Hadzinia Šilhavý, 1966

Novak, Tone & Kozel, Peter, 2014, Hadzinia ferrani, sp. n. (Opiliones: Nemastomatidae), a highly specialized troglobiotic harvestman from Slovenia, Zootaxa 3841 (1), pp. 135-145 : 143-144

Hadzinia Šilhavý, 1966

Diagnosis. Genus of very small (below 1.5 mm), long-legged (leg II up to 23-times the length of body) troglobiotic Nemastomatidae , characterized by distinctive male genital morphology. Ocular tubercle low or absent, eyes reduced. Male cheliceral apophysis and cheliceral gland openings absent. Pedipalps very long, 5.2−5.7-times as long as body, tarsus proximally conspicuously bent to ventral side. Truncus thin, base bifurcated. Glans truncated cone-like to elongate barrel-like shaped, slightly wider than truncus. Glans terminally truncated, with two lateral humps encompassing furrow and subapically emerged stylus on the ventral side in the middle of furrow, pointed in dorsal and ventral view. According to present knowledge, of scattered distribution in the central and western Dinaric region. Currently two described species (but compare Karaman 2013).

Karaman (2013) suggests that the unusual distribution of Hadzinia and Nemaspela could indicate their relict status as elements of the paleo-European mainland fauna. This is justified, but the distinctive genital morphologies indicate that these two lineages most probably evolved from various ancestors which independently colonized the subterranean environment. While Nemaspela seems to be a subterranean offshoot of the Giljarovia ancestor ( Martens 2006), Hadzinia may have originated from the same ancestor as Pyza or Vestiferum .

It should be noted that Nemaspela femorecurvata Martens, 2006 and N. ladae Karaman, 2013 have been the only species in the genus missing the male cheliceral apophysis, which is also missing in Hadzinia . Dunlop & Mitov (2009) argue that the shape of the male cheliceral apophysis, viewed in isolation, is insufficient to identify the genus, since a few nemastomatid genera may evince a similar shape. Furthermore, its absence in highly adapted troglobionts is per se not a useful characteristic for identification, since it may be just one convergence in a series of several adaptations to subterranean habitats. Therefore, genital morphology is of greatest importance in considering relationships between the studied taxa, as has been established for other opilionid groups ( Derkarabetian et al. 2010). In this way, the external similarities between particular Hadzinia and Nemaspela species imply either general adaptive convergence to the hypogean habitat, or convergence triggered either by living in similar habitats or by preying on comparable prey. All this additionally supports Karaman’s opinion that in these genera we are investigating a special case of evolution within paleo-European mainland fauna with respect to Balkans-Caucasus opilionid congeners. Phylogenetic investigation could contribute much to clarifying the relationships among the alleged taxa.