Eyualem Abebe

Aquatic nematodes from Ethiopia I : The genus Monhystera Bastian, 1865 (Monhysteridae: Nematoda) with the description of four new species

Freshwater bottom samples collected from Ethiopia during December 1993 and January 1994 yielded six species of the genus Monhystera Bastian, 1865 of which four are new to science.Each of the four new species can be recognized by a combination of characters; Monhystera shibrui n. sp. can be identified by the presence of a dorsal denticle, post-vulval gland cells, short vagina, and its viviparity, M. tanae n. sp. by the offset lip region, short cephalic setae, short vagina, possession of a pair of posterio-dorsolateral vaginal gland cells, more posteriorly situated vulva, lack of post-vulval gland cell, shorter vulva-anus distance compared to tail, its viviparity, short spicules, and short gubernaculum, M. nubiae n. sp. by its long vagina, presence of a pair of post-vulval gland cells and a very sharp, arrow-head shaped spinneret tip, and M. deleyi n. sp. can be recognized by the attenuated anterior end with narrow lip region, relatively wide amphids compared to corresponding body width, long vagina, presence of post-vulval gland cell, and cardia with three gland cells. Detailed descriptions of M. cf. gabaza Joubert & Heyns, 1980 and M. somereni Allgén, 1952 are also given. While both species are reported here for the first time from Ethiopia, the former is reported for the first time out of South Africa and the need for more information on its type population is stressed. Lateral line is reported here from two species, M. deleyi n. sp. and M. cf. gabaza Joubert & Heyns, 1980, for the first time in the genus. Scanning electromicrographs of four species, M. Shibrui n. sp., M. nubiae n. sp., M. deleyi n. sp. and M. cf. gabaza, are also given.Structures used in species identification in the genus Monhystera are reviewed. It is recommended, in future species descriptions in the genus, to use labial setae in addition to the use of cephalic setae, actual vaginal length in addition to its ratio to the corresponding body width both in females without and females with eggs but separately, a full and detailed description of the cells of the reproductive system and coelomocyte distribution, and to include an enlarged illustration of the spinneret outlet.

Aquatic nematodes from Ethiopia IV

Four species of the family Leptolaimidae Örley, 1880 sensu Lorenzen, 1981 one of which is new to science are described from Lake Tana and River Abbay, North-western Ethiopia. Anonchus coomansi n.sp. is identified by its smoothly truncate lip region, short (7–10µm long) and typically barrel-shaped stoma, didelphic females, and males with 22–28 ventro-median, tubular and 80–112 pouch-like, alveolar supplements. Detailed descriptions of Aphanolaimus tudoranceai Zullini, 1988, Paraphanolaimus behningi Micoletzky, 1923 and Paraplectonema pedunculatum (Hofmänner, 1913) Strand, 1934 are given. An attempt has been made to define the identity of P. behningi clearly. Ejaculatory glands are reported in the genus Anonchus here for the first time. Scanning electromicrographs of A. comansi n.sp. including that of its spicules, A.tudoranceai and P.behningi and a key to the species of Anonchus Cobb, 1913 are also presented.

Thalassomonhystera traesti n.sp., Eumonhystera andrassyi and three Monhystrella species (Monhysteridae: Nematoda) from Li River, China.

A new Thalassomonhystera species, i.e. T. traesti n.sp., and a new subspecies, Monhystrella lepidura chinensis n. subsp., together with Eumonhystera andrassyi (Biró, 1969) Andrássy, 1981, Monhystrella macrura (de Man, 1880) Andrássy, 1981 and Monhystrella iranica Schiemer, 1965 are described from Li River at Guiling, China. Thalassomonhystera traesti n.sp. is characterised by a combination of the following characters: expanded lip region, large and anteriorly situated amphids, prominent inner labial sensilla, and slender spicules and tube-like gubernaculum in males. Monhystrella lepidura chinensis n. subsp. belongs to Monhystrella lepidura (Andrássy, 1963) Andrássy, 1968 but differs from the three hitherto described subspecies in its possession of a pharynx that posteriorly expands into a double bulb. Monhystrella macrura, M. iranica and Eumonhystera andrassyiare reported here for the first time from China.

Aquatic nematodes from Ethiopia VIII; Enoplids, with descriptions of Brevitobrilus fesehai n.sp. and B. tsalolikhini n.sp. (Enoplida: Nematoda)

Two new and one known species of the genus Brevitobrilus, Epitobrilus setosus, Tripyla glomerans, and Ironus ignavus and I. sphincterus are described from sediments of LakesShala, Tana and Ziway, and River Abbay, Ethiopia. Brevitobrilus fesehai n. sp. can be recognized by acombination of characteristics: in having a narrowanterior end, short cephalic and outer labial setae,long and bow-shaped spicules, the posteriormostsupplement at a distance of less than a spicule lengthfrom cloacal opening, numerous micropapillae, andterminal and subterminal setae. B. tsalolikhinin.sp. can also easily be differentiated from allknown species in the genus in having a combination ofcharacteristics: long cephalic and outer labial setae,short spicules without median stiffening piece, theposteriormost supplement situated very close to thecloacal opening, supplements with straight duct thatmerges with the dorsal wall of the ampulla, andelongate spermatozoa. The remaining five species aredescribed in detail. Also scanning electronmicroscopic pictures of B. fesehai n.sp., B. tsalolikhini n.sp., Epitobrilus setosus andTripyla glomerans are presented.

Aquatic nematodes from Ethiopia II. The genus Monhystrella Cobb, 1918 (Monhysteridae: Nematoda) with the description of six new species.

Eight species of the genus Monhystrella, six of which are new to science, are described from bottom samples collected from three lakes, two rivers and a hot spring in Ethiopia. Monhystrella hoogewijsi n. sp. is identified by a distinctive bulge on the lip region, position of the amphids, offset and well developed single pharyngeal terminal bulb, tail shorter than vulva-anus distance, tail elongate-conoid for two-thirds of its length, and by the shape and size of the spinneret outlet; M. jacobsi n. sp. by its slender body, distinctively offset and distended lip region, indistinct and weakly expanding single terminal pharyngeal bulb, and shape and size of the tail and spinneret outlet; M. arsiensis n. sp. by its single terminal pharyngeal bulb, position of amphids, shape and length of tail and spinneret outlet; M. woitorum n. sp. by its hemispherical lip region, double terminal pharyngeal bulb, shape and length of the spinneret outlet, and shape and length of tail; M. ethiopica n. sp. by its bipartite stoma, size of amphid in relation to corresponding body width, filiform tail and shape and length of spinneret outlet. M. atteae n. sp. differs from all known Monhystrella species in having an inflated cap-like lip region and fine crystalloid bodies. M. macrura (de Man, 1880) Andrássy, 1981 and M. lepidura altherri (Juget, 1969) Jacobs, 1987 are reported from Ethiopia for the first time. Crystalloid bodies in the genus Monhystrella is reported here for the first time. Also the presence of a hyaline coelomocyte next to the germinal zone of the reproductive system is reported for the first time in the genus here in all eight species. The structures used in the taxonomy of the genus are reviewed.

Aquatic nematodes from Ethiopia IX. One new and three known species of Dorylaimidae, Mononchus truncatus Bastian, 1865, and Diploscapter coronatus (Cobb, 1893) Cobb, 1913 (Nematoda)

Laimydorus ritae n. sp., Laimydoruspseudostagnalis, Dorylaimus stagnalis, Ischiodorylaimus ugandanus, Mononchus truncatusand Diploscapter coronatus are described fromsediment samples of Lake Tana, Ethiopia. Laimydorus ritae n. sp. is identified by its shortodontostyle (16–18 µm), a value of 4 for the ratio’odontostyle L/lip region width‘, a lip region offsetby depression, an anteriorly situated longitudinalvulva, females with long tail (328–392 µm),non-hamate terminus and presence of males. Detaileddescriptions of the remaining five species withscanning electron microscopic pictures of L.pseudostagnalis are also provided. I. ugandanusis reported here for the first time out of its typelocality, Uganda.

Aquatic nematodes from Ethiopia, VII: the family Rhabdolaimidae Chitwood, 1951 sensu Lorenzen, 1981 (Chromadorida: Nematoda) with the description of Udonchus merhatibebi n.sp.

Three species of Rhabdolaimus de Man, 1880 and two (of which one is new to science) of Udonchus Cobb, 1913 are described from sediment samples of two lakes, two rivers and a hot spring, Ethiopia. Udonchus merhatibebi n.sp. is characterized by a distinctly truncate lip region and small cardia surrounded by gland cells that he on the anterior intestine at 45 °. The presence of twelve rugae in the cheilostome in the genus Udonchus is reported here for the first time. As a result, the family Rhabdolaimidae has been moved from suborder Leptolaimina to the superfamily Microlaimoidea in the suborder Chromadorina. The family Rhabdolaimidae is also subdivided into the subfamilies Rhabdolaiminae Chitwood, 1951 and Undonchinae n. subfam.. Scanning electronmicroscopic pictures of the five species viz. R. aquaticus de Man, 1880, R. cf. minor Cobb, 1914, R. terrestris de Man, 1880, U. merhatibebi n.sp. and U. tenuicaudatus Cobb, 1913 are also given.

A new species of Eumonhystera and three species of Monhystera (Monhysteridae: Nematoda) from Li River, China

A new Eumonhystera species, E. huruii n. sp., together with Monhystera nubiae Eyualem & Coomans, 1996, Monhystera somereni Allgén, 1952, and Monhystera wangi Wu & Hoeppli, 1932 are described from Li river at Guiling, China. Eumonhystera huruii n. sp. is closest to E. barbata Andrássy, 1981, but differs in having shorter anterior setae, much longer reproductive system, shorter and less dorsally bent tail and differently shaped spinneret. M. nubiae and M. wangi are reported here for the first time outside their type locality, whereas M. somereni is reported from China for the first time.

Aquatic nematodes from Ethiopia III : The genus Eumonhystera Andrássy, 1981 (Monhysteridae: Nematoda) with the description of E. geraerti n.sp.

Six species of the genus Eumonhystera, one of which is new to science, are described from bottom samples of Lake Tana and two associated rivers, River Abbay and R. Gelda, Ethiopia. E. geraerti n.sp. can be identified by being the only species in the genus that combines very posteriorly positioned vulva [V% = 68.2 ± 0.7 (67.3–69.3)] with very anteriorly positioned amphids (Amph-ABE/LRW = 0.8). The other five species encountered, E. dispar (Bastian, 1865) Andrássy, 1981, E. filiformis (Bastian, 1865) Andrássy, 1981, E. pseudobulbosa (von Daday, 1896) Andrássy, 1981, E. mwerazii (Meyl, 1957) Andrássy, 1981, and E. vulgaris (de Man, 1880), Andrássy, 1981, are described in detail. The identities of some of the already described populations of E. dispar, E. filiformis and E. vulgaris are questioned and clearer and better ways of defining each of these three species are suggested. A peritrophic-like membrane on the outer side of the brush-border of the intestine of E. mwerazii, a species reported here for the first time out of its type locality, is reported. Also, scanning electronmicrographs of sectioned and entire specimens of E. mwerazii are presented. All species are reported from Ethiopia for the first time.