Description of Panagrellus ulmi sp. n. (Rhabditida, Panagrolaimidae) from Iran, and comments on the species of the genus and its relatives Author Abolafia, Joaquín Author Alizadeh, Mehrdad Author Khakvar, Reza text Zootaxa 2016 4162 2 245 267 journal article 10.11646/zootaxa.4162.2.3 b4e985a5-6f89-4e11-8d9a-35d9cae9d03d 1175-5326 256155 91F2C451-FE89-483C-AEFA-2F33974C60D2 Panagrellus ulmi sp. n. ( Figs 1‒3 ) Material examined. Eleven females and ten males in good condition. Type locality and habitat. The species was collected inside wetwood cankers caused by Lelliottia nimipressuralis (Carter) (Enterobacteriaceae) on Ulmus glabra Hudson from the Bahman Boulevard , Tabriz , province of East Azerbaijan ( Iran ), at 1449 m altitude ( 38º 03' 43'' N ; 46º 19' 48'' E ). Type material. Eight females ( holotype and paratypes ) and seven males ( paratypes ) deposited in Departamento de Biología Animal , Biología Vegetal y Ecología, Universidad de Jaén , Spain ; two females and two males ( paratypes ) deposited in Department of Plant Protection, University of Tabriz, 29 Bahman Blvd, Tabriz, Iran ; and one female and one male ( paratypes ) deposited in the nematode collection of the Swedish Museum of Natural History, Stockholm ( Sweden ) . Morphometrics. Listed in Table 1 . Description . Adult: Nematodes of small size, 0.91‒1.22 mm long in females and 0.82‒1.18 mm long in males. Body cylindrical, tapering towards both ends. Habitus slightly ventrally curved after fixation. Cuticle with scarcely visible transverse striations or annuli, about 1 µm wide at mid-body. Lateral field with two wings or alae seen as three longitudinal incisures at mid-body, inconspicuous under LM. Lip region low, narrowing to distal end, with six small lips, more or less rounded, and oral opening surrounded by six acute liplets; six labial papillae located at the base of oral liplets and four cephalic papillae located at base of dorsal and ventral lips. Amphid openings small, slit-like, located at base of the lateral lips. Stoma panagrolaimoid; cheilostom without refractive rhabdia; gymnostom shorter than cheilostom, with straight refractive rhabdia; stegostom as long as cheilo-gymnostom, having funnel-shaped lumen in lateral view and walls with non-refractive rhabdia. Pharynx panagrolaimoid; pharyngeal corpus almost cylindrical with metacorpus not swollen; isthmus slender, 2.2‒2.8 times the corpus length; basal bulb ovoid, with valvular apparatus. Cardia conoid, surrounded by intestinal tissue. Intestine lacking distinct specialization, but a cardiac portion is differentiated at its anterior part slightly longer than the corresponding body width, with thinner walls. Nerve ring and hemizonid at 63‒74% of neck length, the former surrounding the anterior part of the isthmus. Excretory pore at 52‒68% of neck length, at level of metacorpus, difficult to observe in the most of specimens. Deirid not visible. Female: Reproductive system mono-prodelphic, located at right side of intestine; ovary very long without flexures, sometimes reaching the posterior part of the intestine; oocytes initially in two rows and posteriorly in only one; oviduct with thick walls, as long as the corresponding body diameter; uteri with very thin walls, 5.5‒11.2 times the corresponding body diameter long; uterine eggs usually present in different stages of development, frequently with well-developed juveniles; postvulval uterine sac long, 2.0‒3.4 times the corresponding body diameter, swollen and connected to the vagina by a short tubular part; vagina extending inwards obliquely 21‒41% of body diameter, surrounded by strong musculature. Vulva-anus distance 1.5‒2.1 times the tail length or 3.9‒6.6 times the corresponding body diameter. Rectum 1.0‒2.2 times as long as anal body diameter, with three glands. Tail elongate-conoid, narrower in posterior half. Phasmid at 34‒46% of tail length. TABLE 1. Measurements (in µm) of Panagrellus ulmi sp. n.

Locality	Tabriz
Province	East Azerbaijan
Habitat	Wetwood canker on elm tree
n	♀ Holotype 10♀♀ Paratypes	10♂♂ Paratypes
Body length	1137 1050.5 ± 101.6 (906‒1217)	1001.7 ± 136.2 (817‒1183)
a	18.3 28.1 ± 1.5 (25.9‒30.3)	29.2 ± 3.0 (25.0‒34.9)
b	4.6 4.8 ± 0.5 (4.3‒5.7)	4.9 ± 0.6 (4.0‒5.7)
c	8.5 8.3 ± 0.6 (7.4‒9.4)	9.6 ± 0.9 (8.1‒11.2)
c'	6.4 5.5 ± 0.7 (4.5‒6.5)	4.1 ± 0.5 (3.3‒4.9)
V	67 66 ± 1 (64‒68)	-
Lip region width	11 10.2 ± 0.8 (9‒12)	9.4 ± 2.1 (6‒11)
Stoma length	13 11.5 ± 0.7 (10‒12)	11.0 ± 0.7 (10‒12)
Stoma width	4 3.7 ± 0.5 (3‒4)	3.5 ± 0.5 (3‒4)
Pharyngeal corpus	143 126.5 ± 9.3 (115‒140)	118.0 ± 10.7 (102‒134)
Isthmus	60 51.7 ± 3.2 (46‒56)	47.9 ± 3.9 (42‒56)
Bulbus	30 28.7 ± 2.1 (24‒32)	26.7 ± 2.8 (22‒30)
Pharynx length	233 206.9 ± 11.0 (191‒222)	192.6 ± 15.7 (166‒220)
Nerve ring - anterior end	162 147.9 ± 8.6 (132‒162)	140.9 ± 10.9 (122‒160)
Excretory pore - anterior end	108 120.3 ± 3.2 (118‒124)	120.4 ± 14.2 (100‒140)
Neck length	246 218.4 ± 11.2 (203‒234)	203.6 ± 16.0 (176‒231)
Annuli	1 1.0 ± 0.0 (1)	1.0 ± 0.0 (1)
Cuticle at midbody	1 1.0 ± 0.0 (1)	1.0 ± 0.0 (1)
Body diameter at neck base	35 34.9 ± 1.9 (32‒38)	31.4 ± 2.6 (28‒35)
Body diameter at midbody	39 37.4 ± 3.4 (34‒45)	34.6 ± 5.6 (28‒44)
Lateral field width	4 5 (n=1)	7.0 ± 1.4 (6‒8)
Anterior ovary/testis length	400 558.8 ± 120.1 (361‒744)	168.1 ± 47.2 (97‒224)
Anterior oviduct length	60 70.2 ± 18.2 (47‒100)	-
Anterior uterus length	342 339.7 ± 87.5 (232‒490)	-
Anterior genital branch	402 409.9 ± 99.8 (293‒590)	575.8 ± 145.5 (387‒787)
Postvulvar sac	108 101.4 ± 24.7 (67‒154)	-
Uterine egg length	44 41.0 ± 4.5 (37‒47)	-
Uterine egg width	28 25.8 ± 5.3 (18‒30)	-
Vagina length	13 12.8 ± 1.3 (12‒15)	-
Vulva - anterior end	760 694.8 ± 75.8 (577‒811)	-
Rectum length	30 27.3 ± 4.5 (23‒39)	8.6 ± 1.0 (8‒11)
Anal body diameter	21 23.0 ± 2.8 (18‒26)	25.9 ± 3.8 (21‒31)
Tail length	134 126.2 ± 10.6 (112‒144)	105.3 ± 15.8 (76‒124)
Phasmid - anus distance	56 49.1 ± 5.1 (39‒56)	45.8 ± 7.2 (32‒55)
Spicules length	- -	27.5 ± 2.5 (24‒32)
Gubernaculum length	- -	14.0 ± 1.4 (12‒17)

FIGURE 1. Panagrellus ulmi sp. n. A: Neck. B: Anterior end. C: Lateral field. D: Female genital system. E: Female entire. F: Male entire. G–I: Spicule. J–L: Gubernaculum. M: Female posterior end. N: Male posterior end. O: Vulva in ventral view. FIGURE 2. Panagrellus ulmi sp. n. (light microscope micrographs). A: Neck (arrows pointing the excretory pore). B, F: Anterior end at liplets and stoma levels, respectively. C: Female reproductive system. D: Oviduct. E: Testis. G: Vulva (ventral view). H: Vagina region. I: Isthmus (arrows pointing the excretory pore). J: Female posterior end (arrow indicates the phasmid). K: Male posterior end (arrows pointing some genital papillae). L: Spicule and gubernaculum. FIGURE 3. Panagrellus ulmi sp. n. (female, scanning electron microscope micrographs). A: Body anterior end. B–E: Lip region in frontal (dorso-ventral position), right subventral (subfrontal), ventral and left sublateral views, respectively. F: Lateral field. G–H: Tail in lateral and ventral views, respectively. FIGURE 4. Anterior end (up), spicule and gubernaculum (down) of Panagrellus species (A–N) and Baujardia (O). A: P. ceylonensis . B: P. dorsobidentatus . C: P. dubius . D: P. filiformis . E: P. japonicus . F: P. leperisini . G: P. ludwigi . H: P. nepenthicola . I: P. pycnus . J: P. redivivoides . K: P. redivivus (cf. de Man, 1914). L: P. silusioides . M: P. ulmi sp. n. N: P. ventrodentatus . O: B. mirabilis . All drawings based on the original descriptions except where indicated (not to scale). FIGURE 5. Anterior end (up), spicule and gubernaculum (down) of Panagrobelus species (A–E) and Plectonchus (F–O). A: P. coronatus . B: P. hunti . C: P. incisus . D: P. phloeosini . E: P. stammeri (cf. Stock et al. , 2002). F: P. ateri . G: P. cuniculari . H: P. extrematus . I: P. galeatus . J: P. ligniperdae . K: P. longevulvus . L: P. molgos . M: P. procerus . N: P. sucicola . O: P. wyganti . All drawings based on the original descriptions except where indicated (not to scale). Male: Reproductive system monorchic with ventrally reflexed testis. Tail elongate-conoid, narrower at its posterior third. Spicules curved ventrad, with manubrium rounded or ventrally hook-shaped, calamus very short and lamina ventrally bent with dorsal anterior hump, fork-like bifurcate tip and ventral wing. Gubernaculum ventrally bent, showing an anterior dorsal handle-like manubrium. Genital papillae arranged in two precloacal pairs, one adcloacal pair and five postcloacal pairs: two mid-subventral (sv1 and sv2), one subventral terminal (sv3), one mid-subdorsal (sd1) and one subdorsal terminal (sd2). Phasmid at 39‒46% of tail length, close to the terminal papillae. Diagnosis. Panagrellus ulmi sp. n. is characterized by its small size ( 0.91‒1.22 mm long in females and 0.82‒1.18 mm long in males), lateral field with three longitudinal incisures, lip region narrowing to distal end with six small lips and oral opening surrounded by six acute liplets, stoma with gymnostom shorter than cheilostom, cheilorhabdia not refrigent, gymnorhabdia refrigent, pharynx with metacorpus not swollen and isthmus slender, excretory pore at level of metacorpus, ovary very long without flexures, oviduct swollen, postvulval uterine sac long, 2.0‒3.4 times the corresponding body diameter, female and male tails elongate-conoid, spicules with rounded and ventrally bent manubrium and lamina with dorsal anterior hump and fork-like bifurcate tip, gubernaculum with anterior dorsal handle-like manubrium, postcloacal genital papillae five pairs, two anterior subventral, one anterior subdorsal at same level than the first subventral, one posterior subventral and one posterior subdorsal both at same level. Relationships. The new species resembles other species having slender spicules with bifurcate tips, including P. ceylonensis Hechler, 1971 , P. dubius Sanwal, 1960 , P. leperisini Massey, 1974 , P. nepenthicola ( Menzel, 1922 ) Goodey, 1945 , P. redivivoides ( Goodey, 1943 ) Goodey, 1945 , P. redivivus ( Linné, 1767 ) Goodey, 1945 and P. silusioides Tsalolikhin, 1965 . It can be differentiated from all of these by its narrower lip region with liplets ( vs wider with rounded lips lacking liplets). It can also be distinguished from P. ceylonensis by having a more anterior excretory pore position (at 52‒58% of neck length or at metacorpus level vs at 93% or at bulbus), shorter spicules (24‒32 µm long with large bifurcation at tip vs 87‒95 µm long with small bifurcation) and gubernaculum (12‒17 µm long vs 30‒34 µm long). From P. dubius by having a more anterior excretory pore position ( vs at 60‒68% or at bulbus level), longer female tail (112‒144 µm, c’= 4.5‒6.5 vs 87 µm, c’= 3.4), smaller spicules (24‒32 µm vs 39‒45 µm) and gubernaculum (12‒17 µm vs 25‒36 µm). From P. leperisini by the more anterior position of the excretory pore (at 78% or at isthmus level), longer isthmus (corpus 2.2‒2.8 times the isthmus length vs 4.7 times), shorter spicules ( vs 58 µm) and gubernaculum ( vs 28 µm). From P. nepenthicola by its small body length (0.91‒1.22 vs 2.00‒2.88 µm in females and 0.82‒1.18 vs 1.36‒1.87 µm in males), slighly more anterior vulva position (V= 64‒68 vs 71‒77), smaller spicules ( vs 59‒71 µm). From P. pycnus by having more anterior vulva position ( vs 71‒77), different arrangement of genital papillae (sv1 and sv2 separate from each other and sd1 at same level than sv1 vs sv1 and sv2 together and sd1 more posterior), shorter spicules ( vs 50‒70 µm and with small bifurcation at tip) and gubernaculum ( vs 25‒27 µm). From P. redivivoides , the most similar species, by having longer isthmus (2.2‒2.8 times the isthmus length vs corpus 4.0‒10.4 times), spicules with large bifurcation ( vs small) and different arrangement of genital papillae ( vs sv1 and sv2 very close and sd1 posterior to sv2). From P. redivivus by its more anterior excretory pore position ( vs at 73‒90% or at posterior part of isthmus), shorter male tail (76‒124 µm vs 100‒154 µm), shorter spicules ( vs 36‒70 µm) and gubernaculum (18‒32 µm). From P. silusioides by its small body length ( vs 2.20‒2.60 µm in females and 1.70‒2.10 µm in males), more anterior position of excretory pore ( vs at 77% or at isthmus level). Etymology. The specific epithet references the tree where the nematode was found. Comments on the genus Panagrellus and its relatives. The genus Panagrellus Thorne, 1938 is a homogeneous taxon ( Fig. 4 A‒N, Table 2 ) characterized by having a short gymnostom, long postvulval sac [ P. pycnus was initially described by Thorne (1938) as lacking a postvulval sac but re-examination of the type material by Hechler (1971a) showed that it does have a postvulval sac although it was not illustrated] and spicules with bifurcate tip (see Stock & Nadler 2006). Most of the species present slender ventrally curved spicules with rounded or hook-like manubrium; only three species [ P. dorsobidentatus ( Rühm, 1956 ) Baker, 1962 , P. ludwigi (de Man, 1910 ) Goodey, 1945 and P. ventrodentatus ( Heindl-Mengert 1956 ) Baker, 1962 ] have robust, scarcely ventrally curved spicules with truncate manubrium. This genus shows morphological similarities with the genus Baujardia Bert, Tandingan De Ley, van Driessche, Segers & De Ley, 2003 ( Fig. 4 O), mainly in the morphology of the postvulval sac (almost identical with the species examined here), spicule and gubernaculum morphology (especially those of P. ventrodentatus ). This close relationship is also supported by molecular analysis (see phylogenetic tree in Bert et al. , 2003 ). For this monotypic genus, Andrássy (2005) erected the subfamily Baujardinae based on the presence of lip region with cephalic setae and the slightly different structure of the stoma (longer and bearing denticles). However, these characters are not enough to maintain it separate from the subfamily Panagrellinae Andrássy, 1976 . Accordingly, we propose Baujardinae as a junior synonym of Panagrellinae. On the other hand, the morphology of the spicule with bifurcate tip, frequent in Panagrellus , appears also in other species not belonging to this genus, as in Plectonchus hunti Stock, De Ley, De Ley, Mundo-Ocampo, Baldwin & Nadler, 2002 . In fact, this species presents numerous characters disagreeing with the rest of the species included in the genus Plectonchus Fuchs, 1930 , such as a shorter gymnostom than cheilostom ( vs longer), more anterior vulva position (at 53‒77% of the body length vs more posterior, at 66‒80%, close to anus), offset sac-like spermatheca ( vs not offset or absent), very short postvulval sac (one third of the corresponding body diameter vs absent), female and male tails plump conoid with acute mucro ( vs conoid to conoid elongate, posteriorly constricted), spicules almost straight with lamina having slightly bifurcate tip ( vs bent spicule with acute tip) and gubernaculum almost straight ( vs slightly sigmoid). These differences suggest that this species does not belong to the genus Plectonchus . Although the morphology of the spicules, with slightly bifurcate tip, agrees with what is seen in Panagrellus , differences such as the presence of an offset sac-like spermatheca ( vs not offset), postvulval sac length (very short, less than a half of the corresponding body diameter vs very long, ca 3 times its width), and in tail morphology (plump conoid vs elongate in both sexes) suggest otherwise. Alternatively, most of the morphological features agree well with those of species of the genus Panagrobelus Thorne, 1939 ( Fig. 5 A‒E, Table 3), only differing in the lip morphology (lips grouped in pairs with secondary axils slightly expanded to oral opening vs lips with primary and secondary axils expanded in flap-like processes, the secondary ones larger). As can be observed, the morphology of P. hunti is intermediate between Panagrellus and Panagrobelus , while molecular analyses (see Nadler et al. 2006, Stock & Nadler, 2006) show that P. hunti is more related to Panagrobelus ( P. stammeri ) than to any studied Panagrellus species. Because of this, there do not appear to be enough differences to propose a new genus only for this species and we transfer it to the genus Panagrobelus as P. hunti ( Stock, De Ley, De Ley, Mundo-Ocampo, Baldwin & Nadler, 2002 ) n. comb. The lip region of this species could be a plesiomorphic character state, where the small secondary axil process is homologous with the flap-like process (apomorphic) present in other species of Panagrobelus . On the other hand, the genus Plectonchus ( Fig. 5 F‒O, Table 4 ) contains, after removing P. hunti , species mainly with large gymnostom, post-equatorial vulva (V= 66‒81), spicules with rounded manubrium and anteriorly bent lamina, and usually robust and sigmoid gubernaculum. The lip region, however, shows great variation. Agreeing with this pattern is Anguilluloides procerus ( Weingärtner, 1953 ) Rühm, 1956 ( Fig. 5 M), the only species of the genus Anguilluloides Rühm, 1956 , distinguished from some species of the genus Plectonchus only by having a shorter gymnostom (see Andrássy 1984 ). This character state is also present in such Plectonchus species as P. cuniculari Fuchs, 1930 and P. longevulvus Khan, Hussain & Tahseen, 2012 . For this reason, we consider there are not enough differences between these genera to maintain them as separate taxa, and we consider Anguilluloides a junior synonym of Plectonchus , and suggest that its only species be renamed as Plectonchus procerus ( Weingärtner, 1953 ) n. comb. Diagnosis of Panagrellus (emended). Panagrolaimidae, Panagrellinae. Body slightly curved ventrally after fixation. Cuticle with fine annulations. Lateral field with two longitudinal wings. Lip region with six low lips, slightly separated and grouped in pairs, with primary and secondary axils similar in morphology. Amphids slit-like. Stoma with wide cheilo-gymnostom, cheilostom longer than gymnostom, only cheilostom with refringent rhabdia; stegostom variable in length, having narrow lumen. Pharyngeal corpus subcylindrical, without demarcation between pro- and metacorpus, not or only scarcely swollen; isthmus usually long and narrow; basal bulb rounded or pyriform with distinct valvular apparatus. Nerve ring encircling the isthmus. Excretory pore located anterior or posterior to nerve ring. Female reproductive system mono-prodelphic; ovary anterior to vulva, posteriorly reflexed and extending slightly past the vulva, sometimes reaching the rectum. Offset spermatheca absent. Post-vulval sac long, about 2 to 3.5 times the corresponding body diameter long. Vagina long, straight or slightly oblique, strongly muscular. Vulva slightly post-equatorial, rarely more posterior (V=53‒82), protruding, with the anterior lip slightly larger than the posterior. Female tail conoid elongate, ca 3‒7 times the anal body diameter with acute tip. Phasmids located at middle of tail. Male reproductive system monorchic; testis reflexed posteriorly. Male tail conoid, slightly ventrad curved, with narrower part after last papillae. Genital papillae three precloacal pairs, two subventral and one sublateral, four or five postcloacal pairs, and a single ventral papilla. Spicules paired and symmetrical, with rounded ventral bent manubrium, frequently hook-like, lamina with bifurcate tip and ventral velum present but inconspicuous. Gubernaculum slightly ventral curved. List of species. The genus Panagrellus currently includes 14 species (see Table 2 ): Type species: P. redivivus ( Linné, 1767 ) Goodey, 1945 syn. Chaos redivivus Linné, 1767 syn. Anguillula rediviva ( Linné, 1767 ) Stiles & Hassal, 1905 syn. Turbatrix redivivus ( Linné, 1767 ) Peters, 1927 syn. Turbator redivivus ( Linné, 1767 ) Goodey, 1943 syn. Vibrio anguillula Müller, 1773 syn. Vibrio glutinus Müller, 1783 syn. Vibrio anguillula glutinus Müller, 1783 syn. Gordius glutinus ( Müller, 1783 ) Oken, 1815 syn. Anguillula glutina ( Müller, 1783 ) Ehrenberg, 1838 syn. Rhabditis glutina ( Müller, 1783 ) Dujardin, 1845 syn. Anguillula silusiae de Man, 1913 syn. Turbatrix silusiae (de Man, 1913 ) Peters, 1927 syn. Turbator siusiae (de Man, 1913 ) Goodey, 1943 syn. Panagrellus silusiae (de Man, 1913 ) Goodey, 1945 syn. Neocephalobus leucocephalus Steiner, 1936 syn. Turbator leucocephalus ( Steiner, 1936 ) Goodey, 1943 syn. Panagrellus leucocephalus ( Steiner, 1936 ) Goodey 1945 syn. Cephalobus parasiticus Sandground, 1939 Other species: P. ceylonensis Hechler, 1971 P. dorsobidentatus ( Rühm, 1956 ) Baker, 1962 syn. Anguillula dorsobidentata Rühm, 1956 P. dubius Sanwal, 1960 P. filiformis ( Sukul, 1971 ) Andrássy, 1984 syn. Tylorhabdus filiformis Sukul, 1971 P. japonicus ( Yokoo & Ota, 1961 ) Andrássy, 1984 syn. Brevibucca japonica Yokoo & Ota, 1961 P. leperisini Massey, 1974 P. ludwigi (de Man, 1910 ) Goodey, 1945 (name corrected by Andrássy 2005 ) syn. Anguillula ludwigii de Man, 1910 syn. Turbatrix ludwigii (de Man, 1910 ) Peters, 1927 syn. Turbator ludwigi (de Man, 1910 ) Goodey, 1943 P. nepenthicola ( Menzel, 1922 ) Goodey, 1945 syn. Anguillula nepenthicola Menzel, 1922 syn. Turbator nepenthicola ( Menzel, 1922 ) Goodey, 1943 P. pycnus Thorne, 1938 P. redivivoides ( Goodey, 1943 ) Goodey, 1945 syn. Turbator redivivoides Goodey, 1943 syn. Anguillula redivivoides ( Goodey, 1943 ) Rühm, 1956 syn. Anguillula zymosiphila Brunold, 1950 syn. Panagrellus zymosiphilus ( Brunold, 1950 ) Goodey, 1945 P. silusioides Tsalolikhin, 1965 P. ulmi sp. n. P. ventrodentatus ( Heindl-Mengert, 1956 ) Baker, 1962 syn. Anguillula ventrodentata Heindl-Mengert, 1956 TABLE 2 . Morphometrics (in µm) of Panagrellus species. Species sex L a b c c̕ V Stoma Excretory pore/neck length lenght (%) or position ceylonensis 10♀♀ 1057—1530 24.0 (n=1) 5.5—8.0 7.7—10.8 4.7—5.6* 58— 81 11—14 93* 4♁♁ 1090—1180 27.0—29.0 5.3—6.1 7.3—9.7 4.7* - 13—14 bulbus dorsobidentatus ?♀♀ 880—924 17.2—18.3 5.9—6.0 11.0—11.1 2.6* 69 10—11 ? ?♁♁ 748—880 21.2—23.4 5.0—5.3 7.5—8.7 4.0* - 10—11? ludwigi ?♀♀ 780—945 18.6—22.5 4.8—5.9 5.9—6.8 4.6* 68—69 12 75* ?♁♁ 690—780 18.6—22.5 5.8—5.9 5.9—6.8 5.6* - 12 isthmus dubius ? ♀♀ 980—1200 25.1—30.7 5.4—6.0 9.2—9.5 3.4* 60—68?? ?♁♁ 760—1010 26.2—30.3 5.3—5.7 8.4—10.1 3.7* - 11* isthmus 8♁♁ 802—968 24.3—32.2 4.7—5.4 8.1—10.0? - 9—14? filiformis 1♁ 780 23.5 4.3 8.8 4.5* - 5.8* 70 isthmus japonicus 100♀♀ 878—1201 21.1—38.1 5.7* 6.7—12.6 5.5* 58—72? 55* 100♁♁ 696—1002 17.9—39.2 4.7* 7.7—12.2 3.5* -? metacorpus leperisini ? ♀♀ 820—970 22.3—24.8 5.6—5.8 6.9—8.2 5.4* 66—69 7* 78* ?♁♁ 740—920 22.0—25.0 6.0—6.3 8.2—8.4 2.8* - 7* isthmus ludwigi 20♀♀ 1090—1350 23.0—35.0 3.5—6.6 5.0—9.0 5.6—5.8* 68* 12 67* 9♁♁ 1000—1120 30.0—36.0 5.1—5.8 7.1—9.0 4.9—5.2* -? isthmus nepenthicola ? ♀♀ 2000—2400 28.0—35.0 5.6—5.8 9.0—10.0? 77?? ?♁♁ 1360—1600 30.0—45.0 4.0—5.0 12.0—15.0? -?? ?♀♀ 2300—2880 27.6—35.5 5.9—7.2 9.7—12.0? 76—82?? ?♁♁ 1360—1870 32.0—45.5 4.6—5.6 12.0—15.7 4.0* -?? pycnus ?♀♀ 1000—1400 18.0 8.0 8.5 4.7* 73?? ?♁♁ 800—1200 21.0 6.8 9.0 3.9* -?? ?♀♀ 1170—1410 16.0—22.0 6.1—8.0 8.0—10.0 6.0 71—77?? ?♁♁ 800—1200 21.0—27.0 5.7—7.4 8.0—10.0 3.5—4.0 -?? 12♀♀ 1170—1410 16.0—21.5 6.1—8.0 7.6—10.4 5.8* 71— 77 11—14 ? 15♁♁ 900—1222 20.6—26.9 5.7—7.4 7.9—10.4 4.1* - 10—13? redivivoides ?♀♀ 980—1700 17.0—24.0 5.0—8.0 8.0—10.0 5.2* 64—70?? ?♁♁ 810—1280 23.0—27.0 5.0—6.5 8.0—10.0 4.0* -?? zymosiphilus ?♀♀ 870—2170 13.6—33.1 5.4—10.3 6.0—12.9 4.8* 53—82 16* 57* ?♁♁ 730—1340 18.2—33.9 4.6—7.2 6.7—10.1 4.5* - 14* metacorpus 24♀♀ 942—1373 18.7—25.7 4.9—8.2 8.3—12.2 5.6* 62— 73 10—14 ? 28♁♁ 653—1098 17.3—32.7 4.6—6.1 7.9—11.8 2.9—3.3* - 9—13? ……continued on the next page Species sex L a b c c̕ V Stoma Excretory pore/neck length lenght (%) or position TABLE 2 . (Continued) redivivus ?♀♀ 2560 30.0—35.0 10.0—12.0 12.0—15.0 4.6* 70* 14—15 79* silusiae ?♁♁ 1900 35.0—40.0 8.0—9.0 12.0—15.0 3.2* - 14—15 isthmus base silusiae 1♀ 2500??????? 1♁ 1700 21.8* 7.1* 9.7* 3.0* -? 73* isthmus leucocephalus ? ♀♀ 1000—1100 20.8—23.2 5.9—6.4 7.6—7.9? 66—67? 81*?♁♁ 900—940 27.0—32.0 4.9—5.5 7.4—9.7 4.1* -? isthmus base parasiticus ?♀♀ 900—1450 28.0* 7.5* 7.5* 4.8* 68* 17* 82*?♁♁ 780—1120??? 4.5* -? isthmus base?♀♀ 1040—1370?????? 76*?♁♁ 950—1240??? 5.3* - 11* isthmus?♀♀ 1015—1750 26.4—35.0 6.5—9.6 6.6—13.5 7.3* 57—80 7*??♁♁ 1190—1205 28.3—31.2 6.5—9.6? 4.2* -???♀♀ 1315—1515 21.6—29.1 6.5—6.9 8.7—10.7 4.7* 66— 68 12—14 90*?♁♁ 1125—1230 25.0—29.3 5.6—6.2 7.3—8.8 3.5* - 12—14 bulbus?♀♀ 1300—2100 21.0—31.0 6.0—9.2 8.0—12.0? 62— 70 12—16 ??♁♁ 1100—1840 22.0—35.0 5.9—8.3 8.0—11.0? - 12—16? silusiae ? ♀♀ ???????? 76♀♀ 1220—2090 19.0—31.2 5.7—9.2 7.2—11.6 7.0* 56—71 14—18? 75♁♁ 705—1806 21.0—35.4 4.1—8.3 6.9—11.5 4.6* - 9—17? leucocephalus 6♀♀ 840—1185? 5.0—6.8 7.4—8.6? 65— 71 9—12 ? 2♁♁ 870—867? 5.0—5.5 7.2—7.9? - 9—10??♀♀ 1110—2090 19.0—31.0 6.0—9.5 7.0—11.0 6.0—7.0 58—71???♁♁???? 4.2* -?? silusioides ? ♀♀ 2200—2600 21.0—29.0 8.7—9.6 11.0—13.0 6.2* 66—78? 77?♁♁ 1700—2100 25.0—38.0 6.6—8.3 9.0—13.0? -? isthmus sp. n. 11♀♀ 906—1217 18.3—30.3 4.3—5.7 7.4—9.4 4.5—6.5 64— 68 10—12 52—58 10♁♁ 817—1183 25.0—34.9 4.0—5.7 8.1—11.2 3.3—4.9 - 10—12 metacorpus ventrodentatus ? ♀♀ 847—1112 16.0—17.0 5.0—8.0 7.0—9.0 4.6* 63—74 6*??♁♁ 581—647 20.0—25.0 4.0 5.0—7.0 4.1* -?? ……continued on the next page Species Corpus/isthmus Postvulval sac/body Tail Vulva-anus/body width Country or Habitat Reference TABLE 2. (Continued) width or Spicules or Gubernaculum ceylonensis 2.5* 3.0* 138—139* 4.7* Sri Lanka Hechler (1971b) ? 87—95 143* 30—34 Latex exuding in rubber tree dorsobidentatus ? 2.8* 83—83 3.5* Germany Rühm (1956) ? 22—26 86—114 14—18 Frass of insects in oak ludwigi 3.1*? 105—140? Germany Rühm (1956) ? 23—24 98—116 14—17 Frass of insects in oak and beech dubius ?? 87*? Canada Sanwal (1960) ? 57—72 95* 25—36 Frass from mines of insects ? 39—45 85** 26—30 Sanwal̕s material re-examined Hechler (1971a) filiformis 2.3* 22 102* 14* India Sukul (1971) Thermal spring japonicus 3.4*, 5.5* 2.4* 86—140** 7.1* Japan Yokoo & Ota (1961) 3.8* 27 70—117** 13 Decaying pear fruit on the standing tree leperisini 4.7* 2.7* 129*? North Dakota (USA) Massey (1974) 58* 91* 28* Bark beetles in green ash ludwigi 2.2* 2.8* 54—91 6.9* Germany de Man (1910) 2.2* 22 58—75 14* White slime in oak nepenthicola ???? Indonesia Menzel (1922) ? -?? Pitcher plant ???? Indonesia Micoletzky and Menzel (1928) ? 59—71?? Menzel̕s material re-examined pycnus ? absent?? 3.2* Utah (USA) Thorne (1938) ???? Slime in cottonwood ???? Hungary Andrássy (1958 , 2005 )? 50—70? 25—27 Several ? present 151**? Utah (USA) Hechler (1971a) ? 60—70 129** 25—27 Thorne̕s material re-examined redivivoides 4.7* 3.3* 79* 5.7* United Kingdom Goodey (1943) 4.0* 37—45 62* 14—18 Fruit flies from greenhouse zymosiphilus 10.4* 3.2* 120—180 4.0* Germany Brunold (1950 , 1954 ) 5.6* 24—29 96—160 16—17 Fruit flies from greenhouse ???? United Kingdom and Germany Hechler (1971a) ? 21—34? 10—19 Goodey̕s and Brunold̕s material re-examined ……continued on the next page Species Corpus/isthmus Postvulval sac/body Tail Vulva-anus/body width Country or Habitat Reference width or Spicules or Gubernaculum TABLE 2 . (Continued) redivivus 3.1*?? 7.8* Germany de Man (1913 , 1914 ) silusiae ? 55—62?? Beer filters silusiae ? 2.8*?? France Aubertot (1925) 2.1*??? Mashed potatoes in fermentation carried by fruit flies leucocephalus 2.4*??? Virginia (USA) Steiner (1936) ???? Fungus in scarlet oak wood parasiticus 2.7* 2.6* 125—210 5.1* Indonesia Sandground (1939) ? 65—70 100—150 25—28 Stomach of monkey ???? Goodey (1945) 4.4* 52—55 102* 25—28 2* 2.3* 157* 5.6* Brazil Corrêa de Carvalho & Álvarez- Corrêa (1953) 1.4* 56 100* 39* Tomato paste 2.1*? 123—175? Germany Rühm (1956) ? 54—65 140—154 27—30 Frass of insects in the base of beech ?? 120—170? Hungary Andrássy (1958 , 2005 )? 50—64 140—150 27—30 Several silusiae 1.8*??? Belgium Yuen (1968) Origin unknown ???? Florida (USA) Hechler (1970 , 1971a )? 50—64? 24—32 Agar culture from soil leucocephalus ???? Virginia (USA) Hechler (1971a) ? 36—39? 18—20 Steiner̕s material re-examined ???? Italy Zullini (1982) ? 50—64?? silusioides 2.4??? Russia Tsalolikhin (1965) ? 53—62? 9—13 Saprobiotic sp. n. 2.2—2.8 2.0—3.4 112—144 3.9—6.6 Iran Present paper 2.2—2.7 24—32 76—124 12—17 Wetwood canker in elm tree ventrodentatus ?? 102—125? Germany Heindl-Mengert (1956) ? 16—21 78— 97 10—13 Slime of living deciduous trees Measurements from drawings. ** Measurements from other measurements. (?) Unknown. (-) Character absent. TABLE ³. Morphometrics (in µm) of Panagrobelus species. Species sex L a b c c̕ V Stoma length Excretory pore/neck lenght (%) or position coronatus 6♀♀ 463—543 20.0 4.2 19.4 4.1* 60 9—11 57* 2♁♁ 517—527 20.3 4.2 16.5 2.0* - 7—9 isthmus hunti 20♀♀ 973—1037 23.0—36.0 5.0—7.0 16.0—21.0 2.0—4.0 54— 61 11—15 64—80, isthmus base 20♁♁ 852—925 31.0—34.0 6.0—9.0 17.0—18.5 1.9* - 6—8 94 —152 incisus 1♀ 1000 20.0 5.5 21.0? 59?? 1♁ 900 28.0 4.1 20.0 1.8* -?? coronatus ?♀♀ 690—780 21.9—22.3 3.4—4.6 17.1—17.9? 57— 59 11—15 ??♁♁ 600—690 19.0—24.6 4.1—4.7 16.4—17.1 1.8* - 11? scolyti 4♀♀ 700—800 23.0 4.7 22.0 1.4—1.5* 62 12* 80—87* 3♁♁ 750 20.0 4.2 17.0 1.6—1.7* -? isthmus base or bulb phloeosini ? ♀♀ 650—760 18.5—23.7 4.5—4.6 23.7—24.8 1.4* 57—60 13* 80*?♁♁ 520—650 25.4—27.7 3.6—4.2 16.2—18.5 2.1* -? isthmus stammeri ?♀♀ 810—1110 21.1—23.1 4.4—6.0 19.3—21.1 2.0* 56—59 8* 72*?♁♁ 690—780 22.3—27.9 4.2—4.3 17.1—19.7 2.0* -? isthmus 20♀♀ 676—882 20.0—36.0 5.0—7.0 16.0—21.0 2.0—4.0 54— 61 8—13 64—80 30♁♁ 627—833 26.0—35.0 4.0—6.5 14.0—22.5 1.0—3.0 - 7—12 bulb continued. Species Corpus/isthmus Postvulval sac/body Tail Vulva-anus/body width Country or Habitat Reference width or Spicules or Gubernaculum coronatus 2.1*? 22—28 7.2* Germany Fuchs (1930) ? 16—18 30—32 6 * Frass of insects hunti 1.9* 0.3* 54—62 11.6 United Kingdom Stock et al. (2002) ? 28—32 47—52 13—15 Bark of a dead elm with bark beetles incisus ? 0.2* 48**? Massachusset (USA) Thorne (1939) ? 27* 45** 17* Under bark of a dead twig of the umbrella-pine coronatus ?? 39—46? Germany Rühm (1956) ? 23—24 35— 42 12—14 Frass of insects in several species trees scolyti 1.6* 0.3* 27* 8.9* New Mexico (USA) Massey (1964 , 1974 ) ? 24* 38* 13* Frass of insects in several species trees phloeosini 2.1* 0.3* 34*? Virginia (USA) Massey (1974) ? 22* 34* 10* Frass of insects in eastern redcedar stammeri 2.0*? 42—53? Germany Rühm (1956) ? 24—25 35— 46 11—14 Frass of insects in several species trees 1.3—2.0 0.4—0.5 34—46 10.0 United Kingdom Stock et al. (2002) 1.5—2.5 21—28 33—46 13—18 Bark of a dead sapling elm infested with bark beetle TABLE 4. Morphometrics (in µm) of Plectonchus species.

Species sex	L	a	b	c	c̕	V	Stoma length Excretory pore/neck length (%) or position
ateri 1♀	694	23.9	6.0	8.9	2.0*	74	10 42*
1♁	583	24.3	5.5	12.9	2.2*	-	10 metacorpus
as cucumis 7♀♀ cuniculari 1♀	900—1120 752	12.8—16.0 19.3	5.2—6.4 6.2	6.9—9.0 10.3	1.8* 3.9*	72—73 74	10—12? 6 45*
?♁♁	?	?	?	?	?	?	6 metacorpus
extrematus 10♀♀ 10♁♁	750—900 700—780	32.0—34.0 34.2—35.4	4.6—5.8 4.4—4.8	8.4—9.2 10.5—11.4	3.1* 3.0*	78—80 -	????
galeatus 18♀♀ 20♁♁	492—715 442—627	20.0—33.0 23.0—39.0	3.7—5.1 3.7—5.1	7.8—12.1 8.2—11.4	3.7—6.9 2.8—4.7	71—81 -	9 73*? isthmus
ligniperdae 1♀ longevulvus 20♀♀ 17♁♁	461 438—628 440—581	21.8 21.0—30.0 18.0—32.2	5.2 3.6—4.5 3.5—4.7	11.8 10.4—14.7 9.7—14.7	? 1.5—4.0 1.4—2.8	76 49—78 -	8 48* base of procorpus 5—9 50* 4—9 metacorpus
molgos ?♀♀?♁♁	570—600 510—570	20.4—24.4 25.1—28.1	5.1—5.6 4.2—4.9	9.7—11.3 9.8—12.3	3.5* 2.5*	75 -	4* 48*? metacorpus
as Anguilluloides 11♀♀ zondagi 11♁♁	415—680 460—580	17.0—28.0 17.0—31.0	3.7—5.5 4.2—5.7	9.2—13.6 9.6—14.5	2.4* 2.4*	71—79 -	5* 41* 5* base of procorpus
procerus ?♀♀	500—1130	21.8—33.0	3.7—5.3	8.4—12.9	= 4.7*	71—78	8*?
?♁♁	530—1110	27.8—38.3	3.9—5.8	11.5—19.2	3.2*	-	??
as Anguilluloides ?♀♀ tremebundus ?♁♁	647—750 645—840	23.0—30.6 26.3—30.0	4.1—4.5 5.6—5.9	9.7 5.7—6.2	5.2* 7.5	74—75 -	8—9 = 33 6—9 base of procorpus
sucicola ?♀♀?♁♁	1590—2510 1560—2370	41.0—53.0 40.0—52.0	7.0—9.3 7.0—9.3	10.5—16.0 13.0—15.0	2.0—4.3* 3.9*	66—71 -	? 50*? metacorpus
wyganti 3♀♀	700	30.0	4.5	11.5	4.8*	77	4.7* 38*
2♁♁	600	32.0	4.6	10.8	3.1*	-	? base of procorpus

……continued on the next page Species Corpus/isthmus Tail Vulva-anus/tail Vulva-anus/body width Country or Habitat Reference or Spicules or Gubernaculum TABLE 4. (Continued) ateri 2.4* 78 1.4* 1.7* Germany Fuchs (1930) ? 45 18 8 Bark beetle galeries cucumis 2.9 49*?? India Nama & Soni (1979) Slimy flux of melo cuniculari 1.9* 73 1.7* 5.3* Germany Fuchs (1930) ? 50 23* 17* Frass of bark beetle extrematus 1.9? 1.2* 2.3* Austria Gunhold (1952)