Babakintaromyia albitarsis, Saigusa, 2024

Saigusa, Toyohei, 2024, A remarkable new genus of Sciomyzoidea from Japan, with discussion of its taxonomic position (Diptera, Acalyptratae), Zootaxa 5519 (4), pp. 549-560 : 550-555

Babakintaromyia albitarsis sp. nov.

( Fig. 1A, B )

Type material. HOLOTYPE ♂, labelled: [Aomori, Japan], Kawaratai (Ookawagoe) [40°31′21″N 140°14′05″E], Nishimeya Village, July 2, 2010, T. Nakamura leg.; [HOLOTYPE], Babakintaromyia albitarsis Saigusa, 2024 .

PARATYPES: Each specimen with a paratype label: “[PARATYPE] Babakintaromyia albitarsis Saigusa, 2024 ”. [HONSHU]: (AOMORI Pref.) 2♀, Otoshino-sawa [41°17′59″N 141°10′05″ E 57 m], 12.vii.2003, S. Araki (1♀ collected in flight interception trap, both wings removed and glued on cards) (1♀ in CNC) ; 1♂, same data as holotype (in CNC) ; 1♀, Kuromori ([Yûsandû]) [40°40′36″N 140°11′34″E 293 m], Ajigasawa Town , 20– 27.vi.2023, MT, T. Nakamura leg. ; (IWATE Pref) 1♀, [Iwate, Japan], Toshichi Spa [39°56′40″N 140°51′40″E 1370m], Hachimanntai City , 5.viii.2015, D. Katô leg. ; (NIIGATA Pref) 1♂, same data as holotype ; 4♂, Kurokawa [38°3′56″E 139°27′37″E, 114m], N-Echigo , 24.vii.1971, Col. K. Baba / Sciomyzidae ?, Det. J.F. McAlpine 1985/ New subfamily of Dryomyzidae, Steyskal (1♂, body dissected in vial, one wing missing after photograph taken ; 1♂, abdomen removed, dissected in vial) ; 1♂, Natsui [38°02′26″N 138°29′13″E, 135 m], Kurokawa-mura , 3.vii.1985, K. Konishi leg. ; (IBARAKI Pref) 1♂, [Sekimoto-cho Sadanami] [36°56′24″N 140°35′13″E, 645 m], Kitaibaraki-city. 19.vi.2005, K. Ichige leg. ; 1♀, [Sekimoto-cho Sadanami] [36°56′24″N 140°35′13″E 645 m] (Malaise Trap), Kitaibaraki-city. , 19–25.vi.2005, K. Ichige leg. ; (ISHIKAWA Pref) 1♂, Mt. Hakusan , on forest path [36°6′56″N 136°42′34″E, 940 m], 9.vii.1983, I. Togashi (in the Natural History Museum) ; (NAGANO Pref) 1♀, Matsumoto City, Horigane Karasugawa Mt. Nabekanmuri , 2100–2200 m Time Zones 09:30–12:30, GPS: 36°16′19″N, 137°47′44″E, 4.viii.2013, T. Sasai leg. ; 1♀, Daimyôzin stream [36°31′10″N 138°21′8″E, 1273 m], Sugadaira MRC, 16.vii.2021, D. Katô leg. ; (SAITAMA Pref) 1♀, Chichibu-shi, Terao [35°59′38″N 139°3′27″E, 300 m], 12.vi.2021, T. Tago ; (KYOTO Pref) 1♀, Kurama [35°6′48″N 135°40′20″E, 277 m], 4.vi.1933, Col. T. Kimura (abdomen removed, dissected in vial) . [SHIKOKU]: (EHIME Pref) 1♂, Sakaide, Kasayama mountain food [34°18′30″N 133°51′37″E, 42.6 m], 10.v.1955 . [KYUSHU]: (MIYAZAKI Pref) 1♂, Kobayashi c., Inokodani , 27.v.2003, 32°06′57″N, 131°00′35″E, R. Matsumoto leg .

The holotype and most paratypes are preserved in the Kyushu University Museum , Fukuoka. A male and a female paratype will be donated to the CNC (Ottawa) and a male paratype to The Natural History Museum (London), are indicated in parentheses.

Description. Male ( Fig. 1A ). Size: Body length 10.0– 12.7 mm; relative length of abdomen to thorax 1.3–1.6; wing 10.5–12.5 mm. Black to blackish brown and black setose.

Head ( Fig. 2C ) in lateral aspect subtriangular, almost straight from vertex to lunule, tapered to oral margin and only slightly convex on dorsal half of occiput. Compound eye moderately large, bare, 3/4 as long as high, 2/3 as high as head, with longer axis more or less oblique. Frons ( Fig. 2A ) flat, slightly wider than 1/2 of head width; polished black ocellar tubercle and narrow triangular region on vitta around tubercle tapered to narrow point shortly beyond middle of frons, otherwise frons densely and thickly black pruinose, evenly clothed with short erect to suberect setulae; without distinct orbital plates or fronto-orbital setae; becoming dark reddish brown towards lunule. Lunule well developed, 2/3 as wide as frons; blackish brown, polished. Ocellar area ( Fig. 2F ) with short setae of which 1–2 sometimes bristle-like; 2–3 pairs of convergent short postocellar setae accompanying a few short setulae; inner vertical setae short, incurved; postverticals longer than inner verticals. Face ( Fig. 2B ) broad, represented by polished triangular area from oral margin to near antennal sockets; face not produced forward near oral margin; parafacial areas dark brown, densely pruinose, without setae. Antennal sockets approximated with each other, separated by distinct narrow keel. Gena silvery pollinose including postocular area, 1/3 as wide as head height, clothed with short setulae spreading to ventrolateral area of face, without strong setae; vibrissa lacking. Occiput polished black, densely clothed with longish setae, longer towards lower margin of gena; lateral margin of occiput distinctly carinate along compound eye to peristomal margin.

Antenna ( Fig. 2G ) 3/4 as long as head; scape black, very short, as long as wide, bearing minute setulae; pedicel brown, as long as scape, densely clothed with short black setulae with short dorsal seam on distal 1/3. Postpedicel (first flagellomere) dark brown, sparsely covered with greyish pollinosity; elongated, somewhat compressed laterally, 2.7X as long as scape and pedicel combined, 3.1–3.6X as long as basal width, gradually tapered to rounded apex. Arista yellowish brown to yellow, slender, 1.4X as long as postpedicel, arising from subbasal part of dorsal surface of postpedicel; aristomere 1 very short, socket-like; aristomere 2 twice as long as wide, both bare; aristomere 3 (apical part) as thick as aristomere 2 basally, becoming very fine and minutely setulose apically.

Clypeus ( Fig. 1C ) small, narrow, U-shaped, 1/3 as wide as oral cavity, widely separated from anterior margin of face by wide membranous area, with basal margin weakly expanded anteromedially; clypeus deeply sunken in peristomal area as to be invisible in profile.

Mouthparts ( Fig. 1C, D, E ) small, distance from base of mentum to distal margin of labella in macerated condition slightly shorter than head height; palpus small and oblong, 1/4 as long as head, 3X as long as wide, setulose dorsally; labrum very small, 1/3 as long as prementum, 1.5X as long as wide; hypopharynx slightly longer than labrum; prementum small, slightly longer than twice width, widest subbasally, tapered to narrow distal margin, bearing pair of setae near basal margin and pair of setae and a few shorter setae at middle; palpus light brown, black setose; prementum brown with several black setae; labella in macerated condition as long as entire length of proboscis, with more than 25 pseudotracheae on each side.

Thorax ( Fig. 2D ) moderately elongated; black to blackish brown; postpronotum and mesoscutum dark brown to black pruinose; mesoscutum with pair of blackish stripes surrounded by more greyish ground, stripes disappearing slightly beyond transverse suture; sides of mesoscutum darker; scutellum roundly pointed apically. Prothorax: antepronotum bare, extremely narrow longitudinally placing head very closely to thorax; postpronotum (humerus) clothed only with short setulae, with longer setulae posteriorly; prosternum ( Fig. 2I ) narrow and bare, widening anteriorly, isolated from proepisternum; proepisternum bearing a few minute setulae on ventral section, without strong setae; proepimeron bare. Mesonotum, including scutellum, rather flat, evenly and densely clothed with short setulae; acrostichals absent; 1 short prescutellar dorsocentral seta; notopleural area with row of 2–4 setae, longer on posterior area, with several short setae; supra-alars absent; postalar callus with 1–3 postalar setae variable individually in length and thickness; scutellum with pair of closely set short apical setae (one male paratype with additional pair of setae on mid-sublateral portion of scutellum). Anepisternum bare, katepisternum evenly clothed with short setulae, without strong setae; anepimeron bare; several minute setulae below and behind posterior spiracle.

Legs ( Fig. 2E ) long, rather slender; black to dark brown; tarsomere 1 (metatarsus) of all legs characteristically white in contrast to black tibiae and more apical tarsomeres; tarsomere 2 slightly paler than tarsomeres 3–5; coxae densely silvery pruinose; femora pale to yellowish white towards base, pale area obscure on fore femur, basal 1/5 on mid femur and basal 1/4 on hind femur. Fore femur more or less swollen basally, hind femur slender; tibiae slender, more or less constricted on basal 1/4; trochanters simple. Legs evenly clothed with short black setae, slightly longer on coxae; fore femur with several short posteroventral bristles; hind femur bearing row of short anteroventral and posteroventral bristles on apical 1/2. All tibiae short setose, gradually thickened on apical 1/2 of fore and mid tibiae; hind tibia slender on basal 1/4, then abruptly thickened beyond apical 3/4, there twice as thick as basal part; fore and mid tibiae with several apical weak setae; without prominent setae including preapical dorsal seta (as found in most or all species of Sciomyzidae ); occasionally fore and (or) mid tibiae with preapical dorsal seta (often present on only one tibia, rarely both), slightly longer and thicker than surrounding setae, but never strong as in sciomyzid species. Tarsus short black setose; tarsomere 1 slender, fore and mid tarsomere 1 densely clothed with yellowish setulae ventrally; tarsomere 2 often slightly paled; tarsomeres 2–5 flattened, and apically widened on tarsomeres 3–5. Lengths of leg segments as in Table 1 .

Wing ( Fig. 2H ) rather elongated, 3.0–3.3X as long as wide, slightly infuscated apically, veins dark brown; cell c, basal 1/2 of cell br, entire cell bm and cell cua bare, without microtrichia; pterostigma narrow and pale brown in cell sc distal to tip of vein Sc; axillary incision deep, alula well developed; Costa complete, without breaks, extending to tip of M 1; Sc complete, ending in basal 1/3 of costa; R 1 setulose towards tip; R 4+5 arched anteriorly and distally convergent toward M 1; cell r 4+5 widest at level of discal crossvein, greatly tapered to both crossvein r-m and wing tip; cell bm 1/2 as long as cell br, separated from discal cell; crossvein r-m usually near middle of cell dm, where vein M 1 weakly angulate; discal crossvein only slightly oblique and posterodistal corner of discal cell slightly acute; apical section of M 4 0.3–0.5X as long as discal crossvein, with apex of M 1 ending slightly before wing margin; cell cua (anal cell) long and wide, longer than cell bm, widened distally, sharply produced distally and pointed at posterodistal corner; distal margin of cell cua (middle section of vein CuA) weakly angulate at middle; CuA+CuP (anal vein) somewhat weakened apically, complete to wing margin. Halter pale brownish to yellowish white.

Abdomen ( Fig. 2J ) elongated and slender, weakly curved ventrally in dried specimens; 1.3–1.6X as long as thorax (direct distance from dorsal surface of abdominal base to terminalia), evenly clothed with short setae; terga 2–5 short rugose with numerous fine transverse wrinkles, short setose; sternum 1 bare; sterna 3–5 simple, short setose, weakly emarginate along posterior margin. Posterior margin of tergum 5 almost straight; broad intersegmental membranous area posterior to tergum 5 nearly 1/3 as long as tergum 5.

Main part of pregenital segments ( Fig. 3 ) large, hood-like (protandrium of Steyskal (1965)), connected to epandrium posteriorly; main part of protandrium consisting of sterna 7 and 8, with former mostly represented by anterior submarginal ridge of protandrium. Tergum 6 ( Fig. 3C, E, F ) represented by small sclerite just dorsal to left spiracle of segment 6, with weakly sclerotized, narrow, and pale transverse wrinkle running towards right on intersegmental membrane between segment 5 and protandrium; wrinkle more deeply pigmented and prominent near right anterior corner of protandrium ( Fig. 3F ); right spiracle of segment 6 ( Fig. 3D, F ) present on membranous area. Sternum 6 ( Fig. 3D, E ) moderately large, with posterodorsal area fused with sternum 7 for short distance, widened obliquely and subventrally, occupying main anterior area of ventral surface of pregenital segments; as stated above, sternum 6 partly united with anterior margin of sternum 7 and then ventrally separated from latter by narrow membranous area on ventral surface. Sternum 7 ( Fig. 3D, E ) with posterodorsal margin fused with left anterior area of protandrium (border between two parts hardly recognizable), with dorsal extremity continuing to transverse ridge on anterior submargin of protandrium. Ridge encircling left spiracle ( Fig. 3B, C ) of segment 7 near right anterior corner of protandrium. Lateral area of sternum 7 enlarged subventrally as sternum 6, becoming very narrow ventrally, continuing to element of tergum 7 extending from right anterior corner of protandrium ( Fig. 3D, F ). Tergum 7 ( Fig. 3C ) appearing as submarginal ridge of protandrium right of left spiracle of segment 7, extending right to anterior area of protandrium and continuing ventrally as narrow sclerotized band completely fused with narrow ventral extremity of sternum 7 ( Fig. 3D, F ); tergum 7 (fused with sternum 7) ventrally unrecognizable as independent sclerite, seeming to occupy posteroventral area of segment 7 (so that this area may be interpreted as syntergosternite 7) with right spiracle ( Fig. 3D ) of segment 7. Tergum 8 ( Fig. 3D ) represented by strongly sclerotized narrow transverse black stripe on ventral membranous area anterior to hypandrium, with lateral extremities close to lateral margins of protandrium; left area much constricted so that stripe appears divided into longer left part and shorter right part. Sternum 8 hood-like, occupying main element of protandrium, connected posteriorly with epandrium.

Hypopygium ( Fig. 4 ): Moderately large, polished black and bare. Epandrium ( Fig. 4A, B ) large, black, thinly pruinose at side and apical part, fine longish black setose; anterolateral corner produced to triangular projection loosely connected with anterior projection of lateral part of hypandrium. Posterior surstylus ( Fig. 4A, B ) large, lamellate, blackish brown to brown, thinly pruinose, short setose along inner margin; slightly shorter than height of epandrium, 3X as long as basal width, widened on apical half towards rounded terminal margin; basal margin of outer wall separated from lateral margin of epandrium by narrow membranous slit, inner surface bearing spinules; anterior surstylus ( Fig. 4B, C, D ) small, apically bifid into shorter anterior and longer posterior processes, bearing dense spinules slightly larger than those on posterior surstylus; tightly connected with sublateral margin of epandrium ventral to posterior surstylus; sclerotized band arising close to dorsal part of anterior surstylus and extending dorsally close to inner base of posterior surstylus. Hypandrium ( Fig. 4E, G, F ) narrow ventrally, widened laterally towards apex, connected with posterolateral corner of epandrium by small anterior projection and articulated dorsally with lateral margin of roof-like subepandrial sclerites; dorsolateral margin of hypandrium fused with pregonite, leaving distinct ridge along fused line; pregonite represented by simple lamella covering postgonite and phallobase; postgonite smaller than pregonite, lamellate and covering phallobase; phallapodeme very long ( Fig. 4E, F ), basally articulated with lateral margins of basiphallus; short gutter-like sclerite from ventral part of base of phallapodeme. Phallus ( Fig. 4E, F, G ) with small, circular, ring-like basiphallus connected dorsally with minute sclerite, positioned between postgonites; distiphallus ( Fig. 4E, G ) connected to basiphallus, more or less membranous dorsally on basal area, moderately long, ribbon-like, more or less twisted apically, with dense, setula-like short processes on one margin; ejaculatory apodeme L-shaped, elongate, as long as phallapodeme. Cercus ( Fig. 4A, B, C ) lobate, rather small, elongated dorsoventrally, droplet-shaped in posterior aspect; finely setose, outer basal margin weakly produced medially; each cercus laterally with weakly sclerotized small sclerite.

Female ( Fig. 1B ). Similar to male except as follows: body 12.8–14.5 mm; abdomen 1.6–2.0X length of thorax; wings 11.7–12.0 mm. Abdomen ( Fig. 5A, B ) weakly curved ventrally, 1.6–2.0X as long as thorax (direct distance from dorsal surface of abdominal base to terminalia); gradually tapered beyond middle except beyond segment 7; terga 1–5 thinly pruinose, posterior terga polished; terga and sterna short setose, subrectangular; terga and sterna on each segment distinctly separated by pleural membranous area except anteriorly on segment 7 where sclerites closely approximated and not well differentiated. Spiracles all on pleural membrane close to lateral margins of terga, with spiracles of segment 7 more or less on sclerotized pleural area close to anterolateral corner of tergum 7. Sternum 8 ( Fig. 5C, D ) narrow, densely short setose, overlapping hypoproct posteriorly; hypoproct circular, somewhat concave medially and short setulose; epiproct small and setulose; cercus ovate and small, short setulose, without long setae. Pair of spermathecal ducts ( Fig. 5E ) extending anteriorly from genital chamber; each duct terminating in pair of spermathecae; in single dissected female, one pair of spermathecae almost spherical ( Fig. 5F ) and other pair oval ( Fig. 5G ), twice as long as diameter of spherical pair; diameter of spherical spermatheca 80 μm, longer diameter of oval spermatheca 200 μm and shorter diameter 95 μm; length of spermathecal duct about 1500 μm.

Etymology. Babakintaromyia albitarsis sp. nov. is named after the white tarsomere 1 (and 2) of all legs.

Distribution. Palaearctic Japan (Honshu, Shikoku, Kyushu).

Remarks. Babakintaromyia gen. nov. is distinguished easily from the morphologically similar sciomyzid genus Salticella by many characters including the less bristly body, the slender rather than stout hind femur, and absence of a distinct preapical dorsal seta on the tibiae. The pregenital segments also are somewhat similar to those of Salticella , but tergum 6 is more atrophied and divided into minute sclerites (in Salticella represented by an undivided narrow transverse sclerite), and tergum 8 more clearly sclerotized (weakly sclerotized and more remnantlike in Salticella ).

Biology. This species has been very rarely collected. Although I have collected Diptera extensively for more than 60 years in Japan, I have never discovered this species. Biological data of this species are very scanty. Most specimens have been collected in woods, with some collected along mountain streams. Two males (holotype and one paratype) sitting on a tree trunk of Albizia julibrissin ( Fabaceae ) at Nishimeya village in Aomori Pref., Honshu, were collected by T. Nakamura. A female (paratype) sitting on a tree trunk of a dead, still standing Magnolia ovobata ( Magnoliaceae ) at Sugadaira in Nagano Pref., Honshu, was collected by D. Kato. Some specimens were collected by use of sweep nets or flight interception traps in woods, mostly near a brook. Regrettably, no information as to immature stages of this species is known.

Figures

FIGURE 1. Babakintaromyia albitarsis gen. et sp. nov., adults and mouthparts. A, male; B, female; C, mouthparts (macerated), anterior aspect; D, ditto, lateral aspect; E, ditto, anterodorsal aspect (clp, clypeus; hpp, hypopharynx; lb, labrum).

FIGURE 2. Babakintaromyia albitarsis gen. et sp. nov., body parts of male. A, head, dorsal aspect; B, ditto, anterior aspect; C, ditto, lateral aspect; D, thorax, lateral aspect; E, legs (macerated); F, vertical area of head, anterior aspect; G, antenna (macerated); H, wing; I, prosternum; J, posterior half of abdomen (macerated), lateral aspect (iv, inner vertical bristle; cx1, fore coxa; rp1, right foreleg; lp2, left midleg; rp3, right hindleg; prst, prosternum; pv, postvertical seta).

FIGURE 3. Babakintaromyia albitarsis gen. et sp. nov., pregenital segments of male. A, left lateral aspect; B, right lateral aspect; C, dorsal aspect; D, ventral aspect; E, anterior area, left lateral aspect; F, ventral area of left side on intersegmental area, ventral aspect (lsp6, left spiracle of segment 6; lsp7, left spiracle of segment 7; rsp6, right spiracle of segment 6; rsp7, right spiracle of segment 7; st5, sternum 5; st6, sternum 6; st7, sternum 7; st8, sternum 8; tg5 tergum 5; tg6, tergum 6; tg7, tergum 7; tg8, tergum 8).

FIGURE 4. Babakintaromyia albitarsis gen. et sp. nov., male hypopygium (macerated). A, hypopygium, lateral aspect; B, cut right epandrium with surstyli, inner aspect; C, hypopygium, posterior aspect; D, epandrium with surstyli, posterior aspect; E, ventral part of hypopygium, lateral aspect; F, ditto, inner aspect; G, phallus, lateral aspect (ass, anterior surstylus; bph, basiphallus; cer, cercus; dph, distiphallus; ejap, ejaculatory apodeme; ejd, ejaculatory duct; ep, epandrium; ses, subepandrial sclerite; hp, hypandrium; pep, anterolateral process of epandrium; phap, phallic apodeme; prg, pregonite; pss, posterior surstylus; psg, postgonite).

FIGURE 5. Babakintaromyia albitarsis gen. et sp. nov., female terminalia. A, posterior part of abdomen, ventral aspect; B, ditto, lateral aspect; C, ditto, enlarged; D, apical part of abdomen, ventral aspect; E, spermathecae and spermathecal ducts (white arrows); F, spherical spermathecae; G, oval spermathecae (cer, cercus; st7, sternum 7; st8, sternum 8; hyp, hypoproct; tg8, tergum 8; epp, epiproct).