Metaphalangium Roewer, 1911

Mitov, Plamen G., Perkovsky, Evgeny E. & Dunlop, Jason A., 2021, Harvestmen (Arachnida: Opiliones) in Eocene Rovno amber (Ukraine), Zootaxa 4984 (1), pp. 43-72 : 51

Genus Metaphalangium Roewer

Type species. Phalangium propinquum Lucas [= Metaphalangium cirtanum (C. L. Koch) ] ( Roewer 1911; Staręga 1984), by original designation.

Remarks. The new fossil specimens described here show similarities to representatives of the extant genera Phalangium Linnaeus , Dasylobus Simon , and Metaphalangium Roewer ; mainly the presence of a process on the palpal patella, the shape, armament and position of the ocular tubercle, the slender legs and its light color (in amber) with a silver shine. These new fossils are probably juveniles or immatures due to their small size and the underdeveloped armament on the ocular tubercle. Therefore, we compared these specimens with the juveniles of some extant species of the above-mentioned genera and found that the new fossil species is most similar to juveniles of the genus Metaphalangium , and especially to representatives of M. cirtanum ( Fig. 12 ), which is also the most widespread extant species of the genus. The similarity (see Figs 9–14 ) between these is expressed in the position and structure of the ocular tubercle, the presence of a medio-distal prominence of the palpal patella, the proportions of the pedipalpal segments, the slender legs, and especially in the presence of stout spine-like setae on the medial surface of the palpal patella and tibia ( Figs 11–12 , 14 ).

Metaphalangium Roewer so far comprises about 13 recent species, distributed in the Mediterranean region, the Balkans, the Near East, and the Caucasus. Only M. albounilineatum ( Algeria, Libya, Morocco, Tunisia, and southern Italy) and M. cirtanum (circum-Mediterranean region) have a wider range ( Mkheidze 1952; Martens 1978; Crawford 1992; Staręga 1984, 2004; Prieto 2003, 2008; Özdikmen et al. 2010; Barrientos et al. 2017; Kury et al. 2020). The present discovery in Rovno amber is a new genus record for the fossil harvestman fauna.

Figures

FIGURES 11–12. Metaphalangium spp., detail of the anterior prosoma and pedipalps. 11 Metaphalangium martensi sp. n. (holotype, SIZK K-3197, from Rovno amber, Klesov, Pugach quarry, Ukraine; late Eocene). Note the palpal patella with small and blunt medio-distal prominence (black arrow) with stout spine-like setae and mesial brush of stout spine-like setae on palpal tibia (white arrow), ventral view. 12 Comparative image of the extant species Metaphalangium cirtanum (C. L. Koch) (juvenile from Albania: Zvërnec), white arrows indicate palpal patella and tibia, mesially covered with stout spine-like setae, dorso-lateral view. Scale bars: 0.3 mm.

FIGURES 9–10. Metaphalangium martensi sp. n., holotype, SIZK K-3197, from Rovno amber (Klesov, Pugach quarry, Ukraine), late Eocene (ca. 36–37 Ma). 9 Dorso-lateral overview of the complete animal. 10 Detail of body in dorso-lateral view. Scale bars: 2 mm.

FIGURES 13–14. Metaphalangium martensi sp. n., paratype, SIZK K-1254, from Rovno amber (Klesov, Pugach quarry, Ukraine), late Eocene. 13 Lateral overview of the complete animal (white arrow points the pedipalps). 14 Detail of pedipalps, lateral. Scale bars: 13: 1 mm; 14: 0.5 mm.