Antomicron intermedius Gagarin & Nguyen Vu Thanh, 2005

Holovachov, Oleksandr, 2012, Swedish Plectida (Nematoda). Part 2. The genus Antomicron Cobb, 1920, Zootaxa 3380, pp. 39-54 : 51-52

Antomicron intermedius Gagarin & Nguyen Vu Thanh, 2005

( Fig. 6 ; Table 2 )

Material examined. One male deposited in general collection of the Department of Invertebrate Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Specimen is somewhat flattened but still in good condition.

Habitat and locality. Cam River, Vietnam, 13 April 2003 (one male from the type locality).

Description. Male. Body tapering anteriorly in pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation, twisted ventrad in posterior part. Cuticle annulated; annuli 2.3 µm wide at mid-body, without ornamentation. Lateral field present, consists of single alae (two incisures), 2.1 µm wide at mid-body; originating at level of procorpus and extending to anterior 1/3rd of tail. Crystalloids absent. Prominent body pores in sublateral position at both sides of lateral field present, arising from oval lateral epidermal gland cells; three pairs of body pores are present along pharyngeal region; numerous body pores scattered over rest of the body. Sensilla associated with epidermal glands absent. Labial region bluntly rounded, continuous with body contour, lips fused. Anteriormost body annule, which demarcates labial region, located at level of middle of amphid. Inner and outer labial sensilla indistinct. Cephalic sensilla setiform, equal to 30% of labial region diameter. Subcephalic and cervical sensilla and ocelli absent. Amphidial fovea doughnut-shaped, 1.6 times as long as it is wide. Nerve ring surrounding pharynx at level of anterior part of isthmus. Hemizonid not seen. Secretory-excretory system present; renette cell large, located opposite to ventral side of cardia and anterior part of intestine, extends anteriorly along ventral side of pharynx and forms an excretory ampulla just posterior to nerve ring level. Excretory canal weakly cuticularised, extends from excretory ampulla for a short distance anteriorly and opens to the exterior via a pore just posterior to nerve ring. Buccal cavity uniformly tubular: cheilostom short funnel-shaped, undifferentiated; gymnostom undifferentiated; stegostom tubular, with uniformly thickened lumen. Pharynx muscular, cylindrical anteriorly, with distinct oval basal bulb; valvular apparatus absent. Anterior cylindrical part of pharynx subdivided by breaks in muscular pharyngeal tissue into cylindrical corpus (not visibly subdivided into pro- and metacorpus) and a narrow isthmus. Pharyngeal glands and their orifices indistinct. Cardia cylindrical, its posterior part embedded in intestine. Reproductive system diorchic; anterior testis outstretched; posterior one reflexed. Spicules paired, symmetrical, with weakly arcuate subcylindrical shaft and rectangular manubrium. Gubernaculum plate-like, with long dorsal apophysis. Accessory apparatus composed of one midventral precloacal papilliform sensillum located on anterior cloacal lip, nine midventral tubular supplements extending for 166 µm from cloaca towards anterior end, and 34 alveolar supplements extending anteriorly. Anteriormost alveolar supplement is located at level of cardia, 111 µm from anterior end. Posteriormost tubular supplement 34 µm anterior to cloaca, anterior to spicules. Sublateral precloacal and caudal sensilla present: two (one pair) precloacal setae at level of spicules and eight (four pairs) caudal setae arranged in two subventral and two subdorsal pairs. One pair of small papilliform sensilla is located just posterior to the second pair of subventral caudal setae. Tail elongate-conoid, gradually narrowing proximally. Unstriated tail tip swollen. Three caudal glands present, their nuclei are incaudal. Spinneret functional.

Diagnosis (with supplemental literature data). Antomicron intermedius is particularly characterised by the 0.7–1.0 mm long body; doughnut-shaped amphid; female without supplements; male without sensilla in pharyngeal region, with 5–9 tubular and 29–36 alveolar supplements, one pair of precloacal and four pairs of caudal setae, 21–31 µm long spicules.

Figures

FIGURE 6. Antomicron intermedius Gagarin & Nguyen Vu Thanh, 2005, male. A: Pharyngeal region, median section; B: Anterior end, surface view; C: Posterior region. Scale bar: A – C = 20 µm.