First description of the larva of Dinaraea Thomson, 1858, with comments on chaetotaxy, pupa, and life history based on two saproxylic species from Europe (Staphylinidae, Aleocharinae, Athetini)

Abstract

The paper describes the morphological ultrastructure of the previously unknown early (L1) and late larval instars (L2–3) of Dinaraea, including chaetotaxy, pupal cocoon, prepupa, and pupa, based on the saproxylic species D. aequata Erichson and D. linearis Gravenhorst. Diagnostic larval characters for the genus Dinaraea are given for the first time. Morphological differences between mature larvae of these two species relate to the colouration and degree of flattening of the body, details of antennal structure, anterior margin of the labrum, mandibles, and mala. The differences are relatively small, probably because of the similar ecological preferences of both species. As in the case of other aleocharine larvae, L1 in Dinaraea differs from L2–3 in the lack of some setae on the dorsal surface of the head and thorax, and on the abdominal tergites and sternites; the presence of a subapical seta on the urogomphi; egg bursters on some thoracic and abdominal tergites; a darker antennal segment III; and the relatively longer urogomphi and their apical setae. The differences established in the features of the chaetotaxy of L1 and L2–3 between Athetini (Dinaraea), Oxypodini (Thiasophila) and Homalotini (Gyrophaena) correspond with the molecular marker-based relationships of these taxa.

Comparative larval ultramorphology of some myrmecophilous Aleocharinae (Coleoptera, Staphylinidae), with a first description of the larvae of Amidobia talpa (Heer O, 1841) and Oxypoda haemorrhoa (Mannerheim C.G., 1830), associated with the Formica rufa species group

“…Measurements (Table 1) were made on freshly killed specimens. The terms of morphological structures, chaetotaxy (selected aspects only) and their abbreviations generally follow Ashe and Watrous (1984) and Staniec et al (2018), with modifications in some of the figures. The material examined for the measurements is listed in Table 1.…”

“…The combination of characteristics distinguishing mature larvae of Amidobia and Oxypoda from known larvae of other genera within the subfamily Aleocharinae are as follows (Paulian 1941, Pototskaya 1967, Topp 1975, Ashe 1981, Ashe and Watrous 1984, Ashe 1985, Ahn 1997, Jeon and Ahn 2009, Staniec et al 2009, 2010, 2016, 2018, Zagaja et al 2014, the present study): Amidobia – (1) body extremely slim; (2) head wider (1.1 ×) than pronotum; (3) sensory appendage of antennal segment II longer (1.1 ×) than antennal article III; (4) labrum rectangular; (5) anterior margin of labrum shallowly excised in the centre; (6) seta Ld2 of labium spiniform; (7) epipharynx with about 20 long cuticular processes and 2 pores centrally; (8) mandible stocky with 2 preapical teeth; (9) mala wide, distinctly dilated anteriorly; (10) adoral margin of mala with 10–12 teeth (4–5 small distally); (11) dorsal side of mala with about 25 cuticular processes; (12) ligula dome-like, as long as wide; (13) spiracle with unique perforation; Oxypoda – (1) head sides weakly rounded; (2) labrum semi-circular; (3) seta Ld2 of labium very short, verrucous; (4) epipharynx with about 100–150 short cuticular processes and 10 centrally; (5) mandible slender with 1 preapical tooth; (6) interior edge of apical and preapical tooth serrate; (7) adoral margin of mala with 11–15 teeth including 1 biggest proximally and a few small distally; (8) mala slender, narrowed anteriorly; (9) dorsal side of mala with about 15 cuticular processes; (10) ligula finger-like, almost twice as long as wide.…”

“…They mainly involve the structural details of the mouthparts, and in the case of the former taxon, of the antennae and spiracles as well. These features were established with reference to well-known larvae of other aleocharine species of diverse ecological preferences (Ashe and Watrous 1984, Staniec et al 2009, 2010, 2017, 2018, Zagaja et al 2014), among which anthill symbionts, represented by the two titular staphylinids, are deserving of particular scrutiny.…”

“…Relationships between myrmecophiles and their hosts exhibit varying degrees of advancement (Wasmann 1894, Hölldobler 1971, Hölldobler and Wilson 1990, Stoeffler et al 2011, Staniec et al 2017, Zagaja et al 2017), which may be correlated with certain morphological adaptations in actively living developmental forms, including larvae. The data listed in Table 2 summarize the current state of our studies, which focus on the external structure of the larval stages of European myrmecophilous aleocharine species, especially in relation to the differing degrees of integration with their hosts (Stoeffler et al 2011, Staniec et al 2009, 2017, 2018, Zagaja et al 2014). Five of the six species (genera) are known ant symbionts, associated with two species of these hymenopterans.…”

The oldest case of paedomorphosis in rove beetles and description of a new genus of Paederinae from Cretaceous amber (Coleoptera: Staphylinidae)

“…nov. At the same time, the vast majority of Staphylinidae larvae have Y-shaped ecdysial sutures (e.g. Figures 12, 13 in Staniec et al 31 ; Figs. 15, 24 in Grebennikov & Newton 32 ; Figs.…”