Two new species of phthiracaroid mites (Acari, Oribatida, Phthiracaroidea, Steganacaridae) from Australia

: Descriptions of two new species of phthiracaroid ptyctimous mites Plonaphacarus trojani sp. nov. and Notophthiracarus trojani n. sp. from Australia are dedicated to an oustanding Polish ecologist and entomologist Professor Przemysław Trojan at his 80th birthday.

Ptyctimous mites are a special group of Oribatida (Norton & Behan-Pelletier 2009) ptychoid body form, and charactersied by the ability of folding propodosoma close to opisthosoma in order to protect the ventral region and appendages.
Two new species described below belong to two different genera of family Steganacaridae Niedbała, 1986: Plonaphacarus Niedbała, 1986and Notophthiracarus Ramsay, 1966 Notophthiracarus is the genus most abundant in Australia and comprises over 60 species, however, the genus Plonaphacarus is represented only by nine species (Niedbała 2000(Niedbała , 2006 Colour brown. Surface of body covered with coarse structure but not foveolate. Prodorsum without lateral carinae. Sigillar fields weakly visible, median shorter than laterals. Sensilli similar to interlamellar setae, long, with flagelliform distal end, sparsely covered with cilia. Interlamellar setae also flagelliform but lamellar and rostral setae pointed distally, rostral setae rigid. Notogaster with 15 pairs of very long, thick setae, majority of them flagellate distally but setae dp d2, ep e2, h3, p 3 pointed distally. All setae sparsely covered with small spines. Setae c3 and c3 located at anterior margin, setae c2 slightly remote from border. Vestigial setae not visible. Two pairs of lyrifissures ia, im present. Ventral region. Setae h of mentum as long as distance between them. Formula of genital setae: 4+2: 3. Anoadanal plates with 5 pairs of long setae covered with cilia. Setae ad3 and ad2 longer than other setae. Only setae ad3 pointed distally, other setae flagellate. Chaetome of legs of "complete type", setae d of femora bifurcate and located at distal end of article.
Types Colour brown. Surface of the prodorsum covered with foveae. Surface of notogaster with irregular furrows.
Prodorsum with prominent median crista. Lateral carinae absent. Sigillar fields not discerned. Posterior furrows long and well discernible. Sensilli long, narrow, bent in proximal end, covered with small cilia in distal half. Setae small, filiform, smooth.
Notogaster with well marked tubercules, each tubercule bears one seta. Total number of setae is 15 pairs, all fine, smooth, small (cj /cj-dj = 0.3). Setae cj_3 remote from anterior margin, setae cj and c2 more than setae c3. Vestigial setae not observed. Two pairs of lyrifissures, ia and im, present.
Ventral region. Mentum of infracapitulum with seatae h slightly shorter than distance between them. Arrangement of genital setae 6:3. Anoadanal plates with 5 pairs of setae. All anal and adanal setae minute, adanal setae situated near proximal border a/plates. Legs setation of "complete type". Seta d on femora I distinctly remote from distal end of segment.
Holotype and three paratypes in CSIRO, four paratypes in DATE.
Comparison. The new species is very similar to Notophthiracarus admirabilis Niedbała & Colloff, 1997 by the shape of prodorsum with the prominent median carina, small and fine setae of body, formula of genital setae 6: 3, small setae of anoadanal plate, adanal situated near paraxial border. The principal differences are the presence of notogastral tubercules bearing the setae and shape of sensilli, long, narrow, covered with cilia.