Pavlostysia, Popov, 2008

Popov, Yuri A., 2008, Pavlostysia wunderlichi gen. nov. and sp. nov., the first fossil spider-web bug (Hemiptera: Heteroptera: Cimicomorpha: Plokiophilidae) from the Baltic Eocene amber, Acta Entomologica Musei Nationalis Pragae 48 (2), pp. 497-502 : 498-499

Pavlostysia gen. nov.

Type species. Pavlostysia wunderlichi sp. nov.

Description. Small species, slender, not longer than 1.5 mm. Surface mat and bare, only preocular part of head and anterior part of costal margin of hemelytra bearing setae and trichobothria; setae on anterior angle of pronotum absent; general coloration uniformly dark, hemelytra without whitish spots.

Head strongly elongate, more than 1.5 times as long as wide; preocular and postocular parts of an equal length; eyes strongly flattened and weakly developed ocelli (male); tylus (anteclypeus) long, narrow, subparallel, narrowed towards apex and greatly surpassing small jugae; postocular part of head very long, lateral margins parallel, not separately rounded. Antennae relatively short, 0.5 times as long as body length; antennal segments 1 and 2 moderately thin, stick-shaped, segments 3 and 4 somewhat thinner; segment 1 attaining apex of head. Rostrum very long, slender and surpassing hind coxae; segment 1 short and broad, ratio of lengths of segments 1-4 equal to 5: 10: 10: 12.

Pronotum trapezoidal, weakly transverse, less than 1.5 as wide as long; collar broad, posterior margin deeply emarginated, posterolateral angles broadly rounded, calli inconspicuous, placed near lateral margins of anterior part of pronotum. Mesoscutum glabrous and of equal length as scutellum. Hemelytra uniformly dark, with weakly expressed two veins (?R+M and Cu); ‘corial glands’ visible as punctation of exocorium; costal fracture distinct and long, located about one-fourth distance from base to apex of corium; coriomembranal juncture feebly marked, cuneus weakly distinct; membrane without venation. Legs (especially femora) slender, very long and thin, unarmed; tarsi long, 3-segmented, pretarsus consisting of two simple, short, very slender claws of conspicuously unequal length, without other discernible structures.

Abdomen rather narrow, slender, flattened laterally, ventrolateral tergites fused with sterna; pygophore short, very broadly connected to abdomen, opening of pygophore directed dorsally and parameres lying dorsally.

Differential diagnosis. Pavlostysia gen. nov. is clearly a member of the Plokiophilidae , primarily by the structure of the head, pronotum, and hemelytra (especially ‘corial glands’ – the most distinctive autapomorphy of the Plokiophilinae ), long legs and elongate, asymmetrically developed claws. The new genus is similar to the extant Neotropical genus Lipocophila and the features common to both genera are as follows: strongly elongate (especially the postocular part) head, broad pronotal collar, strongly emarginated posterior margin of pronotum, very long and slender legs (especially femora), three-segmented tarsi (this is probably a symplesiomorphy), long, slender and nearly straight claws of unequal length, etc. On the other hand, Pavlostysia gen. nov. differs distinctly from Lipocophila by the following features: uniform dark coloration, strongly flattened eyes and weakly visible ocelli, shorter antennae, which are half as long as body length (species of Plokiophiloides and Heissophila macrotheleae have the same proportions), longer rostrum surpassing hind coxae, corium-membrane boundary obscure, cuneus weakly distinct, and membrane without venation and absent corial process. Except Pavlostysia gen. nov. and Lipocophila, only Heissophila possesses three-segmented tarsi, which set them apart from all other plokiophilid genera ( SCHUH 2006). Moreover, the anterolateral angles of pronotum lack setae in Pavlostysia gen. nov. and in Heissophila . However, the distinctly shorter head and widely distributed corial glands, including pronotum, hemelytra and antennal segments, easily distinguish Heissophila from the two genera mentioned above; in Heissophila the hemelytral membrane also has four distinct longitudinal veins as in some Anthocoridae ( SCHUH 2006) . Finally, the genital segment in all known Plokiophilidae except Heissophila is elongate and tubular.

Etymology. This new genus is named after my old good friend and colleague, Prof. Pavel Štys, an outstanding specialist on the Heteroptera , on the occasion of his 75th birthday. The spelling of Pavlostysia gen nov. is inspired by Czech and Russian declension of ‘Pavel’; feminine.

Bionomics. Pavlostysia gen. nov. most probably lived in spider webs. Arachnophilous heteropterans prefer webs with thick, horizontal mats or funnels. SCHUH (2006) listed the known associations of Plokiophilidae with webs built by relatively large spiders, e.g. Agelena C. L. Koch, 1837 , and Tengella Dahl, 1901 (Araneomorphae: Agelenidae ), or Ischnothele Ausserer, 1875 (Megalomorphae: Dipluridae ) and Macrothele Ausserer, 1871 (Megalomorphae: Hexathelidae ).