Lubanema decraemerae, Morffe, Jans & Garcia, Nayla, 2013

Morffe, Jans & Garcia, Nayla, 2013, Two new genera of nematode (Oxyurida, Hystrignathidae) parasites of Passalidae (Coleoptera) from the Democratic Republic of Congo, ZooKeys 257, pp. 1-15 : 5-8

Lubanema decraemerae sp. n. Figs 4 A–G, 5 A–D

Type material.

♀ holotype, Democratic Republic of Congo, Kivu Region, Katale, 1°19'S, 29°22'E; in Didimus sp.; 4.V.1939; Hautmann coll.; CZACC 11.4667. Paratypes: ♀, same data as holotype, CZACC 11.4668; ♀, same data as holotype, RMCA.

Measurements.

Holotype (female) a = 6.70, b = 5.97, c = 40.18, V% = 57.92, total length = 2.210, maximum body width = 0.330, first cephalic annule ( length×width) = 0.020 × 0.070, stoma length = 0.048, procorpus length = 0.268, diameter of basal bulb = 0.108, total length of oesophagus = 0.370, excretory pore to anterior end = 0.520, vulva to posterior end = 0.930, anus to posterior end = 0.055, eggs = 0.168-0.173 × 0.075-0.080 (0.170 ± 0.004 × 0.078 ± 0.004 n = 2).

Paratypes (females) (n = 2) a = 4.44-6.36 (5.40 ± 1.36 n = 2), b = 3.66-5.68 (4.67 ± 1.43 n = 2), c = 34.45-38.18 (36.31 ± 2.64 n = 2), V% = 56.67 (n = 1), total length = 2.100-2.400 (2.250 ± 0.212 n = 2), maximum body width = 0.330 (n = 2), first cephalic annule ( length×width) = 0.020 × 0.063-0.065 (0.020 × 0.064 ± 0.002 n = 2), stoma length = 0.043-0.045 (0.044 ± 0.002 n = 2), procorpus length = 0.275-0.300 (0.288 ± 0.018 n = 2), diameter of basal bulb = 0.108 (n = 2), total length of oesophagus = 0.370-0.400 (0.385 ± 0.021 n = 2), nerve ring to anterior end = 0.223 (n = 1), excretory pore to anterior end = 0.410-0.600 (0.505 ± 0.134 n = 2), vulva to posterior end = 1.040 (n = 1), anus to posterior end = 0.043-0.055 (0.049 ± 0.009 n = 2), eggs = 0.183 × 0.078 (n = 1).

Description.

Female body large, notably robust and fusiform, widening gradually from the base of the first cephalic annule, reaching maximum width near mid-body, then tapering softly towards the posterior end that rounds off abruptly. A comparatively very short, conical tail appendage with its tip rounded arises terminally from the posterior end. Cervical cuticle unarmed, with marked annule (ca. 13 µm wide), extending to the rest of body, until level of the anus. Lateral alae thick, ca. 55 µm wide, extending from the hind third of the procorpus to the level of the anus. Posterior ends of lateral alae almost forming a straight angle with the body axis, slightly convex, their external margins forming a very short lobe. Head bearing eight rounded, paired papil lae, set-off from body by a single, deep groove. Amphids pore-like, laterally situated. Mouth trirradiate. First cephalic annule cone-like, slightly inflated, its margins convex, about two head-lengths long. Stoma long, about 1.5 first cephalic annule lengths long, surrounded by an oesophageal collar. Oesophagus consisting of a muscular, sub-cylindrical procorpus, its diameter little increased at its base. Isthmus as a constriction between the procorpus and the large, rounded, basal bulb. Valve plate well developed. Intestine simple, sub-rectilinear, its fore region very inflated. Rectum short. Anus sub-terminal. Nerve ring encircling procorpus at its posterior half (ca. 60% of its length). Excretory pore located at about the half of a body width behind the basal bulb. Vulva a median trasverse slit, displaced to the posterior half of body, lips less prominent. Vagina muscular, forwardly directed. Genital tract monodelphic-prodelphic. Ovary stout, reflexed at about one third of the body width behind the basal bulb. Oöcytes in a single row, about four times wider than long (ca. 8 × 2 µm). Eggs large, markedly ovoid, smooth-shelled. Male unknown.

Discussion.

The Malagasian genus Passalidophila resembles Lubanema gen. n. by having both the body robust and fusiform, cervical cuticle unarmed and markedly annulated, a similar form of the cephalic end, the lateral alae extending from the level of the procorpus to the anus and the tail short ( Van Waerebeke 1973). Differs by having a procorpus which diameter increases towards its joint with the isthmus. Lubanema gen. n. have a more cylindrical procorpus and the isthmus is absent. The tail of Passalidophila is subulate, instead of the current new genus, which presents a very short tail appendage arising from the rounded posterior end. In addition, the ovary of Passalidophila is slender vs. the robust ovary of Lubanema gen. n.

Other monogonant hystrignathid genera with smooth cervical cuticle are Christiella Travassos & Kloss, 1957; Coronocephalus Cordeira, 1981; Glaber Travassos & Kloss, 1958; Longior Travassos & Kloss, 1958; and Vulcanonema Travassos & Kloss, 1958. All of these taxa can be differentiated from Lubanema gen. n. by having a well developed tail, from attenuate to subulate. Christiella and Longior females have a comparatively slender body vs. the notably more robust and fusiform body of Lubanema gen. n. Also, both genera present cylindrical procorpus more elongate than in Lubanema gen. n.

Coronocephalus bears prominent, digitiform oral papillae, instead of the shorter, less developed papillae of Lubanema gen. n. In the latter genus the procorpus meets directly the basal bulb, while Coronocephalus present an isthmus. Glaber differs from Lubanema gen. n. by having the base of the procorpus clavate, instead of the sub-cylindrical procorpus present in the new genus.

Vulcanonema presents the cephalic end consisting of a narrow cephalic annule separated of the head by a conical region. In opposition, Lubanema gen. n. have the first cephalic annule just after the head. Also, the procorpus of Vulcanonema is sub-cylindrical, with a basal dilation, absent in the present new genus.

Lubanema gen. n. shows morphological affinities with the Australian genera Anuronema Clark, 1978 and Sprentia Clark, 1978 by having the cuticle unarmed and strongly annulated, reduction of the isthmus and the tail. Moreover, the lateral alae of Anuronema extends from the oesophageal region to almost the level of the anus, similar to Lubanema gen. n. The new genus differs from both by its genital tract monodelphic-prodelphic vs. didelphic-amphidelphic, procorpus sub-cylindrical vs. claviform and development of the lateral alae, which in Lubanema gen. n. are very wide and with lobes in the margins at their terminal ends.The procorpus is widely amalgamated with the basal bulb in Anuronema and Sprentia , whereas Lubanema gen. n. presents a well defined constriction separating both structures. Anuronema has a total reduction of the tail appendage ( Clark 1978) not observed in Lubanema with a short, conical tail.

Carlosia Travassos & Kloss, 1957 also presents a reduction of the isthmus, a large, slightly inflated first cephalic annule and marked annule in the cervical region ( Hunt 1982). It can be easily segregated from Lubanema gen. n. by having a didelphic-amphidelphic genital tract and the annule of the cervical cuticle retrorse, with posterior prolongations forming a double row of spines laterally situated.

Type host.

Didimus sp. ( Coleoptera : Passalidae ).

Site.

Hind gut, out of the caeca.

Type locality.

Katale, Kivu region, Democratic Republic of Congo.

Etymology.

Specific epithet dedicated to Prof. Dr. Wilfrieda Decraemer, from the Royal Belgian Institute of Natural Sciences. In appreciation for her help and support during the current research.