Parahistricostoma tuberculatum (C. L. Koch & Berendt, 1854 ), 2021

Mitov, Plamen G., Perkovsky, Evgeny E. & Dunlop, Jason A., 2021, Harvestmen (Arachnida: Opiliones) in Eocene Rovno amber (Ukraine), Zootaxa 4984 (1), pp. 43-72 : 63

cf. Parahistricostoma tuberculatum (C. L. Koch & Berendt, 1854)

Figs 25–27

Material examined.. UKRAINE: SIZK UA- 1565, Rovno amber, precise locality unclear; late Eocene. Syninclusions: none.

Description. A juvenile covered by a white emulsion concealing the dorsal granulation and the armature of the scutum ( Fig. 25 ). With L: 0.50; prosoma width: 0.27; abdomen width: 0.28; ocular tubercle elliptic ( Fig. 26 ), with length: 0.06 and width: 0.08; diameter of each lens 0.03; Palps with article lengths: Fe: 0.308; Pa: 0.238; Ti: 0.238; Ta: 0.14. Palpal articles (except trochanters) ventrally with clavate setae (L: 0.056) (see Figs 26–27 ). The tarsus of each leg is one-segmented ( Fig. 25 ) with a length of: Ta I: 0.28; Ta II.–IV.: 0.25, respectively.

Remarks. Given the shape of the ocular tubercle, the proportions of the pedipalps, and the shape of their segments, this juvenile most probably belongs to Parahistricostoma tuberculatum , too. The length of the body, the single tarsal segments and their length, indicate that this juvenile nemastomatid, by analogy with other extant nemastomatid species, could be the first or the second juvenile stage (cf. Immel 1954: figs 8, 10).

Figures

FIGURES 25–27. cf. Parahistricostoma tuberculatum (C. L. Koch & Berendt, 1854), juvenile, SIZK UA-1565, from Rovno amber (precise locality unclear), Ukraine; late Eocene. 25 Dorso-lateral overview of the complete animal. 26 Detail of 25, showing anterior prosoma and pedipalps with clavate setae (arrowed), dorso-lateral view. 27 Detail of 26 close up showing palpal segments with clavate setae; note also the head of clavate seta (arrowed), lateral view. Scale bars: 25: 1 mm; 26: 0.2 mm; 27: 0.05 mm.