Iranian terrestrial isopods of the family Cylisticidae Verhoeff, 1949 with a description of a new species (Isopoda, Oniscidea)

Abstract In the present study, the terrestrial isopods of the family Cylisticidae in Iran are investigated. Geographical distributions of two formerly reported species from Iran, namely Cylisticoides angulatus Schmalfuss, 2003 and Cylisticus rotundifrons (Schmalfuss, 1986), are expanded. Cylisticus masalicus sp. n. is described and its diagnostic characters are figured.


Introduction
established the subfamily Cylisticinae for the genus Cylisticus Schnitzler, 1853 in the family "Porcellionidae". Strouhal (1953) did not accept the recognition of Cylisticinae as a separate group and proposed the inclusion of all forms with five pairs of lungs in the subfamily Trachelipinae. Vandel (1962) followed Verhoeff's view and actually raised Cylisticidae to family level while Schmalfuss (2003a) questioned the validity of the family.
Members of Cylisticidae are characterized by: strongly convex body; exoantennal conglobation ability, though the head and telson are poorly adapted to conglobation; pereon tergite I without modifications or with grooves to receive the antennae; head with developed lateral and median lobes; supra-antennal line absent; antenna long; flagellum with two articles; pleopod exopodites I-V with wrinkled, partly covered, "Trachelipus-type", or with internal, covered, "Porcellio-type" lungs (Schmalfuss 1992(Schmalfuss , 2003aSchmidt 2003). There are no clear synapomorphies defining the taxon.
Cylisticidae species are distributed from central Europe to central Asia. According to the world catalogue of terrestrial isopods (Schmalfuss 2003b), the family comprises five genera, namely Cylisticoides Schmalfuss, 2003, Cylisticus Schnitzler, 1853, Lepinisticus Manicastri & Taiti, 1983, Parcylisticus Verhoeff, 1943, and Troglocylisticus Ferrara & Taiti, 1983. Schmalfuss (2003b included Cylisticoides in the family Cylisticidae with a question mark, since he believed that the superficial similarity of the genus Cylisticoides with the other genera might be due to convergence. Schmalfuss (1986) recorded the genus Cylisticus from Iran, based on three female specimens, as Cylisticus sp. I. In the same contribution, he also described Cylisticus rotundifrons which was later (Schmalfuss 2003a) transferred to the new genus Cylisticoides. He also named another female specimen as Cylisticus sp. II, which was later described as Cylisticoides angulatus (Schmalfuss 2003a).
In the present study, new records for Cylisticoides angulatus and C. rotundifrons in Iran are presented and Cylisticus masalicus sp. n. is described.

Material and methods
The material examined herein was collected in Iran ( Fig. 1), mostly from May 2014 to September 2015. The specimens were collected by hand and preserved in 96% ethanol. Drawings were made using a drawing tube on a Nikon Y-IDT compound microscope. Type material of the newly described species is deposited in the Zoological Museum, University of Tehran (ZUTC), the Iranian Research Institute of Plant Protection (IRIPP) and in the personal collection of the author (PCGMK).

Distribution. N Iran.
Remarks. Schmalfuss (1986) described Cylisticus rotundifrons from a female specimen collected at 12 km NE Zirab, Iran. He also named two females from Noor district as Cylisticus aff. rotundifrons. Schmalfuss (2003a) transferred the species to the genus Cylisticoides. In the present study, no male specimen was found either. Despite been relatively widely distributed in northern Iran ( Fig. 1), C. rotundifrons does not seem to be common. Though no male is known for the species, it can be readily distinguished from C. angulatus, the only congeneric species, from the rounded (vs. angled) postero-lateral margin of pereon-tergite I and the lack of a ridge on lateral margin of pereon-tergite I (present in C. angulatus). Based on current knowledge, C. rotundifrons is restricted to northern Iran. Distribution. SE Azerbaijan; N Iran. Remarks. Schmalfuss (2003a) established a new genus and species for specimens collected from southeastern Azerbaijan, namely Cylisticoides angulatus. He also assigned one female specimen collected from Dashte-Nazir, Iran, previously named as Cylisticus sp. II (Schmalfuss 1986), to this species.

Cylisticoides angulatus
In the present study, C. angulatus was collected at a broad range of localities in northern Iran (Fig. 1). The preferred habitat for this species seems to be the bark of decaying trees in old forests. Paratypes: same data as holotype, one male and two females (ZUTC 5787); same data as holotype, one male and one female (IRIPP Iso-1063); same data as holotype, three males and four females (PCGMK 1749); Gachsar to Marzanabad, 5 km to Dozdband, 36°16. Diagnosis. Cephalon with well developed quadrangular lateral lobes; median process pointed upwards; male pereopod VII ischium subrectangular; male pleopod endopodite I with apical part slightly bent outwards, bearing some setae.

Cylisticus masalicus
Description. Maximum length of both male and female, 15 mm. Color slaty gray with the usual pale muscle spots ( Fig. 2A, B). Exoantennal conglobation ( Fig. 2A) and body semi-circular in cross section. Cephalon with well developed quadrangular lateral lobes; median process pointed upwards, not surpassing lateral lobes in frontal view; vertex smooth, eyes with 20 to 22 ommatidia (Fig. 3A, B). Antenna long and slender, bent on the back when conglobating; fifth article of peduncle slightly longer than flagellum, with length:width ratio 7:1; flagellum with two articles of the same size (Fig. 3D).  Pereon smooth. Pereonite I with angular concavity on posterolateral margin. Noduli laterales on pereonite IV more than twice distant from the lateral margins than those on pereonite III (Fig. 3C).
Male: Pereopods I-VII merus and carpus with brushes of trifid setae, less dense in posterior ones (Fig. 3F-H). Pereopod VI ischium on sternal margin with three long spiny setae medially and three long spiny setae distally (Fig. 3G), pereopod VII ischium subrectangular, ventral side with a hairy brush of small setae, medially with six and distally with four long spiny setae (Fig. 3H). Pleopod endopodite I straight with apical part slightly bent outwards equipped with some short setae (Fig. 4A); exopodite I with rounded hind lobe, outer margin with a row of small setae (Fig. 4B, C). Pleopod endopodite II longer than exopodite; exopodite triangular with a line of setae on outer margin (Fig. 4D). Pleopod exopodites III-V as in Fig. 4E-G.
Etymology. The name of the species is after the type locality, the rain forests around Masal.
Distribution. N Iran.

Remarks.
In the examination of a collection of terrestrial isopods from northern Iran, Schmalfuss (1986) reported the genus Cylisticus for the first time based on three female specimens, which he cited as Cylisticus sp.I. This was the sole account for this genus up to now. In the present study, C. masalicus sp. n. is described. It has a broad distribution in the rain forests of the country (Fig. 5). According to the illustrations presented by Schmalfuss (1986) for the specimens named Cylisticus sp.I. and their collecting localities that lies inside the geographical range of the species (Fig. 5), those specimens presumably belong to C. masalicus as well.
Cylisticus masalicus sp. n. differs from other species of the genus by the straight apex of the male pleopod endopodite I which is also common in Parcylisticus species. The new species, however, is well assignable to the genus Cylisticus for its smooth body surface and short uropod exopodites. This species is similar to C. birsteini Borutzky, 1961 and C. iners Budde-Lund, 1880 but differs from the former in the shape of the male pleopod endopodite I, and from the latter in the position of noduli laterales and the shape of telson.