix.– Malaise trap, 3.viii.–9.ix.2004, 1 ♀, 9.ix.–28.x.2004, 6 JJ 7 ♀♀, M. Barták & Š. Kubík leg. (2 JJ 4 ♀♀ MBP; 2 JJ 2 ♀♀ / 1J genit. prep. / SMOC; 1 ♀ JMB) ; Podyjí NP, Fládnická chata, 48°48′42ʺN, 15°58′03ʺE, 360 m, forest, 9.ix.–28.x.2004, Malaise trap, 2 JJ, M. Barták & Š. Kubík leg. ( MBP) ; Podyjí NP, Havrarníky , 48°48′52ʺN, 15°59′48ʺE, 330 m, forest-steppe, 1.–24.vii.2002, Malaise trap, 1 ♀, O. Meixnerová leg. ( MBP) ; Podyjí NP, Vraní skála, 48°51′03ʺN, 15°53′42ʺE, 390 m, mixed wood, 8.vii.–28.x.2003, Malaise trap, 1 J, O. Meixnerová leg. ( JMB) ; all dried from ethanol and mounted on triangular cards. All paratypes with yellow label “ Paratypus J (or ♀), Periscelis (P.) fugax sp.n., J. Roháček & R. Andrade det. 2016”

Diagnosis. A relatively large Periscelis species (2.45–3.8 mm) closely resembling P. winnertzii but somewhat smaller and differing from the latter in having antennal pedicel with smaller black spot (covering only dorsal half of its external side, Fig. 4 ); mesonotum grey with a distinct pair of medial brown stripes and scutellum more or less yellow on disc ( Fig. 3 ); male S6 suboblong, with narrow medial depression, brown pigmented only laterally ( Fig. 13 ); gonostylus shorter, with simple apex ( Fig. 9 ); postgonite with broad proximal part produced posteroventrally ( Fig. 8 , arrow); female T8 uniformly brown pigmented ( Fig. 16 ) and S8 brown margined both laterally and posteriorly ( Fig. 17 ).

Description. Male. Total body length 2.46–3.65 (holotype 3.41) mm. General colour brown, grey microtomentose and dull, with some parts of head, thorax and legs yellow to whitish variegated and abdomen with silvery white microtomentose spots in lateral margins of terga. Head longer ventrally than dorsally in profile ( Fig. 1 ), with face distinctly protruding in front of anteroventral eye margin, brown, ochreous and whitish variegated and almost all densely microtomentose and dull. Compound eye elongately ellipsoid to suboval with longest diameter oblique and 1.7–1.8 times as long as shortest, and exposing a large area of postgena-occiput at side of head; eye red when alive, with facets uniform and with sparse whitish interfacetal microsetulae. Occiput concave, brown with marginal parts yellow to whitish yellow on extended ventrolateral part; concave brown part with a pair of large silvery microtomentose areas. Frons largely bare, broad (about 1.6 times as wide as high), anteriorly only slightly narrower than posteriorly and its large medial disc distinctly depressed compared to orbits, light ochreous to pale brown medially, yellow to whitish yellow laterally (orbits in particular) and entirely microtomentose; ocellar triangle small, brownish (darkest of frontal structures), slightly elevated and situated at posterior margin of frons; ocelli relatively large, arranged in ipsilateral triangle. Face markedly darker than frons, largely brown to (ventrally) blackish brown, yellowish to ochreous only in shallow concavities below antennae and on carina, medially narrowly carinate and ventrally strongly produced above mouthedge. This protruding part tuberculate and slightly shining. Facial sensilla not developed but ventral part of face with 3–5 inclinate lateral setae on each side. Gena relatively low, brown anteriorly but becoming pale posteriorly; postgena and adjacent occiput expanded, ochreous to pale yellow. Antenna very slightly divergent and largely yellow, only pedicel with dull blackish dorsal spot covering laterally about half of its side ( Fig. 1 ). Pedicel relatively large, expanded dorsally ( Fig. 1 ) where it bears longer setae than laterally; 1st flagellomere elongate, with anterodorsal apex entirely covered by very short whitish pilosity; arista yellow, slightly longer than antenna, long-pectinate (longest rays longer than 1st flagellomere), dorsally with 4–5, ventrally with 2 long brown rays in addition to a number of short rays in its distal half. Mouthparts ochreous to pale brown; clypeus brown; palpus clavate, pale brown, with numerous short dark setulae.

Cephalic chaetotaxy: all setae blackish brown; pvt well developed (although shortest of frontal setae), divergent, situated between posterior ocelli at dorsal margin of occiput; vti robust, longest of cephalic setae, upright, very slightly inclinate; vte, oc and ors subequal in length, strong but distinctly shorter than vti; vte lateroclinate; oc strongly proclinate and very slightly divergent, arising ouside ocellar triangle; only 1 reclinate ors situated in middle of orbit; 1–3 microsetulae in front of ors; no vibrissa or pseudovibrissa but with 2–3 short ventro-reclinate setae on ventral side of vibrissal angle and anterior part of gena; 3–5 inclinate setae also on lateroventral margin of face; gena posteriorly to vibrissal part with a series of 5–6 thicker and longer ventroclinate peristomal setae, becoming shorter posteriorly; no genal seta; expanded part of postgena and occiput behind eye with numerous short setae being stronger near posteroventral eye margin; posteroventral angle of occiput with a cluster of setae, 2 longer than others; postocular setulae behind posterodorsal margin of eye numerous, dorsally in single, ventrally in 2–3 rows.

Thorax ( Figs 1 , 3, 4 ) slightly narrower than head, generally brown, densely microtomentose and dull, with some parts yellowish to white. Mesonotum with distinctive microtomentose pattern: grey with margins and a pair of medial vittae brown ( Fig. 3 ). Scutellum contrasting with mesonotum, pale ochreous to yellow on disc, with only sides brown darkened ( Fig. 3 ). Humeral callus (postpronotal lobe) whitish yellow to white; also narrow notopleural area lighter, yellowish particularly around posterior npl ( Figs 1 , 4 ). Pleural part of thorax largely brown, less microtomentose and subshining, with ochreous to whitish (anteriorly) band in the middle, extended from base of fore coxa to haltere ( Fig. 1 ). Sternopleuron (katepisternum) with ventral corner also paler to yellow. Mediotergite uniformly brown. Scutellum distinctly (basally) wider than long, rounded trapezoidal; subscutellum reduced, dark brown.

Thoracic chaetotaxy ( Fig. 3 ): all setae and setulae blackish brown; ac setulae numerous, in 8 rows on suture, with 4 rows reaching almost to scutellum, none of them enlarged; 2 strong postsutural dc, the anterior half length to two-thirds of the more robust posterior, 8–11 dc setulae in front of anterior dc but no setulae between dc setae; 1 strong hu (postpronotal) seta plus 4–5 setulae on humeral callus; 2 strong npl, anterior as long as hu, posterior shorter; 1 sa (as long as hu) and 1 shorter pa; 2 sc, apical as long as posterior dc, laterobasal shorter than anterior dc; 1–3 (usually 2) fine setulae between apical sc but they can often be broken off; 1 short but distinct ppl; anepisternum with a group of short setulae in posterodorsal corner; 2 stpl (katepisternal) setae, anterior always shorter, numerous setulae on disc and 3–4 longer but fine setae on ventral corner of katepisternum.

Wing ( Fig. 2 ) relatively broad, with pale brown membrane darker fumosely spotted in some parts and ochreous to dark brown veins. Wing pattern is characterized by infuscation of distal part of cell r 2+3, around apex of R 4+5, area around r-m, M between r-m and dm-cu, around basal part of CuA 1 and of entire alula. Veins are darkened in all these parts and also distal half of R 1 and A 1 are dark brown. C not interrupted, uniformly setulose, reaching to apex of R 4+5. Sc short, ending free in subcostal cell but its curvature to C indicated by venal fold. R 2+3 long, very slightly bent to sinuate, ending closer to apex of R 4+5 than M. R 4+5 straight to indistinctly sinuate and terminating in wing apex. Distal part of M apically slightly recurved, diverging from R 4+5. Cross-vein r-m situated in distal half of dm cell; cross-vein dm-cu present but attenuated or even interrupted by spurious vein. CuA 1 distally slightly bent, ending near wing margin. Cells bm and cup developed, veins in the latter are attenuated. A 1 distinct but not reaching wing margin. Alula relatively large, dark, with marginal ciliation as long as that of anal lobe of wing. Wing measurements: length 2.78–3.61 (holotype 3.61) mm, width 1.03–1.29 (holotype 1.24) mm, Cs 3: Cs 4 = 0.44–0.58, rm/dm-cu: dm-cu = 1.48–1.88. Haltere with yellowish stem and relatively large, dirty white, knob.

Legs ( Figs 1 , 4 ) yellow or yellowish white and brown variegated on fore coxa (with ventral part pale yellow) and all femora, tibiae and tarsi; setosity brown. Extent of dark areas seems to be variable, particularly on femora. Generally f 1 and f 2 have two (often incomplete) brown rings, a paler ring basally and a darker ring subapically (with knees yellow) while f 3 is brown along most of its length dorsally with complete ring subapically leaving knee and ventral basal portion yellow. All tibiae have two brown rings, a proximal below knee and a distal subapically but t 1 has distal ring longer, almost reaching apex of tibia. Tarsi are yet lighter, yellowish white to (fore tarsus) white, each with 2 distal segments brown. Chaetotaxy: f 1 with a series of 6–8 long and thicker posteroventral setae and with a double row of shorter and finer upright posterodorsal setae; f 2 posteroventrally with a row of numerous fine setae (longest about three-fourth of maximum width of femur); t 1 with 1 slightly longer posterodorsal seta; t 2 with 1 distinct and thicker ventroapical seta (about as long as maximum width of tibia); remaining parts of legs uniformly setulose, without peculiarities.

Abdomen relatively broad, subovoid in dorsal outline ( Fig. 3 ), dorsally brown and yellow, ventrally pale ochreous to dirty yellow. T1+2 as long as T3 + T4, with boundary between T1 and T2 dorsomedially well delimited. T1 largely, T2 dorsomedially dirty yellow. T3–T5 broad and strongly transverse, bent laterally onto ventral side, becoming narrower posteriorly and each brown, with a blackish transverse band in front of posterior margin and white, silvery microtomentose spot on each side ( Figs 3, 4 ). All preabdominal terga shortly setose, with longest and thickest setae in posterolateral corners. Preabdominal sterna (S1–S5) relatively large (hence membrane between terga and sterna small), broad, more or less transverse. S1 shorter and wider than S2, pale yellow with darker posterior marginal stripe; S2 almost completely yellow to pale ochreous; S3–S5 subequal, of similar shape to S2 but laterally brownish. S2–S5 with scattered short fine setosity. Abdominal spiracles (1–6) in membrane close to lateral margins of terga.

Postabdomen: T6 relatively large, although narrower and somewhat shorter than T5, transverse but tapered posteriorly, setose similarly and also bearing lateral silvery spots as have T3–T5 ( Fig. 4 ). S6 (= pregenital sternum, Fig. 13 ) narrower and paler than S5, suboblong, with sparse setae at posterior margin and with distinct posteromedial narrow depression. In front of epandrium there is a virtually symmetrical arch-shaped synsclerite formed probably by fusion of T7, S7 and S8. This synsclerite is shortly setose only in posterior half and has embedded 7th spiracles in its lateral parts.

Genitalia ( Figs 6–12, 14 ). Epandrium relatively small, brown, wider than high, in form of an arch-like sclerite, with large anal opening ( Fig. 11 ), uniformly setose at posterior margin, anteriorly projecting in a long process – surstylus ( Fig. 6 , ss) on each side. Cerci large, long, elongate, longer than epandrium ( Fig. 6 , ce), relatively distant from each other, with apex tapered and slightly incurved ( Fig. 11 , ce), with rich but rather uniform setosity along all its length and some micropubescence posteriorly ( Fig. 10 ). Surstylus ( Figs 6, 7 , 12 , ss) proximally wider, distally tapered, slender, finely setulose mainly at outer side, with apex rounded in lateral view ( Fig. 7 ), somewhat lanceolate in anterior view ( Fig. 12 ). Gonostylus ( Figs 6, 9 , 11, 12 , gs) much shorter than surstylus, rod-like, tapered distally, having apex simply rounded, with a group of microsetulae. Bases of gonostyli are medially movably attached to medandrium ( Figs 11, 12 , ma) which is reduced to a small transverse and bare sclerite. Hypandrium ( Fig. 6 , hy) formed by symmetrical slender frame-like structure, which is dorsally firmly fused to ventral parts of expanded phallapodeme and posteriorly reaching to medandrium where (posteromedially) it is open or membranous. Hypandrial frame bare and without appendages (pregonites). Aedeagal complex ( Fig. 6 ) symmetrical, markedly larger than epandrium. Phallapodeme ( Fig. 6 , pha) bipartite, peculiarly enlarged, composed of a voluminous pocket-shaped sclerite bulging anterodorsally and ventrolaterally fused with hypandrium and a short, well-sclerotized and ventromedially forked basal sclerite (Figs, 6, 14, bpha) attached to the former cup-like sclerite. Aedeagus simple, without disparate phallophore being reduced or undeveloped ( Figs 6 , 14 ) and largely formed by a very long, ribbon-shaped, submembranous distiphallus which is partly hidden in a pocket of the phallapodeme ( Fig. 6 ); apex of distiphallus flat, denticulate on tip. Postgonite ( Figs 6, 8 , pg) relatively robust, larger than gonostylus, proximally dilated, expanded posteroventrally, distally slender, digitiform, with a series of microsetulae along posterior margin. Ejacapodeme ( Fig. 6 , ea) free, large but shorter than phallapodeme, rod-like but proximally widened and distinctly forked.

Female. Similar to male unless mentioned otherwise. Total body length 2.78–3.74 mm. Head distinctly lighter coloured: frons largely yellow, or only medially ochreous, thus only ocellar triangle brownish; face entirely (also ventrally) whitish yellow, at most with ochreous tinge at vibrissal angle; the latter pale brown but rest of gena ochreous to (more posteriorly) yellow. f 2 uniformly setulose, without posteroventral row of longer setae. Wing measurements: length 3.05–3.77 mm, width 1.15–1.43 mm, Cs 3: Cs 4 = 0.41–0.50, rm/dm-cu: dmcu = 1.38–1.78. Abdomen broader than in male, with preabdominal terga T3–T5 uniformly brown, lacking blackish transverse bands. Preabdominal sterna (S1–S5) similarly coloured and setose as in male but somewhat more transverse and lateral darkening of S3–S5 often less distinct (cf. Fig. 20 ).

Postabdomen ( Figs 15–17, 20, 21 ) broad anteriorly, strongly tapered posteriorly. T6 large, flat, with lateral part somewhat bent ventrally, brown, with well developed lateral white and silvery microtomentose spots ( Fig. 15 ), finely setose in posterior half and laterally (setae longest). S6 simple ( Fig. 20 ), transversely suboblong, smaller (particularly shorter) than S5, ochreous with lateral darkening and sometimes with a pair of diffuse darker spots on disc, with 2 pairs of longer setae at posterior margin besides short setosity. 6th spiracle in membrane very close to margin of T6 ( Fig. 20 ). T7 and S7 fused to form ring-shaped tergosternum T7+S7 ( Figs 15, 20, 21 ) which is brown except for pale ventromedial part; ventrally with more setae than dorsally, with longest setae at posterior margin laterodorsally. 7th spiracle situated laterally, in T7+S7 ( Fig. 21 ). T8 forming a bent, relatively narrow brown sclerite ( Fig. 16 ), finely but relatively long setose in posterior two-thirds. S8 ( Fig. 17 ) separate, about as wide as T8 but slightly shorter, densely setose on entire disc, yellow with characteristic brown darkening along lateral and posterior margins. Genital chamber membranous, elongate, without sclerotized structures; ventral receptacle ( Fig. 19 ) submembranous, digitiform but distally dilated, having regularly finely striated slender proximal part and somewhat tuberculate distal widening, the latter with a tail-like, apically attenuated and twisted projection. Spermathecae (1+2) globular ( Fig. 18 ), blackish brown and heavily sclerotized; a pair borne on common duct often larger than single one; spermathecal ducts long and relatively broad, internally strengthened by spiral structure; the terminal fork connecting 2 spermathecal bodies very short. T10 (supraanal plate) absent ( Fig. 21 ). S10 (subanal plate) reduced ( Figs 20, 21 ), short, crescent-shaped, weakly sclerotized and pale-pigmented, covered by micropubescence and with 2–3 minute setulae posterolaterally. Cercus ( Figs 20, 21 ) relatively small, short, subovoid, with rich fine setae and fine micropubescence; apical seta longest, as long as cercus.

Etymology. The new species is named fugax because one of the meanings of this Latin adjective is „passed unnoticed“ to reflect the fact that species has been so long overlooked.

Relationships. Periscelis fugax sp. nov. has formerly been mixed with the very similar P. winnertzii Egger, 1862 which undoubtedly is its nearest known relative. According to PAPP & WITHERS (2011) P. winnertzii has no close ally among Palaearctic species of Periscelis (which they interpret as a genus in a narrower concept, i. e. without other subgenera). Despite the fact that there is now an additional species, P. fugax sp. nov., having similar venation and structures of the male and female genitalia, we agree with them, that this species-pair does not deserve to be classified in their own supraspecific taxon as did ENDERLEIN (1936) for P. winnertzii establishing for it a separate genus Parclioscena Enderlein, 1936 .

The sister-species relationships of P. fugax and P. winnertzii are demonstrated by their close resemblance in both external features and structures of the male and female terminalia. The (formerly undescribed) sexual dichroism of face (ventrally dark brown in male but yellow in female) can be a synapomorphy of this species pair. In the male genitalia two further putative synapomorphies are found: (1) gonostylus with microsetulae restricted to apical part and (2) cercus with relatively short setae on apex. In the female terminalia no synapomorphy can be revealed because these structures remain undescribed in other species of the subgenus.

Biology. The species seems to be associated with sap runs of oaks because the majority of type specimens were collected in this habitat (cf. also ROHÁČEK et al. 2016, as P. sp. cf. winnertzii ), thus living similarly to P. winnertzii (see below). Interestingly, P. fugax has hitherto not been found to co-occur syntopically with P. winnertzii although both species can apparently be sympatric (confirmed for Portugal). Almost all specimens examined were found in September–October, only singletons in June, July and August.

Distribution. Periscelis fugax is probably widespread in Europe: it has hitherto been recorded from Portugal and Czech Republic (both Bohemia and Moravia) but is surely also living in intervening areas. It has previously been recorded from the Czech Republic (Podyjí NP) by MÁCA et al. (2005) under the name P. winnertzi , see the type material. Two of the specimens recorded by ROHÁČEK et al. (2016) as P. sp. cf. winnertzii from Portugal were subsequently found not to belong to P. fugax but to true P. winnertzii (see material examined under that species).

Figures

Figs 1–2. Periscelis (P.) fugax sp. nov. 1 – male holotype, body length ca 3.4 mm; 2 – wing, length 3.1 mm, male paratype (Portugal: Valongo). Photo by J. Roháček.

Figs 3–5. Periscelis species. 3 – Periscelis (P.) fugax sp. nov., male paratype, body dorsally, length ca 3.0 mm (Czech Republic: S. Moravia); 4 – same specimen, laterally; 5 – Periscelis (P.) winnertzii Egger, 1862, male, head and thorax subdorsally, body length ca 4.1 mm (Hungary). Photo by J. Roháček.

Figs 6–10. Periscelis (P.) fugax sp. nov., male paratype (Portugal: Valongo). 6 – entire genitalia, laterally; 7 – surstylus, laterally; 8 – postgonite, laterally; 9 – gonostylus, sublaterally (widest extension); 10 – cercus, laterally.Scale = 0.1 mm. For abbreviations see p. 231.

Figs 11–14. Periscelis (P.) fugax sp. nov., male paratype (Portugal: Valongo). 11 – external genitalia caudally (surstyli omitted); 12 – same, cranially (cerci omitted); 13 – pregenital sternum (S6), ventrally; 14 – aedeagal complex, laterally (only basal part of distiphallus depicted). Scale = 0.1 mm. For abbreviations see p. 231.

Figs 15–21.Periscelis (P.) fugax sp. nov., female paratype (Portugal:Valongo). 15 – postabdomen, dorsally; 16 – T8, dorsally; 17 – S8, ventrally; 18 – spermathecae; 19 – ventral receptacle, laterally; 20 – 5th segment and postabdomen, ventrally; 21 – posterior part of postabdomen (from 7th segment), laterally. Scales = 0.2 mm (Figs 15, 20, 21) and 0.1 mm (Figs 16–19). For abbreviations see p. 231.