Stenomastigus longicornis

Jałoszyński, Paweł & Kilian, Aleksandra, 2016, Description of the second- and third-instar larva of South African Stenomastigus longicornis (Boheman) (Coleoptera: Staphylinidae, Scydmaeninae), Zootaxa 4158 (2), pp. 151-182 : 153

Description of Stenomastigus longicornis larva

Larvae of both studied instars campodeiform, strongly elongate and slightly flattened, with nearly parallel-sided thorax and distinctly narrowing abdomen; their antennae and legs strikingly long ( Figs 1–4, 6–7). Living larvae ( Figs 1–4) extensively use their pygopod (i.e., abdominal segment X) in locomotion, so it is strongly bent ventrally most of the time; antennae typically hold with first antennomere raised and distal portion of antenna bent anteroventrally to examine ground and objects in front of larva. Orientation of pygopod and antennae usually wellpreserved post mortem ( Fig. 7). Second instar ( Figs 1–4) has head, thorax and abdomen orange, whereas antennae, maxillary palps and legs light brown; third instar creamy white with dark brown head, tergal and sternal plates, scape, distal portions of femora and proximal portions of tibiae ( Fig. 7); stemmata in both instars nearly black. Colors of larvae stored for several weeks in ethanol strongly fade ( Fig. 6). Body in both instars sparsely covered with long setae, mostly unmodified, with pointed apices; some setae have truncated and slightly bifid apices. Two types of strongly modified setae were found in both instars. Long setae with surface covered with irregular protuberances located around frontal impression ( Figs 19–21). Very short, flat, leaf-like setae with fine elongate ribs distributed along anterior and posterior margins of tergal plates ( Figs 51–57), often partly covered by folds of intersegmental membranes ( Figs 52, 55) and poorly visible. Dense, hair-like microtrichia cover posterior margins of antennal sockets ( Fig. 22); sparse and thorn-like microtrichia located on distal section of antennomere II ( Fig. 26); external surface of all coxae and some abdominal tergal and sternal plates covered with sparse scale-like or thorn-like asperities ( Figs 38, 62–64); thoracic tergal plates densely covered with small and rounded tubercles ( Figs 47–50, 51–53) forming pattern composed of smooth areas within regions of asperity ( Figs 47–48, 51–52); intersegmental membranes densely covered with round tubercles and scale-like or thorn-like asperities ( Figs 37, 50, 60, 65–66). Insertions of long setae on tergal and sternal plates surrounded by cuticle devoid of asperities but covered with wrinkles directed toward seta ( Fig. 49).