Tvetenia verralli

Author: (Edwards, 1929)

Exuviae 3.2-4.5mm long (m=3.6mm, n=7).
Cephalothorax: Thoracic horn 435-575µm long (m=494µm, n=7), broadest at base, tapered to apex, more strongly tapered over the basal half (053l.jpg); length base 0.23-0.33x length horn (m=0.27, n=7); ThR (base) 1.4-2.2 (m=1.8, n=7). Thorax wrinkled near suture. Pearl row consisting of a single row of tubercles.
Abdomen: Hook rows on tergites broken medially (053m.jpg), hooks III 3/4-6/7, IV 3/3-5/7, V 2/3-4/6 (n=7). Tergite I without points on the posterior humps. Segments II-V dorsally nearly covered with small points except for the adhesion marks; VI-VIII progressively less extensively armed (no anterior transverse band of strong points). Posterior point bands on tergites II-VII broken medially but the gap armed with scattered points. Sternites with the transverse toothed bands continuous medially. Segment VIII with all lateral setae very thin, short, inconspicuous.
Anal segment: Anal lobes without fringe. Anal macrosetae conspicuous, with an additional fourth seta internally, well-separated from the other three (053n.jpg).
(Linked adult male: Langton and Pinder, 2003a)

Species keys out at Page 712: Orthocladiinae 124 Tvetenia of the Text Key.

Holarctic species: widespread in Europe, circum-Mediterranean.
(For more information see module IdentifyIt – file: Orthocladiinae).

Ecological notes