Ptiolina Zetterstedt, 1842

Kerr, Peter H., 2010, 2592, Zootaxa 2592, pp. 1-133 : 95-96

Genus Ptiolina Zetterstedt

Figs. 15–16, 54–55, 77–78, 99–100, 121, 145–147, 181–183.

Ptiolina Zetterstedt 1842: 226 . Type species Leptis obscura Fallén 1814 , by subsequent designation of Frauenfeld 1867: 497. See notes below.

Eurytion Jaennicke 1867: 99. Type species Eurytion paradoxus Jaennicke 1867 , by monotypy.

Tyolina Walker 1848: 220 . Misspelling.

Spatulina Szilády 1942: 625 . Type species Spatulina engeli Szilády 1942 , by monotypy.

Diagnosis. The monophyly of Ptiolina is supported by the unique form of female tergite 9 which is rectangular and narrow, with ventrolateral arms that are easily distinguished from sternite 9.

Ptiolina species are small to moderately sized, robust flies (3.0 to 10.0 mm) that are entirely black or brown in color. Wings are hyaline or infuscate near wing veins; male holoptic, eyes separated in female; antenna with unsegmented terminal stylus, usually laterally compressed in cross section; mandibles absent; laterotergite bare; anepisternum bare; M 3 present; tibial spur formula 0:2:1; hind tibia without macrochaetae; tergite 9 with ventrolateral arms, extending posteriorly, surrounding sternite 9 laterally but largely free; female spermathecal ducts with accessory glands. Ptiolina is restricted to the Holarctic Region. Ptiolina is most readily confused with Omphalophora . It may be distinguished from this genus by having a bare anepisternum, R 4+5 anteriorly displaced from the wing tip, female tergite 7 clearly wider than long, and in the male, the gonostylus comes to a blunt point apically. For more details on the differences between Ptiolina and Omphalophora , see discussion above. Ptiolina may be immediately distinguished from Symphoromyia by having the scape approximately the same size as the pedicel, first flagellomere longer than wide (elongated anteriorly, not reniform), and bare laterotergite. Ptiolina may be distinguished from Bolbomyia by the unsegmented style, by the absence of fore tibial spurs, and by having M 3 present. Ptiolina is usually significantly larger than Spania and also differs by having a hind tibial spur.

Description. Head. Clypeus bulbous. Scape approximately same size as pedicel. First flagellomere enlarged, laterally compressed, bearing stylus of single segment. Eyes inconspicuously setulose; in female, dichoptic; in male, holoptic, not strongly flattened dorsally, ommatidia split into dorsal and ventral areas and smaller ventrally. Labella with pseudotracheae, length variable. Theca short and stout, with medial suture. Palpus one- or two-segmented. When two-segmented, distal palpomere longer than proximal segment. Stipes surrounded by membrane above theca, directed posteriorly. Lacinia present, shorter than palpus, not serrated at tip. Mandibles absent. Cibarial pump short, as long as wide or slightly longer than wide. Cornu shorter than cibarial pump. Pharyngeal pump narrow along most of length, mostly flat, approximately same length as cibarial pump.

Thorax. Mesonotum with or without vittae. Dorsocentral bristles absent; all dorsal setae of equal length. Anepisternum bare. Laterotergite bare. Proscutellum present or absent. Subscutellum not enlarged nor lengthened; inconspicuous. Wing hyaline or lightly infuscate, without markings. Costa extends to R 5, at wing tip (in P. nitida , it extends past wing tip). Lower calypter reduced. Upper calypter well developed, with broad curvature, lobe-like, width twice length or less. Humeral crossvein well developed. Sc-r crossvein weakly developed, positioned distal to h by approximate length of h. Dorsal side of R 1 setulose, ventral side bare. All other wing veins without setulae. R 1 and R 2+3 separated at wing margin. R 2+3 sinuous, apical third of R 2+3 ultimately bends anteriorly slightly, toward leading edge of wing margin. Length of R 2+3 shorter than or about same length as R 5. Base of R 4 –R 5 fork proximal or directly above distal end of cell dm. R 4 nearly straight apically or curving slightly towards anterior margin. R 5 ending anterior to or at wing tip, clearly longer than R 4+5 (r-m to R 4 origin). R-m crossvein at proximal one-fifth to near halfway of discal cell. M 3 present. M-cu crossvein present. Origin of CuA 1 at cell bm. CuA 2 greater than 1/2 length, less than 2/3 length of posterior vein of cell bm. Anal lobe well developed. Alula full, rounded with broad curvature. Cell cu p closed. Halter knob between 1/2–2/3 length of stem. Tibial spur formula 0:2:1. Hind tibial spur short. Hind coxal tubercle absent. Hind tibial macrochaetae absent (long delicate setae sometimes present). Postmetacoxal bridge absent.

Abdomen. Abdominal segments evenly tapered. In female, last 3 abdominal segments telescoped; tergite 7 much wider than long; intersegmental membrane between segments 7 and 8 especially long; sternite 8 as wide as long or wider than long. Male terminalia with epandrium simple, not containing hypandrium ventrally. Epandrium wider than long, modestly curved or strongly notched anteriorly. Tergite 10 present, undivided, narrow (clearly wider than long), setose. Hypoproct present, tomentose or setose. Cercus base held underneath epandrium, or directly adjacent to epandrium. Cerci displaced from one another, separation distance greater than three quarters width of cercus. Cerci, in posterior view cupped, forming circular outline medially. Hypandrium fused entirely to gonocoxites. Gonocoxite with sinuous dorsal ridge, leading to gonocoxal apodeme. Gonocoxal apodemes short or long enough to reach anterior margin of hypandrium. Sperm sac forming separate, distinct lobes ventrally. Lateral ejaculatory processes present, not part of sperm sac posteriorly. Ejaculatory apodeme short or moderately long, not reaching anterior margin of hypandrium. Ejaculatory apodeme rod-shaped or laterally compressed. Aedeagal tines absent. Endoaedeagal process absent or reduced. Female sternite 8 as wide as long. Female terminalia with tergite 9 entire, with narrow anteriorlydirected ventrolateral projections, mostly free, enveloping sternite 9. Spermathecae three, clubbed, sclerotized. Spermathecal ducts no more than three times length of sternite 9, not inflated at base of spermathecae. Spermathecal duct accessory glands arise at base of each spermatheca. Spermathecal ducts near junction with common duct sclerotized and somewhat thickened. Common spermathecal duct thickened; short, shorter than longest diameter of genital chamber. Genital chamber oval, moderately sized. Accessory gland posterior to genital chamber inconspicuous, easily overlooked even after staining. Accessory gland posterior to genital chamber common duct present with short paired extensions posteriorly. Sternite 9 anterior end narrowly paddle-shaped, posterior end with broad extensions posteriorly, joined together in horizontal plane centrally, held in vertical plane laterally. Tergite 10 entire; short, length less than half width. Sternite 10 sclerotization weakened centrally, making it appear as if sclerite divided into two lateral components. Sternite 10 roughly pentagonal, pointed posteriorly (very broad, wider than long; nearly rectangular). Cercus twosegmented. First segment of cercus not elongate, without ventral process. Ventral lobes of first segment of cercus not curving ventrally towards one another to form ring. Basal cercal segment separated from one another dorsally by approximate width of second cercal segment. Second cercal segment narrow, elongated (~3x longer than wide or more), with apical sensory pits.

Larva. Body with 11 segments. Thoracic segments with creeping welts ventrally. Head capsule not folded within second segment. Head capsule composed of a single, undivided plate (dorsal plate). Head capsule less than 4.5 times longer than greatest width (1.5 width/5.0 length). Mandibular brush absent (or very reduced). Mandibular hook without groove or canal, smooth, without microsetae. Labral teeth very well developed, heavily sclerotized, in two rows, converging anteriorly. Maxilla sclerotized (strongly toothed, with three teeth). Saw sclerite of mandibular base absent. Maxillary palpus soft, segments poorly differentiated, threesegmented. Antenna apparently one-segmented, dome-shaped, short. Unpaired salivary pump absent. Posterior tentorial expansion fused to each other posteriorly, with thin extension produced anteriorly.

Biology. Ptiolina larvae are slow moving, “shining green in life,” and feed on mosses, according to Brindle (1959). Others have also noted an association of Ptiolina and moss ( Brauer 1883; Lane & Anderson 1982). Ptiolina obscura Fallén (= P. nigrina Wahlberg ), however, apparently feeds on the liverwort species Marchantia polymorpha ( Nartshuk 1995) . Ptiolina larvae have weakened and reduced mouthparts, a condition that is appears wholly unsuitable for predation.

Literature. Hardy & McGuire (1947) provide a key to North American species. Narchuk (1969) gives a key to eastern European species.

Notes. In the Palearctic catalogue ( Majer 1988), Ptiolina obscura Fallén is given as the type species for the genus Ptiolina , by original designation. However, Zetterstedt (1842) placed two species in the new genus Ptiolina , without designating the type species. Frauenfeld (1867) designated the type species as Ptiolina obscura (Fallén) (1867: 467, in key), which was originally described as Leptis obscura Fallén.