Ctenolepisma subterraneum Molero, Tahami, Sadeghi & Gaju

Molero, Rafael, Tahami, Mohadeseh Sadat, Gaju, Miquel & Sadeghi, Saber, 2018, A survey of basal insects (Microcoryphia and Zygentoma) from subterranean environments of Iran, with description of three new species, ZooKeys 806, pp. 17-46 : 17

Ctenolepisma subterraneum Molero, Tahami, Sadeghi & Gaju sp. n. Figs 7, 8

Type material.

Holotype (MNCN): female, body length = 7 mm, mounted on slide, labelled "Abu Nasr cave, Shiraz, Fars Province, Iran. 12.XI.2015. Cat. Types N. 2835"; "HOLOTYPE ♀ Ctenolepisma subterraneum sp. n., des. Molero, Tahami, Sadeghi & Gaju, 2018".

Diagnosis.

Very faintly pigmented and medium-sized lepismatid. Distribution of scales and trichobothrial areas as in C. ciliatum . Apical article of the labial palp with almost parallel sides and three sensory papillae arranged in a single row. Pronotum with 9-10 combs of macrosetae, mesonotum with 14 pairs and metanotum with 11 pairs of combs. Prosternum with 2+2 bristle-combs, mesosternum with 1-2 pairs of combs and metasternum with 1+1 combs. Macrosetae of thoracic sternites arranged in one row. Urosternites III-VIII with 1+1 lateral combs. All urosternites without median combs (subgenus Ctenolepisma s. str. sensu Irish, 1987). Urotergite I with 1+1 combs, II-VI with 3+3 combs and VII-VIII with 2+2 combs ( ciliatum -group sensu Mendes, 1982). Urotergite X trapezoidal. Two pairs of styli. Ovipositor with 40 divisions. Male sex unknown.

Description

. Body length: 7 mm. Body fusiform, with the thorax slightly wider than the abdomen, maximum thorax width 1.75 mm. Epidermal pigment very faint, yellowish-brown in alcohol. Scales with brownish pigment (perhaps greyish in live specimens). Most macrosetae are lost, they can be detected by their insertions, when preserved they are almost hyaline to brown-yellowish. Setation of the head with the pattern typical of the genus. Eyes with 12 ommatidia. Antennae broken (maximum length preserved: 2.2 mm). Maxillary palp (Fig. 7A) with the apical article about 5.5 times longer than wide and as long as the penultimate. Apical article of the labial palp about 1.4 times longer than wide, without any expansion in the inner side, with three sensory papillae arranged in a single row (Fig. 7B). Pronotum with a brush of macrosetae in the central part of the anterior margin, with 2-4 rows of macrosetae. A row of 20-24 short smooth setae extends from the median brush to the anterolateral corner of the pronotum (Fig. 7C). The lateral margins of this notum show 9+10 lateral combs with 2-5 macrosetae each. Mesonotum with 14+14 lateral combs with 1-5 macrosetae (the two anterior “combs” are composed only by one macroseta). Metanotum with 11+11 lateral combs with 1-4 macrosetae (the first composed also by one macroseta). Additionally, the three nota have 1+1 posterolateral combs with 6-8 macrosetae. Anterior trichobothrial areas of the thoracic nota not well visible, but apparently following the same arrangement than in Ctenolepisma ciliatum , i.e., those of the pronotum situated on lateral comb N-3; those of the mesonotum associated with the antepenultimate (N-2) lateral comb and those of the metanotum associated with the penultimate (N-1) lateral comb. All posterior trichobothria associated with the last lateral comb (N) on the three nota.

Prosternum heart shaped, as long as wide at its base and with the hind margin rounded but slightly truncated at the apex (Fig. 7D). It bears 1+1 brushes of thin and long setae in the anterolateral corners and 2+2 oblique combs in the antedistal region; each comb with 11-12 macrosetae arranged in a single row, although the anterior ones are more irregular. Mesosternum slightly longer than wide at its base, with only 1+1 oblique antedistal combs of 11-14 macrosetae arranged in a single row (Fig. 7E), although the comb of the left side is irregular, apparently broken in two close smaller combs (could be interpreted as 1+2 combs). Metasternum wider than long (ratio length/ width about 0.85) with only one pair of combs of 13-14 macrosetae arranged in one row (Fig. 8A). Hind margins of meso- and metasternum slighly truncated. Distance between the combs 1.4-1.5 times the width of a comb. Protibiae 2.9-3.0 times longer than wide; mesotibiae 3.2 times longer than wide and about 1.15 times longer than the protibiae; metatibiae lost. All preserved tibiae with 2 dorsal and 4 ventral macrosetae shorter than diameter of the article (Fig. 8B). Tibiae without scales. Scales of femora rounded.

Urotergite I with 1+1 bristle-combs; urotergites II-VI with 3+3 combs; urotergites VII and VIII with 2+2 combs. Submedian bristle-combs with 6 macrosetae, lateral combs with 6-7, and sublateral combs with 7-10. Urotergite X trapezoidal, somewhat long (its apical part about 0.46 longer than wide at its base), with slightly concave posterior margin and 1+1 combs of 10-11 macrosetae (Fig. 8C). Urosternites I and II without setae, III-VIII with 1+1 lateral bristle-combs with 11-15 macrosetae. Distance between lateral combs of urosternites 4.8-5.6 times wider than the width of a comb (Fig. 8D).

Male sex unknown. In female, two pairs of abdominal styli (they are lost, but their insertions are clearly visible). Inner process of coxite IX about 1.8 times longer than wide at its base and 3.1 times longer than the outer process (Fig. 8E). Ovipositor with 40 divisions, its apex surpassing the tip of the inner process of the coxite IX approximately by its length (Fig. 8E). Apices of gonapophyses unsclerotized. Caudal filaments broken; maximum length preserved 1.3 mm (in a cercus).

Discussion.

The new species is related to C. ciliatum (Dufour, 1831), C. longicaudatum Escherich, 1905 and C. armeniacum Molero, Gaju, Bach & Mendes, 2010, sharing with them the following characteristics: abdominal setation (absence of median combs on urosternites, 3+3 combs of macrosetae on urotergites II-VI), the trapezoidal shape of the tenth urotergite, the distribution of scales on legs (rounded on femora and absent on tibiae and tarsi), the distribution of trichobothria of the nota, and the smooth setae of the anterolateral row of the pronotum. However, all of these species show 5 papillae in the apical article of the labial palp, whilst Ctenolepisma subterraneum sp. n. has 3 papillae. There is only one species of the genus Ctenolepisma that shares this particular characteristic in the labial palp and the aforementioned abdominal characters: C. barchanicum Kaplin, 1985, from the Karakum region in Turkmenistan, but this species is clearly a different taxon because several differences can be detected:

- Number of pairs of styli: C. barchanicum has only one pair of styli, and C. subterraneum sp. n. has two pairs (at least, females);

- Shape and setation of thoracic sternites: Kaplin’s drawings of C. barchanicum reveal that these sternites are clearly rounded at their apex, while in the new species their hind margins are slightly truncated. Moreover, the number of combs in the Turkmenian species is higher (5-8 pairs in the prosternum, 3-4 pairs in the mesosternum and 2 pairs in the metasternum, versus 2, 1-2 and 1 pairs of combs respectively in the Iranian species);

- Shape of the apex of the labial palp: Following Kaplin (1985), the inner side of the apical article of the labial palp is strongly widened in C. barchanicum , while in C. subterraneum sp. n. the labial palp has subparallel sides;

- Number of lateral combs in nota: According Kaplin’s description (in Russian), the Turkmenian species has a lower number of combs in the pronotum (5 pairs), in the mesonotum (8-10 pairs) and in the metanotum (7-9 pairs), while the new species from Iran has respectively 9+10 combs, 14 pairs and 11 pairs of combs;

- Shape of the hind margin of the urotergite X: Kaplin’s drawing of the urotergite X of C. barchanicum shows a convex hind margin, while this is concave in C. subterraneum sp. n.;

- Length and number of divisions of the ovipositor. C. barchanicum has only 12-13 division and the new species has 40 divisions. In spite of this, the length of the ovipositor of C. subterraneum sp. n. is only slightly higher relative to coxites IX.

The genus Ctenolepisma was revised recently in Iran by Kahrarian et al. (2016); then, seven species were considered to occur in this country, if C. mauritanicum (Lucas, 1846), with doubtful status, is included. Ctenolepisma subterraneum sp. n. fits at step 5 of the key of Kahrarian et al. (op. cit.) with the following modifications:

Distribution.

Known only from the type locality, Abu Nasr cave, in Fars province, Iran.

Etymology.

The specific name of the new species refers to its habitat, not common within species of the genus (see next section). Subterraneum is an adjective in the nominative case.

Habitat.

This new species has been found near the cave´s entrance (endogean). This habitat is unusual within members of the genus Ctenolepisma , since most of them are associated to more superficial (epigean) habitats: under stones or vegetal debris, in trunks of trees, etc.