Leaus Matthews & Lawrence, 1992

Matthews, Eric G. & Lawrence, John F., 2015, Trachelostenini sensu novo: redescriptions of Trachelostenus Solier, Myrmecodema Gebien and Leaus Matthews & Lawrence, based on adults and larvae, and descriptions of three new species of Leaus (Coleoptera: Tenebrionidae), Zootaxa 4020 (2), pp. 289-312 : 301-304

Leaus Matthews & Lawrence, 1992

( Figs 5 , 10 , 20–36 , 39, 40 , 44, 47, 48 , 50, 51, 54, 56 )

Type species. Leaus tasmanicus Matthews & Lawrence, 1992 , by monotypy.

Redescription. Adults. With the characteristics of the tribe. Length 3.9–8.4 mm. Body parallel-sided, 2.2–3.0 times as long as wide. Upper surfaces nitid fuscous or castaneous, clothed with recumbent white setae forming patterns on dark background, also with long sparse erect pilosity. Head: Basal membrane of labrum narrow but exposed and complete. Eyes entire, broadly oval. Antennae short, not quite reaching base of prothorax, antennomeres obconic, gradually widening distally, apical segment large and suboval. Mentum small, subquadrate or a little transverse. Prothorax: Pronotum densely punctate, moderately convex, lateral carinae present. Procoxal cavities internally open. Trochantins absent. Pterothorax: Elytral disc at least slightly uneven, without striae, with partly effaced puncture rows. Wings fully developed. Legs: Procoxae subconical, approximated, projecting well below prosternum. Tarsi about as long as tibiae. Abdomen: Intercoxal process narrowly triangular. First three ventrites connate. Defensive glands present, small, widely separated. Female: Ovipositor with paraprocts elongate, about twice as long as coxites, baculi of first coxite lobes diagonal, short, coxites with four distinct pairs of lobes.

Spermatheca coiled, attached to base of accessory gland. Single vaginal sclerite with median keel and transverse lateral wings.

Description. Larva. With the characteristics of the tribe. Dorsal surfaces bicolored with a complex pattern of dark brown markings on a yellow background. Head with sides subparallel ( Fig. 40 ); larger anterior epipharyngeal sensilla ( Fig. 54 ) with anterior 2 moderately widely separated and well separated from the posterior 4, which form a subquadrate cluster; posterior sensilla forming two longitudinal rows of 4; mandibles bidentate with short subapical tooth on incisor edge; left mola with several weak transverse ridges; gula 3 times as long as wide; hypopharyngeal sclerome anteriorly trilobed. Prothorax almost as long as wide. Legs slightly longer than thoracic width and clothed with fine hairs. Abdomen about 3.5 times as long as thorax; tergum I with weak anterior carina; tergum IX ( Fig. 47 ) slightly shorter at midline and slightly narrower than VIII, carina simple; urogomphi ( Fig. 48 ) each with 4 setiferous tubercles at about middle; surface of concave disc lightly pigmented, dark-rimmed pits less regularly spaced and concentrated around a pair of posterolateral impressions; segment X with a pair of tubular pygopods ( Fig. 44 ). Spiracles annular-cribriform with the peritreme completely surrounded by a cribriform plate ( Fig. 56 ).

Larval material examined: Leaus tasmanicus Matthews & Lawrence. AUS: Tasmania: Pelion (41.50S, 146.08E), 1991, pyrethrin knockdown, rainforest, P. Greenslade & M. Comfort ( ANIC).

Discussion. At the time of its description Leaus was placed in Heleini because it shows the basal tenebrionine characteristics of that tribe and, in particular, similarities to the heleine genus Lepispilus . Both Leaus and Lepispilus have pale dorsal setae which form a mottled pattern, and they share the unusual character of a vaginal sclerite. At the same time, it was mentioned that there is a resemblance between Leaus and Trachelostenus in the form of prominent coxae. Later, Matthews (2003) transferred Leaus to Titaenini, another basal tribe of Tenebrioninae , as discussed in the introduction. We now know that Titaenini as then conceived by Matthews was a paraphyletic assemblage of primitive Tenebrioninae sharing mainly plesiomorphies.

Lepispilus differs from Leaus in the absence of prominent coxae, presence of a medial fleck on the wings, complete elytral epipleura, aedeagal alae not of the appendiculate type, and unique ovipositor structure. The ovipositor of Lepispilus (illustrated in Matthews & Bouchard 2008, fig. 47C) does not resemble that of any other known tenebrionid. There is therefore no evidence of a direct relationship between Lepispilus and Leaus or any other trachelostenine.

The peculiar type of spiracular opening surrounded by a cribriform plate in larvae of Leaus (called annularcribriform by Lawrence et al. 2011) is perhaps an adaptation to wetter habitats and has been found sporadically in various other unrelated families of Coleoptera including Trogossitidae-Lophocaterinae, Mycteridae-Hemipeplinae, and Chrysomelidae-Cryptocephalinae.

Figures

FIGURES 3 – 5. Aedeagi: 3, Trachelostenus inaequalis with penis extracted; 4, Myrmecodema michelbacheri; 5, Leaus monteithi. a—ala of paramere. Scale bars 1 mm.

FIGURES 8 – 10. Inside of abdominal ventrites. 8, Trachelostenus inaequalis; 9, Myrmecodema michelbacheri; 10, Leaus tropicalis. Scale bars 1 mm.

FIGURES 20 – 23. Leaus vaginal sclerites (vs): 20, L. tropicalis, sclerite in situ; 21, L. tasmanicus; 22, L. monteithi; 23, L. sp.

FIGURES 24 – 26. Leaus ovipositors: 24, L. tropicalis; 25, L. monteithi; 26, L. sp. cb—baculus of coxite 1; pb—baculus of paraproct. Scale bars 1 mm.

FIGURES 27 – 32. Leaus habitus, dorsal except 29: 27, L. tasmanicus paratype ♀ (SAMA); 28, L. tropicalis holotype ♀ (QMBA); 29, L. tropicalis paratype ♂ (ANIC); 30, L. monteithi holotype ♀ (QMBA); 31, L. elusus holotype ♂ (QMBA); 32, L. sp. ♀ (ANIC). Scale bars 1 mm.

FIGURES 33 – 36. Leaus habitus, lateral: 33, L. tasmanicus holotype ♂ (SAMA); 34, L. monteithi sex not determined, paratype (QMBA); 35, L. tropicalis holotype ♀ (QMBA); 36, L. elusus holotype ♂ (QMBA). Scale bars 1 mm.

FIGURES 37 – 41. Trachelostenine larvae: 37 – 39, head and prothorax, dorsal; 37, Myrmecodema nycterinoides; 38, Trachelostenus inaequalis; 39, Leaus tasmanicus; 40, L. tasmanicus, larval head, dorsal; 41, T. inaequalis, larval head, lateral.

FIGURES 42 – 48. Trachelostenine larvae: 42 – 44: abdominal apex, lateral: 42, Trachelostenus inaequalis; 43, Myrmecodema nycterinoides, 44, Leaus tasmanicus; 45 – 48: abdominal apex, dorsal: 45, Trachelostenus inaequalis; 46, Myrmecodema nycterinoides; 47 – 48, Leaus tasmanicus.

FIGURES 49 – 56. Trachelostenine larvae: 49, Trachelostenus inaequalis, ventral mouthparts and hypopharynx, dorsal. 50 – 51, Leaus tasmanicus, mandibles: 50, right, dorsal; 51, left, dorsal. 52 – 54: labrum-epipharynx, ventral: 52, Trachelostenus inaequalis, 53, Myrmecodema nycterinoides, 54, Leaus tasmanicus. 55 – 56, abdominal spiracle: 55, Myrmecodema nycterinoides. 56, Leaus tasmanicus.