(Fig. 3A–G)
Measurements of holotype: prodorsum: length 308, width 222, height 111, setae: ss 58, in 40, le 38, ro 45; notogaster: length 566, width 384, height 353, c 1, h 1 and ps 1 106; genitoaggenital plate 146×126, anoadanal plate 227×136.
Description. Medium-sized species. Color brown. Surface of body roughened.
Prodorsum. Sigillar fields, posterior furrows and lateral carinae absent. Sensilli long, crescent-shaped, pointed distally, covered with small spines; other setae, except vestigial exobothridial, spiniform, rough, similar in length, ss > ro > in > le.
Notogaster with 20 pairs of rather short (c 1/ c 1- d 1=0.7), rigid setae covered with small spines in distal half, pointed distally. Additional setae in rows h and ps. Setae of row c 1 and c 3 situated near anterior border, setae c 2 distanced from border. Vestigial setae f 1 located posterior of setae h 1. Two pairs of lyrifissures im and ip present.
Ventral region. Setae h of mentum shorter than distance between them. Genitoaggenital plates with 9 pairs of genital setae with arrangement 9(4+5): 0. Anoadanal plates each with 5 pairs of adanal setae covered with small spines, 3 anterior shorter than two posterior; anal setae slightly longer, rough, an 1 longer than an 2.
Legs. Formulae of setae and solenidia of “complete type”. Setae d of femora I short, thick, spiniform, bent distally and remote from distal end of article.
Material examined. Holotype: Vic. Otway Ranges, Maits Rest, 10 km W of Apollo Bay, 38°45'S, 143°34'E, litter & moss from Nothofagus cunninghamii forest, 7 December 2014, leg. A. Szczykutowicz.
Etymology. The specific epithet lunatus is Latin for “crescent-shaped” and alludes to the shape of sensilli.
Comparison. The new species may be differentiated from its congeners first of all by the crescent-shaped sensilli and presence of two pairs of lyrifissures im and ip. Slightly similar Austrophthiracarus radiatus Balogh et Mahunka, 1978 has fusiform shape of sensilli, distinct sigillar fields of prodorsum, much more notogastral setae (27–31 pairs) and presence of lyrifissures ia and im.