Scanning the Hyocephalidae: details of their external morphology with respect to phylogenetic relationships within Eutrichophora (Hemiptera: Heteroptera)
Kment Petr, Hemala Vladimír, Malenovský Igor
Acta Entomologica Musei Nationalis Pragae 59(2): 423-441, 2019
Published online: 15th August 2019
Published in print: 31st December 2019
Views: 1525
Abstract: Hyocephalidae (Hemiptera: Heteroptera: Pentatomomorpha) is a small family of
true bugs containing two genera and three species endemic to Australia. For the
first time, we examine here selected structures of their external morphology
using scanning electron microscopy – the external structures associated with
the metathoracic and dorsoabdominal scent glands, the strainer organ on the
sternite III, as well as the trichobothrial pattern and ultrastructure. The
following character states are confirmed (i, ii, iii) or newly recognised (iv,
v) as autapomorphies of Hyocephalidae: i) apically projected scimitar-shaped
peritreme of the metathoracic scent glands; i) presence of a strainer organ on
sternite III in both sexes; iii) trichobothria on sternite V placed immediately
ventrad of spiracle, iv) trichobothria on each of abdominal segments III–VII
all grouped together within a common trichome, and v) presence of crocus-like
structures within the trichome. Of particular interest is the presence of a
shallow open bothrium (type B) surrounded by a trichome in Hyocephalidae, a
probably derived character state shared with Pyrrhocoroidea and most Lygaeoidea,
while Stenocephalidae (previously considered to be closely related to
Hyocephalidae and used here for comparison) and the remaining Coreoidea possess
a recessed bothrium of type A2, lacking the trichome. The morphology of
trichobothria in Hyocephalidae may thus suggest either their closer relationship
to Lygaeoidea + Pyrrhocoroidea than to Coreoidea, or a parallel evolution of the
open bothrium with trichome in Eutrichophora. We highlight the importance of
Hyocephalidae for a better understanding of the phylogeny of Eutrichophora and
the urgent need to obtain phylogenomic data for future research. A taxonomic
catalogue of Hyocephalidae is supplemented. The neotype designation for
Hyocephalus aprugnus Bergroth, 1906 made by Štys (1964) and supported by Grant
& Štys (1970) is found invalid.
Key words: Hemiptera, Heteroptera, Trichophora, Coreoidea, Lygaeoidea, Pyrrhocoroidea,
Hyocephalidae, Stenocephalidae, morphology, scent glands, strainer organ, trichobothria, ultrastructure, phylogeny, catalogue, invalid neotype designation