28.017 Batia lambdella (Tawny Crescent)
ws:13-18mm; Jun-Jul; gorse (Ulex spp); common on heath, scrub and open woodland in S.England and Wales, also EC Scotland
ID: The 3 Batia species have a similar pattern. B.lambdella is the largest with little if any size overlap (B.lunaris 9-11mm, B.internella 9-13mm). The pattern of the black tornal lambda mark differs in detail between the species: in B.lunaris the costal portion is reduced abruptly to a narrow line, in B.lambdella it tapers gradually to a rounded end and in B.internella it tapers gradually to a point. See Batia for more info.
Female genitalia: (based on the drawings in MBGBI4.1 p57) - All three species have a rounded, somewhat spiculate, signum in the bursa copulatrix (BC) and a series of small spicules at the posterior end of the ductus bursae (DB). Differences occur in the shape of the periosteal plate (S8 ventral plate) and in the DB-CB junction. In B.lambdella the posterior margin of the ventral S8 plate is fairly straight, the anterior margin has rounded projection on each side of a medial emargination and the ostium is in the posterior half of the plate; in B.lunaris the posterior margin is deeply emarginate, the anterior margin has small projections on each end of a fairly straight edge and the ostium opens in the anterior half of the plate; in B.internella the posterior margin is shallowly emarginate, the anterior margin is straight and the ostium opens more or less in the centre of the plate. In B.lunaris the DB is just under half the diameter of the CB; in both B.lambdella and B.internella the DB is much narrower than the CB (~1/5); in both B.lunaris and B.internella the DB joins the CB at its posterior pole but in B.lambdella the junction is near the anterior end of the CB so that the CB is somewhat recurved on the DB.
Female genitalia: (based on the drawings in MBGBI4.1 p57) - All three species have a rounded, somewhat spiculate, signum in the bursa copulatrix (BC) and a series of small spicules at the posterior end of the ductus bursae (DB). Differences occur in the shape of the periosteal plate (S8 ventral plate) and in the DB-CB junction. In B.lambdella the posterior margin of the ventral S8 plate is fairly straight, the anterior margin has rounded projection on each side of a medial emargination and the ostium is in the posterior half of the plate; in B.lunaris the posterior margin is deeply emarginate, the anterior margin has small projections on each end of a fairly straight edge and the ostium opens in the anterior half of the plate; in B.internella the posterior margin is shallowly emarginate, the anterior margin is straight and the ostium opens more or less in the centre of the plate. In B.lunaris the DB is just under half the diameter of the CB; in both B.lambdella and B.internella the DB is much narrower than the CB (~1/5); in both B.lunaris and B.internella the DB joins the CB at its posterior pole but in B.lambdella the junction is near the anterior end of the CB so that the CB is somewhat recurved on the DB.
§1 Sychnant Pass, Gwynedd; 21/07/2015; female; fw 7.9mm; to light
§2 Dungeness, Kent; 13/07/2018; male; fw 6.5mm; to light
§3 Mortehoe, Devon; 10/07/2020; male; fw 6.8mm
§4 New Forest, Hampshire; 05/08/2024; female; fw 6.9mm
All images © Chris Lewis
§2 Dungeness, Kent; 13/07/2018; male; fw 6.5mm; to light
§3 Mortehoe, Devon; 10/07/2020; male; fw 6.8mm
§4 New Forest, Hampshire; 05/08/2024; female; fw 6.9mm
All images © Chris Lewis
Page published 03/08/2015 (§1) | §2 added 16/09/2018 | §3 added 28/01/2021 | §4 added 15/10/2024