Pelodera teres ( Schneider, 1866 )

Tahseen, Qudsia, Akram, Mohd, Mustaqim, Malka & Ahlawat, Shikha, 2014, Descriptions of Pelodera scrofulata sp. nov. and Pelodera aligarhensis sp. nov. (Nematoda: Rhabditidae) with supplementary information on Pelodera teres (Schneider, 1866)., Journal of Natural History 48 (17), pp. 1027-1053 : 1050

Some observations on Pelodera teres ( Schneider, 1866)

( Figure 9 )

A few fixed specimens of P. teres described earlier by Hussain et al. (2006), were processed for scanning electron microscopy to observe labial details. Although the results were not particularly good, due to some debris adhering to the specimens, nevertheless some observations together with light microscope observations could be taken and the description summarized as follows.

The population of P. teres with 1:1 sex ratio, represented by ovoviviparous females with relatively wider lip region than males; low, apically compressed slightly offset lip region; heavily cuticularized inner labial margins; four to six fine bristles in each interlabial groove with the peripheral ones slightly longer than central ones; pharyngeal sleeve surrounding more than 50% of stoma; pharyngeal corpus moderately swollen, basal bulb with single-chambered haustrulum; intestinal cells compactly arranged at anterior and posterior extremities, intestinal lumen thick and refractive; reproductive system didelphic; large, conspicuous sphincter between spermatheca and uterus; males with dorsally reflexed testis; ejaculatory glands present; spicules massive with an indistinct neck; fused at distal end; bursa moderately developed, open peloderan with three pairs of precloacal genital papillae and six postcloacal pairs.

Pelodera has been considered a taxon with three monophyletic groups ( Sudhaus and Fitch 2001; Sudhaus 2011). Some of the important features present among these groups include: sexual dimorphism in the lip region (most species though more pronounced in the coarctata group); buccal cavity relatively wide, expanding posteriorly with heavily cuticularized telostegostom in the coarctata group; pharyngeal sleeve lacking in strongyloides group but present in the other two groups; pharyngeal corpus usually swollen (few exceptions in the males of the species showing sexual dimorphism); female reproductive system usually with a sphincter between the oviduct and uterus, spermatheca conspicuous; lining of intestine lumen thickened intestinal cells most compactly arranged anteriad and posteriad, the latter forming prerectum conspicuously seen in the strongyloides group; female tail conoid, cupolashaped to spicate; phasmid openings usually on the cupola part of tail or at 30–50% of tail length from anal opening in spicate tail; males with dorsally reflexed testis; ejaculatory glands often of unequal dimensions; spicules fused distally up to 70% of their length in strongyloides group and to lesser degrees in coarctata and teres groups respectively; bursa peloderan, anteriorly closed, sucker-shaped in coarctata group but anteriorly open in others; bursal velum smooth to striated or punctated; two pairs of precloacal genital papillae in all members of strongyloides group and in most species of the coarctata group with few exceptions whereas three pairs of precloacals present in members of teres group. Few members ( P. teres and P. pseudoteres ) in teres group are distinct from the rest in having markedly low, apically compressed lip region with heavily cuticularized inner labial margins and interlabial grooves bearing fine bristles.

Figures

Figure 9. Pelodera teres (Schneider, 1866). (A–E) Anterior end (A and B, scanning electron micrographs); (F) anterior pharyngeal region (lateral); (G) posterior pharyngeal region (lateral); (H) posterior intestinal region; (I) anterior genital branch; (J, K) uterine region with embryonating eggs; (L) vulval region (lateral); (M) vulval region (Ventral); (N) female posterior region (lateral); (O–Q) male posterior region (lateral) (Q is scanning electron micrograph); (R) male posterior region (ventral) (R is scanning electron micrograph). Scale bars: 10 μm.