Pseudomicracis pennata

Pseudomicracis pennata (Schedl, 1965)

(Figs 38, 41, 44, 47, 50, 53)

Micracis pennatus Schedl, 1965: 63, orig. spelling

Pseudomicracis pennatus (Schedl, 1965), combination by Wood (1984)

Type material. Holotype, male: Madagascar, Sandrangato [likely south of Moramanga] [MNHN]. Allotype, male: same data as holotype [NHMW].

Diagnosis. Length 1.8–2.2 mm, 2.2 × as long as wide. Male declivity on interstriae 4–5 with a tall, narrow ridge, extending the total length of elytra by one-quarter; interstrial setae short, spatulate or truncated, densely placed, strongly confused. Female with rounded declivity, interstrial setae conical, in part confused on declivity

Distribution and biology. Madagascar. Biology not known.

Remarks. Gender of genus is feminine (Alonso-Zarazaga & Lyal 2009) and the species epithet is modified accordingly.

Sexual dimorphism in Pseudomicracis and other Micracidini

Almost all Micracidini species have some sort of sexual dimorphism in the head where females often have longer setae on a larger antennal scapus, and a variously modified frons that may be concave and textured, or flattened to lightly bulbous and shiny, with or without dense setae. It is presumed that this is due to females being the second arriving sex to a tunnel system, and that the male will control access (Kirkendall et al. 2015). Females have been observed to court males in the tunnel opening and apparently the tactile stimuli provided by the fluffy antennal and frontal apparatus is important for male acceptance. Typically a male will accept exactly two females to their tunnel entrance, although this is an average condition with many exceptions given the resource availability on site.

Pseudomicracis is special among the Micracidini in that males often differ from the females not only in head structures, but also in the shape of the pronotum and the declivity. Some species have males with a distinct row of teeth along the anterior margin of the pronotum, a trait which occasionally appear in other micracidine taxa (Jordal 2021c). Almost all Pseudomicracis have males with lightly to quite strongly granulated declivity and posterior elytral disc. Additionally, the interstrial setae are broader and truncated, compared to the narrowly spatulate setae in females. The most exceptional features are seen in species in the Saurotocis group which have males with huge tubercles along the outer lateral part of the declivity and the overall elytral vestiture is dense and confused. Molecular analyses (Fig. 1) nevertheless show that these features are derived within the typical Pseudomicracis lineage, which is also supported by female morphology in these species which is typical for the genus (Figs 45–53). The male inclination for declivital evolution is also seen in the peculiar P. coronatus sp. nov. which also has males with a granulated demarcation of the declivity. It is not clear what the purpose of rough declivities might be for the males, but similar traits are found throughout the subfamily and may even appear in females (Kirkendall et al. 2015).