Description of Crassolabium persicum sp. n. (Nematoda, Dorylaimida, Qudsianematidae), an interesting species from Iran

Abstract A new species of the genus Crassolabium, Crassolabium persicum sp. n., collected from Arasbaran rangelands of Iran, is described and illustrated. It is characterized by its body 1.92–2.40 mm long, lip region offset by constriction and 17–19 μm wide, odontostyle 16–19 μm long with aperture occupying less than one–third (27–30%) its length, neck 428–690 μm long, pharyngeal expansion 369–390 μm long or occupying 54–56% of total neck length, female genital system amphidelphic, uterus bipartite and 162–218 μm long or 2.3–3.5 times as long as body diameter, pars refringens vaginae well developed, V = 54–57.5, vulva longitudinal, prerectum bearing a blind sac, tail conical with rounded tip to conoid (25–36 μm, c=60–69, c’=0.5–0.9), spicules 68–72 μm long, precloacal pair of supplements far (22–27 μm) from cloacal aperture, and 13–17 shortly spaced ventromedian supplements with hiatus. The new taxon is compared in depth to its relatives in Crassolabium as well as other similar species of Aporcelaimellus and Amblydorylaimus.


Introduction
The genus Crassolabium Yeates, 1967(syn. Thonus Thorne, 1974) is a highly diverse and worldwide distributed dorylaimid taxon. According to the recent compendium provided by Peña-Santiago and Ciobanu (2011), it includes 33 valid species known to occur in 47 countries, islands and archipelagos. It is a rather heterogeneous nematode group, whose differentiation from the genera Aporcelaimellus Heyns, 1965(syn. Takamangai Yeates, 1967 and Labronema Thorne, 1939 is occasionally intricate. The dorylaimid fauna of Iran has not traditionally received much attention. This situation has significantly changed during recent years, when a series of contributionssee, for instance, Pedram et al. (2011) and the references cited therein -have revealed it is rich in species, many of them previously unknown. Concerning presence of the genus Crassolabium, in Iran, Mowlavi et al. (2012) very recently reported the presence of C. rhopalocercum (de Man, 1876) Peña-Santiago and Ciobanu 2008, but there is no other available information.
During a general nematological survey in natural and cultivated areas, a few female and male specimens belonging to this genus were collected. Its study revealed this material belongs to a non-described and interesting species, which is the matter of this contribution.

Material and methods
Soil samples were collected from Mahmood Abad, Arasbaran rangelands, northwest Iran, during 2009-2010. The nematodes were extracted by a modified combined sieving and centrifugation flotation method (Jenkins 1964), processed to anhydrous glycerine following De Grisse's (1969) technique, and mounted on permanent glass slides for handling. Morphometric data were obtained using a drawing tube attached to an Olympus BX 41 light microscope. Morphometrics included de Man's indices and other measurements traditionally diagnostic for the group. Some of the best-preserved specimens were photographed with a Nikon Eclipse 80i microscope and a Nikon DS digital camera. Raw photographs were edited using Adobe® Pho-toshop® CS. Drawings were made using a camera lucida attached to Nikon Eclipse 80i microscope. taxonomy Crassolabium persicum sp. n. urn:lsid:zoobank.org:act:E8DCBD3A-1F12-4390-98C4-F2AFCA0A1CF9 http://species-id.net/wiki/Crassolabium_persicum Figures 1, 2 Material examined. Five females and four males, in excellent state of preservation.
Female. Genital system didelphic-amphidelphic, with both branches well and equally developed, the anterior 364-476 μm long or 15-18% of total body length, and the posterior 358-395 μm long or 14-16% of total body length. Ovaries reflexed, moderately developed, sometimes reaching and surpassing the sphincter level; the anterior 114-131 μm, the posterior 101-127 μm long; oocytes arranged distally in several rows and then proximally in a single row. Oviduct joining ovary, 88-130 μm long or 1.3-1.8 body diameters and consisting of a tubular part and a moderately developed pars dilatata with small lumen. Oviduct-uterus junction marked by a distinct sphincter. Uterus 162-218 μm long or 2.3-3.5 times the corresponding body diameter, bipartite, i.e., consisting of two sections with variable length: a wider proximal region with distinct lumen containing abundant sperm cells, and a distal part with narrow lumen and globular walls surrounded by circular muscles. Vagina extending inwards 32-45 μm or less than half (36-44%) of the corresponding body diameter; pars proximalis longer than wide, 26-40 × 19-22 μm, with slightly sigmoid walls and surrounded by moderately developed musculature; pars refringens with (in lateral view) two distinct, trapezoidal, closely-spaced pieces, measuring 6-8 × 8-11 μm and with a combined width of 17-21 μm; pars distalis very short, with two small sclerotizations close to the pars refringens. Vulva a post-equatorial longitudinal slit appearing in lateral view as a short longitudinal depression. Prerectum 1.3-2.1 anal body diameters long, with a well developed blind sac. Rectum 0.9-1.3 times the anal body diameter. Tail short, conical with rounded tip to conoid, ventrally nearly straight, dorsally more convex. Two pairs of caudal pores, one subdorsal, other lateral or subventral.
Male. Genital system diorchic, with opposite testes. In addition to the adcloacal pair, situated at 22-27 μm from cloacal aperture, there is a series of 13-17 shortly and regularly spaced (11-16 μm apart) ventromedian supplements, outside the range of spicules; posterior-most ventromedian supplement located at 47-53 μm from adcloacal pair. Spicules strongly curved ventrad and moderately robust, 4.0-5.0 times as long as wide and 1.6-1.7 anal body diameter long. Lateral guiding pieces short and robust, 11-16 μm long, 2.5-4.0 times as long as wide, with   bifurcate terminus in which the posterior arm is visibly longer than the anterior one. Prerectum length 1.7-2.3 times the anal body diameter. Tail somewhat more conoid than that of female.
The new species is also comparable to Aporcelaimellus index (Thorne, 1939) Andrássy 1986, in its general morphology and morphometry as well as the peculiar shape of lateral guiding pieces being short, robust and with bifurcate terminus in which the posterior arm is visibly longer than the anterior one, forming digitations, hence the specific name index as stated by Thorne (1939). Aporcelaimellus index is a very atypical member of Aporcelaimellus Heyns, 1965 because the odontostyle aperture is distinctly shorter than half its total length, making its identity questionable, and indicating further studies for its elucidation. It was originally described on the base of only one male specimen from Utah (U.S.A.), and later reported, also with only one male specimen, from Mongolia by Andrássy (1964). The new species herein described differs from A. index in the position of the pre-cloacal pair of male genital papillae (vs closer to cloacal aperture) and in the number (vs 25-27) and arrangement (vs contiguous) of ventromedian supplements.
Finally, in the location of the pre-cloacal pair of male genital papillae -comparatively far from cloacal aperture, indeed a very unusual feature in dorylaims -the new species is reminiscent of the genus Amblydorylaimus Andrássy, 1998, with the type and only species A. isokaryon (Loof, 1975) Andrássy 1998, but it differs from this in the nature of odontostyle (vs weakly sclerotized and longer, 31-35 μm long), S 1 N much smaller than DN and S 2 N (vs equally sized all of them), and hiatus present (vs absent).
Type material. Female holotype, two female paratypes and three male paratypes are deposited in Nematode Collection, Faculty of Agriculture, University of Tabriz, Tabriz, Iran. One female paratype and one male paratype with nematode collection of Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Spain.
Etymology. The specific epithet refers to the geographical area where the new species was collected from.