 Pergamon Int[ J[ Insect Morphol[ + Embryol[\ Vol[ 16\ No[ 3\ pp[ 180Ð299\ 0887 Þ 0887 Elsevier Science Ltd[ All rights reserved Printed in Great Britain 9919!6211:87 ,08[99¦9[99 PII ] S9919Ð6211"87#99910ÐX MOUTHPART SENSILLA OF CAVE SPECIES OF AUSTRALIAN PARATEMNOPTERYX COCKROACHES "BLATTARIA ] BLATTELLIDAE# Roger G[ Bland\$ David P[ Slaney% and Philip Weinstein& $ Department of Biology\ Central Michigan University\ Mt Pleasant\ MI 37748 U[S[A[ ^ % Department of Zoology\ James Cook University\ Townsville\ Queensland 3700\ Australia ^ & Department of Public Health\ Wellington School of Medicine "University of Otago#\ P[O[ Box 6232\ Wellington South\ New Zealand "Received April 29\ 0887 ^ accepted June 7\ 0887# Abstract*The external morphology and distribution of sensilla on maxillary and labial palpi are described for 2 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 ~exible pad with a distinct sensillar _eld[ The total number of sensilla ranges from 0934 "males#Ð0375 "females#[ Sensillar _elds 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 82Ð86) of the sensilla[ Two types of trichoid sensilla occur along with bifurcuted sensilla and rare basiconic sensilla that are poreless and have an in~exible socket[ Chaetic sensilla occur on all species and several thousand pectinate scales\ with bulbous bases\ and spicules are present in large _elds on each side of the sensillar _eld[ The apex of the labial palpus is only slightly expanded into a sensillar _eld[ Sensillar diversity is similar to the maxillary palpus but there are only 4Ð18) as many sensilla\ the number ranging from 86 "males#Ð235 "females#[ Sensillar _elds 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[ Þ 0887 Elsevier Science Ltd[ All rights reserved[ Index descriptors "in addition to those in the title#] chemoreceptors\ morphology\ maxillary palpus\ labial palpus\ insects[ INTRODUCTION Tropical cave!dwelling "hypogean# insects\ including Australian species\ have been found in greater diversity than anticipated in recent years "cf Bland et al[\ 0887#[ The development of tropical hypogean populations has often been referred to as an adaptive shift from surface "epigean# living rather than a relictual process "Chapman\ 0871\ 0875 ^ Howarth\ 0876\ 0880#[ Various degrees of troglomorphic adaptations occur\ presumably including sensory modi_cation on mouthparts and antennae[ Mouthpart sensilla are primarily contact chemoreceptors used to test food palatability and determine the chemical characteristics of a substrate[ A few chemoreceptors are olfactory and others are mechanoreceptive\ the latter used to analyze the architecture of the surrounding sub! strate\ to self!groom\ and to perform other activities "Zacharuk\ 0874#[ Olfactory receptors may reasonably be expected to proliferate in the cave environment because of the lack of visual cues\ whereas hygro!and thermo! receptors "Altner et al[\ 0872# may be absent in the stable environment[ The purpose of this study is to describe the external morphology and distribution of sensilla on the apices of the maxillary and labial palpi of three Australian cave!  Corresponding author ] Tel[ ] 99 406 663 2344 ^ e!mail ] roger[g[ blandÝcmich[edu 180 dwelling cockroach species\ Paratemnopteryx stonei Roth\ P[ sp[ nov[\ and P[ howarthi Roth from North Queensland[ This research complements a similar study on the antennal sensilla of the same species "Bland et al[\ 0887#[ Paratemnopteryx stonei has developed eyes\ brachypterous tegmina and vestigial hindwings\ and brown pigmentation[ Paratemnopteryx sp[ nov[ is similar but sexually dimorphic ^ males generally are macrop! terous "Slaney and Weinstein\ 0885#[ Paratemnopteryx howarthi may have well!developed eyes and be macrop! terous\ or have reduced eye!development and a brachyp! terous condition[ We collected specimens from di}erent cave systems for inter!cave comparisons and to compare with epigean species[ This is the _rst study to compare chemosensilla of male and female cockroaches[ MATERIALS AND METHODS The specimens used were identical to those in an earlier study on antennae "Bland et al[\ 0887#[ Brie~y\ brachypterous P[ stonei was obtained from Barker|s "Race C# and Bayliss "Race B# caves "Roth\ 0889#\ lava tubes in the Undara system ^ brachypterous female and macropterous male P[ sp[ nov[ were collected from Rope Ladder cave\ a limestone cave of the Fanning River karst region ^ and macropterous P[ howarthi was obtained from Kiwi cave\ a limestone cave in the Chillagoe Caves National Park\ and Nasty cave\ a large tube in the Undara system "Matthews\ 0874#[ Mouthparts were obtained from each of 1 males and females from each cave[ Fixation of maxillary and labial palpi by immersion of freshly excised apical segments into bu}ered glutaraldehyde resulted in a col!