Lepidocyrtus cf. pallidus Reuter, 1890

Mateos, Eduardo & Winkler, Daniel, 2018, New data clarifying the taxonomy of European members of the Lepidocyrtus pallidus - serbicus group (Collembola, Entomobryidae), Zootaxa 4429 (3), pp. 548-568 : 555-556

Lepidocyrtus cf. pallidus Reuter, 1890

Figs 3b, 9‒10 ., Tab 1

Material examined. Eight females on slides from compost in a private garden, Tjöme ( Norway), position N59º09’ 0760” E10º25’55.57”, deposited at the UB (sample LP362), 6.iv.2014, Arne Fjellberg leg. Three females on slides from olive plants soil imported from Germany, Oslo ( Norway, exact position unknown), deposited at the UB (sample LP379), 15.v.2014, Arne Fjellberg leg. Two specimens on slides (unknown sex) from vegetable cultures in Davis Station , Australian Antarctic Territory ( Antarctica), position S68°34’36” E77°58’03”, deposited at the SAM (sample LP540).

Remarks. All specimens have the same color pattern ( Fig. 3b) and match the description previously done for L. pallidus (of the internal basal ungual teeth one tooth much larger than the other, labial chaetotaxy M1M2rEL1L2, dorsal cephalic and body macrochaetae formula A0A2a A2S3Pa5 / 00/0101+2, see Figs 4‒8 ) with the following differences: specimens from samples LP362 and LP540 with abd.IV chaeta F2 as smooth mesochaeta and located above chaeta E2 ( Fig. 9 ). Specimens from sample LP379 with bilateral asymmetries on abd.IV dorsal chaetotaxy, with chaeta F2 as ciliated macrochaeta (and below E2, Fig. 6 ) on one side, and as smooth mesochaeta (and above E2) on the other side of the body ( Fig. 9 ). Also two specimens from sample LP362 and one specimen from sample LP379 bear (asymmetrically) on abd.IV one extra accessory chaeta of trichobotrium T2 located between chaetae m and a (chaeta m’) ( Fig. 10 ).

Discussion. Hüther (1971) described the species L. weidneri as closely related to L. pallidus . He pointed out that the main differences between the two species were the morphology of the internal basal ungual teeth (subequals in L. pallidus and one tooth much larger then the other in L. weidneri ), the labial chaetotaxy (with r chaeta strongly reduced or vestigial in L. pallidus , and R chaeta reduced and ciliated in L. weidneri ) and the dorsolateral abd.IV chaetotaxy (with chaeta F2 as ciliated macrochaeta in L. pallidus , and smooth mesochaeta in L. weidneri ). Also Hüther gave importance to the relative position of chaetae F2 and E 2 in abd.IV: F2 located below E 2 in L. pallidus , and F2 located above E 2 in L. weidneri .

The morphology of the unguis of all the specimens studied is like that of L. weidneri ; the variability in the position and shape of chaeta F2 of abd.IV in the specimens of sample LP379 is congruent with both the species L. pallidus and L. weidneri ; as all specimens have labial chaeta r vestigial , we identified them as L. cf. pallidus . Specimens from samples LP362 and LP540 have abd.IV chaetotaxy like L. weidneri and labial chaeta r like L. pallidus ; as all specimens have labial chaeta r vestigial , we also identified them as L. cf. pallidus . Besides their morphological similarity, these two species have been found in the same habitat by different authors, and seem to be associated with humanized environments. L. pallidus was originally described from Finland basing on specimens collected in a greenhouse in Helsinki ( Reuter 1890), and the subsequent appointments with descriptions have been done also in humanized environments such as flowerpots in a house in Finland, factories of cork agglomerates in Portugal ( Gisin 1965), compost and indoor flowerpots in Finland ( Fjellberg 2007), garden compost in USA (present paper), plant soil in Norway (present paper), and soil of highly humanized area in China (present paper). L. weidneri was originally described from Hamburg ( Germany) basing on specimens collected in compost soils ( Hüther 1971), and subsequent descriptions have been done basing on specimens also collected in humanized habitat such as indoor flower pot in Finland ( Fjellberg 2007). All the specimens described as L. cf. pallidus in the present paper have been collected in humanized environments too: plant soil and garden compost in Norway, and vegetable cultures in Antarctica. This kind of habitat is shared with L. fimicolus Mari-Mutt, 1988 , a non European species morphologically very similar to L. pallidus and L. weidneri , that was originally described from Vieques Island ( Puerto Rico) basing on specimens collected under cow dung ( Mari-Mutt 1988), and subsequently recorded as domestic infestation in California (Bellinger et al. 1996‒2017).

Described morphological differences between L. pallidus , L. weidneri and L. fimicolus are scarce. The variability of the color pattern on head and body of L. fimicolus (from light violet-gray to almost black, Mari-Mutt 1988) overlap those of described for L. pallidus and L. weidneri ( Reuter 1890, Hüther 1971). Soto-Adames (2000) found that only the presence of chaeta Li on abd.II in L. fimicolus separates this species from the other two, while Wang et al. (2003) also noted that macrochaeta m7a on abd.III is absent in L. fimicolus , while it is present in L. pallidus and L. weidneri ( Hüther 1971) . All three species share a differential character within L. pallidus – serbicus group which is the length of the abd.IV chaeta D1p (double than length of abd.IV chaeta T3, Fig. 10 , Table 1). Only some specimens of L. arrabonicus have similar length of this chaeta.

L. fimicolus , L. pallidus and L. weidneri are ecologically and morphologically very close species and difficult to differentiate (see Table 1). They have always been found in humanized habitats and have similar color pattern and very similar chaetotaxy. The variability described in the present paper for the specimens of L. cf. pallidus add controversy to the matter. With the current information is not possible to know the true identity of L. cf. pallidus , and we think only molecular studies simultaneously including specimens of L. pallidus , L. weidneri and L. fimicolus will shed light on this topic. The molecular study made by Soto-Adames (2002), including species L. pallidus (from under bark of dying crab apple tree, Urbana, Ilinois) and L. fimicolus (from moist mowed lawn in Aguadilla, Puerto Rico), concluded that both species are closely related (syster species with 14% divergent in COI gene). Sequences of the COX II gene obtained from specimens of L. cf. pallidus from samples LP362 and LP379 were used in the phylogenetic analysis done by Mateos et al. (2018). In this analysis, all the sequences belong to the same haplotype, indicating that they all belong to the same species. So we can conclude that the variability observed in the morphology and position of chaeta F2 on abd.IV in L. cf. pallidus correspond to intraspecific variability.

Figures

FIGURES 9–10. Lepidocyrtus cf. pallidus: 9, partial abd.IV chaetotaxy, broad black circles—broad ciliated macrochaetae, small black circles—thin ciliated macrochaetae, open circles—mesochaetae, triangles—fan-shaped chaetae, x—trichobotria; 10, abd.IV trichobotrial complex of specimens with duplicated chaeta m (chaeta m’).

FIGURES 4–5. Lepidocyrtus pallidus: 4, labial triangle (left side) and postlabial chaetotaxy; 5, dorsal head chaetotaxy (left side), broad circle—long ciliated macrochaetae, small circle—short ciliated macrochaetae.

FIGURES 6–8. Lepidocyrtus pallidus: 6, abd.IV chaetotaxy, broad black circles—broad ciliated macrochaetae, small black circles—thin ciliated macrochaetae, open circles—mesochaetae, triangles—fan-shaped chaetae, x—trichobotria, crossed circle—pseudopore; 7, abd.IV trichobotrial complex; 8, abd.V chaetotaxy, broad black circles—long ciliated macrochaetae, small black circles—short ciliated macrochaetae.