Antomicron pratense Lorenzen, 1966

Holovachov, Oleksandr, 2012, Swedish Plectida (Nematoda). Part 2. The genus Antomicron Cobb, 1920, Zootaxa 3380, pp. 39-54 : 50-51

Antomicron pratense Lorenzen, 1966

( Fig. 5 ; Table 2 )

Material examined. Holotype male (slide # 196b) and paratype male (slide # 192) from the type collection of the Zoological Museum, University of Hamburg, Germany. Holotype male is somewhat flattened but still in good condition, paratype male is an aberrant individual and was not used in the description below.

Habitat and locality. Sediment from the Helgoländer Hallig (holotype male) and sediment from the Meldorfer Bucht (paratype male), German North Sea.

Description. Male. Body tapering anteriorly in pharyngeal region and posteriorly on tail; ventrally curved upon fixation, more strongly curved ventrad in posterior part. Cuticle annulated; annuli 2.8 µm wide at mid-body, without ornamentation. Lateral field present, consists of single alae (two incisures), 3.6 µm wide at mid-body; originating at base of amphid and extending posteriorly to middle of tail. Crystalloids absent. Prominent body pores in sublateral position at both sides of lateral field present, arising from oval lateral epidermal gland cells; six pairs of body pores are present along pharyngeal region, and one at level of cardia; 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 papilliform, equal to 5% of labial region diameter (described as “absent” in the original description). Subcephalic and cervical sensilla and ocelli absent. Amphidial fovea an inverted U-shaped, 2.8 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, obscure; excretory pore located just posterior to nerve ring. Buccal cavity uniformly tubular: cheilostom short funnel-shaped, undifferentiated; gymnostom short, with bar-shaped gymnorhabdia; 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 procorpus, cylindrical metacorpus and 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 strongly arcuate cylindrical shaft and elongate-ovoid manubrium. Gubernaculum plate-like, with long caudal apophysis. Accessory apparatus composed of one midventral precloacal papilliform sensillum located on anterior cloacal lip, three midventral tubular supplements extending for 81 µm from cloaca towards anterior end, and eight alveolar supplements extending anteriorly. Anteriormost alveolar supplement is located at level of cardia, 129 µm from anterior end. Posteriormost tubular supplement 23.5 µm anterior to cloaca, anterior to spicules. Sublateral precloacal and caudal sensilla present: two (one pair) precloacal papilla 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 pratense is particularly characterised by the 0.47–0.56 mm long body; inverted U-shaped amphid; male without sensilla in pharyngeal region, with three tubular and eight alveolar supplements, one pair of precloacal and four pairs of caudal setae, 14–27 µm long spicules.

Figures

FIGURE 5. Antomicron pratense Lorenzen, 1966, male. A: Pharyngeal region, median section; B: Anterior end, surface view; C: Posterior region. Scale bar: A – C = 20 µm.