Litocampa mendesi, Reboleira, Ana Sofia P. S., Sendra, Alberto, Gonçalves, Fernando & Oromí, Pedro, 2010

Reboleira, Ana Sofia P. S., Sendra, Alberto, Gonçalves, Fernando & Oromí, Pedro, 2010, The first hypogean dipluran from Portugal: description of a new species of the genus Litocampa (Diplura: Campodeidae), Zootaxa 2728, pp. 50-56 : 51-54

Litocampa mendesi new species Sendra & Reboleira

Figs. 1–3

Type specimens. Holotype Ψ, 3.4 mm, Gruta de Ibne Ammar, Algarve, Portugal, 13.III.2009, S. Reboleira leg., preserved in ethanol 70%, deposited at MVHN. Paratypes: 8 ɗ, 9 Ψ, same data as holotype, preserved in 70% ethanol, deposited as follows: 2 ɗ, 3 Ψ in MVHN; 2 ɗ, 2 Ψ in SR; 2 ɗ, d 2 Ψ in DZUL; 2 ɗ, 2 Ψ in MZG. Gold-palladium coated SEM-scanned specimens (2 ɗ, 2 Ψ) on same stub, same data as holotype, deposited in SR.

Other specimens. Gruta de Ibne Ammar, Algarve, Portugal, 13.III.2009, S. Reboleira leg., 36 specimens preserved in either 70% or absolute ethanol, distributed to MVHN, SR, DZUL.

Etymology: This species is dedicated to the Portuguese entomologist Luís F. Mendes, who has contributed greatly to the knowledge of subterranean Zygentoma.

Description. Body length (excluding cerci) 1.92–4.20 mm. Antennae longer than half the length of the body, 0.52 to 0.87× body length. Cercal length about half the body length (0.56–0.57× for two intact cerci) ( Table 1, Fig. 1 ). Cuticle completely unpigmented, without ornamentation. Clothing setae thin and glabrous.

Holotype Paratypes

n Mean Range Head-plus-thorax length (mm) 0.83 13 0.76 0.58–1.05 Body length (mm) 3.40 13 3.21 4.20–1.92 Antennal length (mm) 1.86 13 1.98 1.04–2.36 Antennomeres 27 13 26 26–29 Metathoracic leg length (mm) 0.86 13 0.96 0.61–1.25 Cercal length (mm) - 2 0.91 1.82–2.00 Adult antennae with 26 to 29 doliiform articles; bacilliform sensillum of third article located between macrochaetae d and e (ventral position). Up to six sensilla in a 14–16-Μm-long trough or “ gouge ” ( Bareth & Condé 1981) in a distal verticil on each article. Cupuliform organ of apical article with narrow orifice, and with five sensilla with two collarettes each. Frontal process slightly protuberant with three macrochaetae near the tip, anterior chaeta slightly longer than two posterior chaetae (holotype: 11/10/10 Μm); anterior chaeta smooth, posterior chaetae each with thin distal barb. Three macrochaetae along each antennal insertion line, with 3–5 thin distal barbs, intermediate macrochaeta slightly longer than anterior and posterior macrochaetae (holotype: 20/25/21 Μm). Labial palps with 80–100 neuroglandular setae.

Nota elongated, especially meso- and metanotum. Distribution of macrochaetae typically 3+3 (ma, la, lp) on pronotum and mesonotum, 2+2 (ma, lp) on metanotum. All macrochaetae long with barbs on distal two-thirds. Marginal setae poorly differentiated from clothing setae, only marginal setae nearest to latero-posterior macrochaetae longer, with 2–8 thin distal barbs. Metathoracic tarsi extending beyond abdominal segment V. Femur with a dorsal macrochaeta barbed on distal two-thirds and twice the length of the ventral tibial macrochaeta (holotype: 87/40 Μm). Ventral tibial macrochaeta with 3–4 distal barbs. Calcars with long barbs extending from their bases. Two rows of barbuled setae on ventral face of the tarsus, the three subapical setae smooth. Claws small, with fine transverse striae, clearly layered, small lateral crests slightly differentiated, telotarsal process glabrous and setiform ( Fig. 2 ).

All macrochaetae on urotergites relatively long and thin. Urotergites I and II without macrochaetae, urotergites III with 1+1 ma, urotergites IV with 1+1 ma, 1+1 or 0+0 la and 1+1 lp, urotergites V to VII with 1+1 ma, 1+1 la and 1+1 lp, urotergite VIII with 1+1 mp and 3+3 lp, and abdominal segment IX with 6+6 lp. Macrochaetae ma with fine barbs on distal half, reaching the bases of the marginal posterior setae on the anterior tergites and only exceeding at the posterior tergites. Macrochaeta la the shortest, about half the length of lp, both with barbs on distal two-thirds. Clothing setae on abdominal segments IX and X thicker and longer than on other segments. Urosternite I with 6+6 macrochaetae, urosternites II to VII with 4+4 macrochaetae, urosternite VIII with 1+1 macrochaetae. Urosternite macrochaetae shorter and with longer, thicker barbs than those of urotergites. Styli typical, apical seta of each stylus with two barbs at its base, subapical setae smooth, and sternal setae bifurcated, sometimes with additional small, fine barbs. Long macrochaetae of cerci distributed in 1 to 4 verticils on each article, with distal barbs; clothing setae scarce.

In males, urosternite I without glandular g1 -setae on posterior margin; appendages subcylindrical and clearly widened, with six glandular a1 -setae in apical and latero-internal field of glandular a2- setae ( Fig. 3 a). In females, appendages of urosternite I distinctly subcylindrical, with six apical glandular a1- setae ( Fig. 3 b).

Affinities. Litocampa mendesi n. sp. differs from all other Litocampa species in the following combination of characters: presence of a dorsal macrochaeta on the femur; presence of ma macrochaetae on urotergites I–VII; a couple of lp macrochaetae on urotergites I–VII. Condé (1991: 245) wrote in the description of Litocampa henryi from the Grottes de Blano (Saône-et-Loire, France) that it “exhibits a surprising mixture of taxonomic characters which upset the generic criteria used at present.” This statement applies to Litocampa mendesi as well. Litocampa drescoi Condé, 1949 shares with L. mendesi the minute size and the very small claws, but differs in other features such as the ma macrochaetae on urotergite VIII (mp in L. mendesi n. sp.), the presence of a field of glandular g1- setae on the posterior margin of the male urosternite I, and the higher number of antennomeres.

Litocampa currently contains 31 known species, 13 of which are European ( Bareth 1999, 2006; Paclt 1957; Sendra et al. 2003) and 18 occur on other continents ( Allen 1994, 2003, 2006; Silvestri 1933a, b; Wygodzinsky 1944b). The distribution of the European species ranges from the Atlantic region of the Iberian Peninsula to beyond Central Europe. However, several Litocampa species have been recently collected in several Mediterranean localities, always in caves: Mallorca (Balearic Islands, Spain), Caroig Platform (Valencia, Spain) and Gador Mountain (Almería, Spain) and also on Madeira Island ( Portugal) (A. Sendra, unpubl.). Litocampa mendesi n. sp. is the southernmost described Litocampa of Europe, more than 600 km from the known range of L. zaldivarae Sendra, Salgado & Monedero, 2003 in the Cantabrian Mountains.

Ecology. All specimens of Litocampa mendesi n. sp. were obtained in Gruta de Ibne Ammar (UTM 2958577 E, 4114 44 N) located on the left bank of the Arade estuary at 10 metres asl. This species was not found in any other locality along more than 60 km, between the Ibne Ammar cave and the easternmost sampled cave, located in Moncarapacho. Humidity was 100% throughout the year, and the temperatures of the cave were constant, with air temperature 20.8 ºC and soil temperature 18 ºC.

Gruta de Ibne Ammar is also inhabited by other hypogean arthropods known from the Algarve and which present different degrees of adaptation to subterranean life ( Machado 1946, 1951; Reboleira et al. in press; Vandel 1946;). These include detritivorous species such as the woodlouse Trogloarmadillium machadoi Vandel, 1946 , some unidentified Collembola, a new coletiniine silverfish (Zygentoma) and the cholevine leiodid beetle Speonemadus angusticollis (Kraatz, 1870) , as well as predators such as the centipede Lithobius dimorphus Machado, 1946 , the recently described pseudoscorpion Titanobochica magna Zaragoza & Reboleira, 2010 ( Reboleira et al. 2010) and the leptonetid spider Teloleptoneta syntetica ( Machado, 1951) .

Litocampa mendesi n. sp. was collected only on the salty substratum at the bank of an anchialine lake, which may suggest halophilic preferences. However, Litocampa mendesi n. sp. may not be confined to this particular cave habitat. The morphological modifications of the body, especially the elongation of the thoracic segments ( Fig. 1 ), are adaptations to hypogean life, but are not striking troglobiomorphies (sensu Christiansen 2005) as typically observed in Campodeidae that live exclusively in caves (the “ milieu souterrain profond ” or mesocavernous deep substratum, Juberthie et al. 1980a). These troglobiomorphic character states of Campodeidae include increase in body size, elongation of the appendages, and multiplication of the sensilla in the cupuliform organ of the apical antennomere ( Bareth & Pagés 1994).

Seven of the 14 Litocampa species known from Europe ( L. vandeli Condé, 1947 , L. cognata Condé, 1948 , L. humilis Condé, 1948 , L. tuzetai Condé, 1948 , L. henry Condé, 1991 , L. hubarti Bareth, 1999 , L. mendesi n. sp.) exhibit only slight troglobiomorphic adaptations and are thus more similar to epigean campodeids. They have reduced body size, slightly elongated appendages (antennae and cerci not longer than the body, metathoracic legs not reaching the tip of the abdomen), thirty antennomeres at the most, four or five simple sensilla in the cupuliform organ of the antennal apex, and reduced claw ridges. All these species, except Litocampa mendesi n. sp., are distributed over vast ranges, including several karstic areas. Litocampa humilis , for example, occurs across France ( Bareth 2006) and central Europe. Some of these species have been found in hypogean environments: Litocampa vandeli and L. cognata in the “ milieu souterrain superficiel ” (sensu Juberthie et al. 1980a) of the French Ariège ( Bareth 1983), and L. humilis in artificial cavities (A. Sendra, unpubl.).

In a large cave east of Cluj ( Romania), a subspecies of Litocampa humilis : L. humilis comani Condé, 1991 occurs abundantly only in a room in the deep galleries (Oana Moldovan, pers. comm.). This subspecies is characterized by a cupuliform organ that carries 14 sensilla with fingerlike expansions—a clearly troglobiomorph character state which justified its description as a subspecies. Another case is the wide habitat in some species of Litocampa , as in L. tuzetae which has also been found in epigean habitats ( Condé 1948). This vertical distribution of Litocampa spp. in different underground environments has been observed in other groups with cave species such as Coleoptera ( Juberthie et al. 1980b) and other arthropods ( Gers 1998), as well as in other genera of Campodeidae such as Podocampa ( Bareth 1983) .

Figures

FIGURE 1. Habitus of Litocampa mendesi Sendra & Reboleira n. sp. (Scale: 1 mm).

FIGURE 2. Litocampa mendesi Sendra & Reboleira n. sp. Mesotarsal claw and lateral pretarsal setae, scanning electron microscope photograph. (white arrow: small lateral crests; scale: 20 µm).

FIGURE 3. Litocampa mendesi Sendra & Reboleira sp. n. Hemiurosternite I. a) male, b) female. (Scale: 0.1 mm).