Mouthpart sensilla of cave species of australian paratemnopteryx cockroaches (BLATTARIA : BLATTELLIDAE)

Abstract

The external morphology and distribution of sensilla on maxillary and labial palpi are described for 3 Australian cave-dwelling cockroach species, Paratemnopteryx stonei, P. howarthi, and P. sp. nov (Blattaria : Blattellidae), using scanning electron microscopy. The apex of the maxillary palpus expands ventrally into a flexible pad with a distinct sensillar field. The total number of sensilla ranges from 1045 (males)–1486 (females). Sensillar fields of females are larger and contain more sensilla than those of the males, although the density of sensilla is usually equal or greater for males. Papilla-like groove-and-slit chemoreceptors comprise 93–97% of the sensilla. Two types of trichoid sensilla occur along with bifurcuted sensilla and rare basiconic sensilla that are poreless and have an inflexible socket. Chaetic sensilla occur on all species and several thousand pectinate scales, with bulbous bases, and spicules are present in large fields on each side of the sensillar field. The apex of the labial palpus is only slightly expanded into a sensillar field. Sensillar diversity is similar to the maxillary palpus but there are only 5–29% as many sensilla, the number ranging from 97 (males)–346 (females). Sensillar fields of females are slightly to much larger than those of males but the sensillar density is equal between the sexes or greater on males. Two types of trichoid and one or two types of basiconic sensilla occur on each species. Chaetic chemoreceptors are present along with three types of non-socket spines. Sensilla varied moderately in morphology and gender-related abundance from those on epigean cockroach species.