Records of the Western Australian Museum 18: 323-328 (1997). 
Sellnickiella ( Sellnickiella) biunguiculata sp. nov.: a noteworthy species of 
Labidostomatidae from Australia (Acari: Actinedida: Labidostomatina) 
Michel Bertrand 
Laboratoire de Zoogeographie, University Montpellier 3, 
route de Mende, F-34199 Montpellier Cedex5, France 
Abstract - Sellnickiella (S.) biunguiculata sp. nov. is described from Australia. 
This species shows an exceptional apomorphic character among 
Labidostomatidae: the lack of median unguis on legs II—IV. Otherwise, this 
species is a typical member of Sellnickiella (Sellnickiella), a gondwanan group 
which representatives recorded from South America, South Africa, Australia 
and New Zealand. 
INTRODUCTION 
The Australian labidostomid fauna was 
summarized by Atyeo and Crossley (1961a) who 
described two species of Labidostoma' Kramer 
which are now placed in Sellnickiella (Sellnickiella) 
Feider and Vasiliu, 1969 (Bertrand 1990a): 
Sellnickiella (S.) womersleyi (Atyeo and Crossley) 
and S. (S.) adelaideae (Womersley) 2 . These authors 
(Atyeo and Crossley 1961b) also described some 
new species from New Zealand belonging to both 
Sellnickiella and Labidostoma (Atyeonella) (Feider and 
Vasiliu 1969; Bertrand 1990a). Others known 
species of Sellnickiella are restricted to southern 
hemisphere (Feider and Vasiliu 1970; Feider, 
Vasiliu and Calugar 1974; Bertrand 1990b; Bertrand 
and Theron 1992). 
Although labidostomids are worldwide in 
distribution, they show biogeographic patterns at 
the generic or infrageneric level which allow us to 
consider them as good indicators of past 
relationships between continents. The homogeneity 
of the characters as their originality justify the fact 
that they constitute the suborder Labidostomatina 
(= Labidostomina) amongst the heterogeneous 
order Actinedida with a small number of valid 
genera (only four). Collections from the southern 
continents are still scarce, and increased 
knowledge is leading to a constant improvement of 
' This generic name is either spelt Labidostoma or Labidostomma 
by various authors. Etymologically, the Greek root 'stoma' (for 
mouth) is correct. This term was used by Oudemans (1904) 
who named the family Labidostomidae correcting the error of 
Kramer (1879). According to the International Code of 
Zoological Nomenclature, the valid family group name is 
Labidostomatidae, although the first genus described was 
Nicoletia Canestrini and Fanzago, 1877, and the term 
Nicoletiellidae (Canestrini, 1891) has been used by several 
authors (see Steyskal, 1970). 
! Feider and Vasiliu (1969) wrongly attributed S. ‘wommerslnji’ 
to Womersley (1935). 
traditional classification patterns, mostly based on 
morphological characters of palearctic species. 
Grandjean (1942) stated that the division of the 
genus Labidostoma was untimely. However, 50 
years after, new data have shown four main 
groups, each assigned generic status: Eunicolina, 
Akrosloma, Sellnickiella and Labidostoma (Bertrand 
1990a). Labidostoma is worldwide in distribution, 
and Sellnickiella is restricted in southern 
hemisphere. Description of a new' Australian 
species is a contribution towards our knowledge of 
the labidostomid fauna of tire southern continents. 
The specimens discussed below are all lodged in 
the Western Australian Museum, Perth (WAM) 
and are stored in alcohol. Three were dissected and 
cleared in lactic acid. The following abbreviations 
are used: 
ap.m.: antiaxial cheliceral appendice 
apol, apo2, apo3, apo4, apo sej .: ventral apodemes 1 
to 4 and sejugal apodeme 
bo.a, bo.p: trichobothria, anterior and posterior 
c/m, chb: cheliceral setae 
da, db, dc, dd, de: paired opisthosomatic setae of 
dorsal files 
E: eye 
FE: frontal eye 
ga, ge, gr, gm: fundamental paired aspidosomal 
setae (except trichobothria) 
la, lb, Ic, Id, le: paired opisthosomatic setae of lateral 
files 
ly: lateral lyrifissure of dorsal shield 
LE: lateral eye 
LL: adoral lateral lips 
nut, mb: usual paired infracapitular setae 
p: pores of the cuticle 
P1, P2, P3: paraproctal setae 
SL: superior lip (labrum) 
fa, tn, li: antiaxial, paraxial, and inferior terminal 
teeth of fixed digit of chelicera 
tr: tracheal trunk 
