Lepidodermella aff. squamata (Dujardin, 1841)

Fig. 36

Chaetonotus squamatus Dujardin, 1841: 664, fig. 18.

Locus typicus

France.

Material examined

POLAND • 2 adults; Kraków, Botanical Garden, Jubilee Greenhouse, site 2; 50°03'38" N, 19°57'30" E; 15 Nov. 2013; M. Kolicka leg.; NHC (photomicrographs, also in the author's collection).

Distribution

Lepidodermella squamata is a widely distributed species or, more precisely, in the light of the current data, it represents sets of cryptic or morphologically similar species noted in Europe, inter alia reported from Bulgaria (Valkanov 1937), Germany (Remane 1935–36), Great Britain (Martin 1981), Italy (Mola 1932), Poland (Roszczak 1936; Kisielewska & Kisielewski 1986 a, 1986 b, 1986 c), Romania (Rudescu 1967), Sweden (Kånneby 2011) and Switzerland (Greuter 1917); also reported from Argentina (Grosso & Drahg 1984), Australia (Hochberg 2005), Brazil (Kisielewski 1991), Canada (Schwank 1990), East Africa (Daday 1910), India (Naidu & Rao 2004), Israel (Kisielewski 1999), Japan (Sudzuki 1971), South Korea (Lee & Chang 2000), the United States (Bryce 1924) and Uruguay (Cordero 1918).

Remarks

Lepidodermella squamata (Dujardin, 1841) is one of the four earliest described gastrotrich species (Balsamo et al. 2014). This taxon is distributed worldwide and is very common in very different habitats (from freshwater and brackish psammon to micro-reservoirs in bromeliad leaves); however, in light of molecular data and on the basis of morphological evidence, it constitutes not one but at least a few morphologically very similar species, i.e., a complex of pseudocryptic or cryptic species (Fregni et al. 1998; Kånneby et al. 2012).

Both of the specimens reported here corresponded well with the original species description (Dujardin 1841) and with later records and the emended descriptions by Balsamo (1983) and Kisielewski (1984, 1997 a) (Fig. 36). A detailed discussion of the shape of the scales and comparisons between the studied specimens and L. squamata in the literature are considerably impeded by the noticeable differences in the shape and distribution of the scales that were presented by various authors and by intraspecific variability (e.g., Rudescu 1967; Roszczak 1969; Balsamo 1983; Schwank 1990; Kisielewski 1997 a), but the type and shape of the scales in the main covering remain consistent with Balsamo (1983) and Kisielewski (1984, 1997 a). All of the main morphometric characteristics of L. aff. squamata are within the range given in the literature (Rudescu 1967; Roszczak 1969; Balsamo 1983; Schwank 1990; Kisielewski 1984, 1997 a). The body length of studied adult specimens varied from 146.2 to 153.5 μm; the length of the pharynx from 45.7 to 47.3 μm; the intestine length from 75.5 to 82.1 μm; there were 19 total longitudinal rows of scales (5D +4DL+4L+4LV+ 2V), with 29–31 scales in the central row. The main clear differences between the studied specimens and L. squamata are the possession of one pair of scales with keels and rudimental but rigid spines on the dorsolateral area of the furcal appendages. Scales with keels or spines were listed neither in the original description nor in the main taxonomic reports on L. squamata; thus, I could not determine that the specimens undoubtedly belonged to this nominal taxon. Moreover, the present specimens possessed three pairs of dorsal sensory bristles, but this features cannot be a valid diagnostic character, since it was omitted in the original description and most previous works.