Acrolobus longigubernaculum, Amirzadi, Negin, Shokoohi, Ebrahim, Eskandari, Ali & Abolafia, Joaquín, 2012

Amirzadi, Negin, Shokoohi, Ebrahim, Eskandari, Ali & Abolafia, Joaquín, 2012, Description of Acrolobus longigubernaculum sp. n. (Nematoda, Rhabditida, Cephalobidae) from Iran, the second species of the genus, Zootaxa 3407, pp. 61-68 : 62-67

Acrolobus longigubernaculum sp. n.

( Figs. 1–3 & 4 C, D)

Material examined. Eleven females and five males, in good state of preservation. Measurements. See Table 1 .

Description. Adult: Body 0.72–0.98 mm long, almost cylindrical, ventrally curved after fixation. Lateral fields with three incisures, occupying 17–19% of midbody diameter. Lip region set off from the neck. Six rounded, leaflike lips, the lateral ones somewhat smaller and almost transparent in their outer part, being visible under LM only the basal part of lip, this more or less triangular with rounded tip. Labial probolae absent. Amphidial opening circular. Stoma cephaloboid, cheilostom with bar-like rhabdia, gymnostom very short, stegostom long having metastegostom with a small dorsal denticle. Pharynx cephaloboid; corpus cylindrical, 2.7–3.2 times isthmus length, procorpus longer than metacorpus; isthmus narrower than metacorpus; basal bulb ovoid, with median valvular apparatus. Nerve ring surrounding the basal part of pharyngeal corpus, at 52–61% of neck length. Excretory pore located at level of basal part of pharyngeal corpus, 50–56 annuli from lip region or at 66–69% of neck length. Deirids located at level of isthmus, at 59–64 annuli from lip region or 71–75% of neck region. Cardia conoid, surrounded by intestinal tissue.

Female: Reproductive system monodelphic-prodelphic, located on the right-hand side of intestine. Ovary with double flexure in postvulvar region, with single row of oocytes. Oviduct short. Spermatheca well developed, offset, with sperm, 0.8–1.5 times the corresponding body diameter long. Postuterine sac 0.9–1.3 times the corresponding body diameter long, smooth or more or less lobed. Vulva slightly protruding, located posterior to the middle part of body. Rectum 1.0–1.2 times anal body diameter. Tail conical ending in a fine mucro. Phasmids at 48–55% of tail length.

Male: Body curved ventrally after fixation. Reproductive system monorchic, testis reflexed dorsad anteriorly. Tail conical, distally curved ventrad, and ending in a fine mucro. Three pairs of precloacal genital papillae. Five pairs of caudal genital papillae are present along the tail comprising: one ventral pair, one lateral pair, one dorsal pair, and two pairs near tail terminus. Spicules curved ventrally: manubrium almost straight and slightly conoid, calamus with similar width to manubrium, and lamina ventrally curved. Gubernaculum long and well developed, 12–16 mm long or about 50% of the spicule length, slightly curved distally.

Diagnosis. The new species is characterized by its body length of 0.72–0.98 mm in females and 0.73–0.84 mm in males, annulated cuticle, lateral fields with three longitudinal incisures, slightly offset lip region 7–11 μm wide, leaf-like lips, stoma 12–16 µm long, corpus 2.7–3.2 times isthmus length, spermatheca 23–53 µm long, postuterine sac 27–49 µm long or 0.9–1.3 times the corresponding body diameter, vulva located slightly posterior to middle of body (V = 61–65), conical female tail with fine short mucro (47–58 µm, c = 13.9–18.5, c’ = 2.4–3.2), conical male tail bearing a fine mucro (47–50 µm, c = 14.8–17.5, c’ = 2.0–2.3), spicules 26–30 μm long and ventrally curved, and gubernaculum 12–16 µm long (50% of spicule length).

Relationships. The new species is similar to the type species of the genus, Acrolobus emarginatus , but can be distinguished by its longer body (0.72–0.98 vs 0.45–0.62 mm in females and 0.73–0.84 vs 0.43–0.51 mm in males), longer pharynx (154–213 vs 120–150 µm), longer postvulvar sac (27–49 vs 17–25 µm), longer and differently shaped tail (47–58 μm and ventrally straight vs 32–41 µm and with similar dorsal and ventral morphology in females and 47–50 μm and strongly ventrally curved posteriorly vs 30–35 µm and almost straight in males), longer and differently shaped spicules (26–30 µm, strongly bent ventrally vs 17–21 µm, almost straight), and longer gubernaculum (12–16 vs 8–9 µm).

Type habitat and locality. The specimens were collected in association with the rhizosphere of Sonchus arvensis L., in Shahrood (Semnan province), in northeastern Iran.

Type material. Female holotype , eight female and three male paratypes deposited in the nematode collection of the Department of Plant Protection, College of Agriculture, Shahid Bahonar University of Kerman, Iran. Three female paratypes and one male paratype deposited in Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Spain.

Etymology. The specific epithet refers to the length of the gubernaculum in comparison with the type species.

Figures

FIGURE 1. Acrolobus longigubernaculum sp. n. A: Neck. B: Anterior end. C: Lip region (surface view). D: Female reproductive system. E: Female posterior end. F: Entire Female. G: Entire male. H: Male posterior end. I: Lateral field.

FIGURE 2. Acrolobus longigubernaculum sp. n. (LM). A: Neck. B: Amphid (arrow). C: Lip region. D: Stoma. E: Excretory pore (arrow). F: Deirid (arrow). G: Lateral field.

FIGURE 3. Acrolobus longigubernaculum sp. n. (LM). A: Female reproductive system. B: Entire female and male. C, D: Vaginal region. E: Female posterior end. F, G: Male posterior end (in G, arrows indicate precloacal genital papillae).

FIGURE 4. Posterior end of Acrolobus species. A. emarginatus (de Man, 1880) Boström, 1986. A: Female. B: Male. A. longigubernaculum sp. n. C: Female. D: Male.

Tables

TABLE 1. Measurements of Acrolobus longigubernaculum sp. n. (all measurements in mm).

Locality	Shahrood
Habitat	Sonchus arvensis
Character	Holotype female	Paratype females Mean ± S.D. (range)	Paratype males Mean ± S.D. (range)
n	1	10	5
Body length	782	804.6 ± 67.6 (721–978)	784.2 ± 45.2 (726–837)
a	23.7	25.3 ± 1.5 (23.3–28.3)	25.5 ± 3.1 (21.4–28.3)
b	3.7	3.9 ± 0.5 (3.5–5.3)	4 ± 0.3 (3.6–4.5)
c	16.3	15.5 ± 1.4 (13.9–18.5)	16.1 ± 1.1 (14.8–17.5)
c´	2.7	2.7 ± 0.3 (2.4–3.2)	2.2 ± 0.1 (2.0–2.3)
V	64	63 ± 1.5 (61–65)	–
Lip region diam.	8	8.7 ± 1 (8–11)	7.8 ± 0.4 (7–8)
Stoma	16	14.7 ± 1.3 (12–16)	15 ± 1 (14–16)
Pharyngeal corpus length	145	137 ± 15.1 (101–152)	137.4 ± 3.9 (132–142)
Isthmus length	43	42.3 ± 3.4 (37–47)	37.2 ± 6.9 (26–44)
Bulb length	24	22.6 ± 2.3 (19–26)	23.4 ± 2.2 (20–26)
Pharynx length	213	197.8 ± 19.9 (154–209)	198.8 ± 6.1 (188–203)
Nerve ring to ant. end	126	124.5 ± 8.9 (112–135)	124 ± 3.5 (121–128)
Excretory pore to ant. end	128	128 ± 6.9 (118–138)	125 ± 3.2 (121–128)
Deirid to ant. end	142	136.6 ± 5.0 (131–142)	139 ± 4.8 (134–144)
Neck length	229	224.0±19.5 (168–224)	213.8±5.6 (204–218)
Annuli width at midbody	2	1.9 ± 0.3 (1–2)	2.2 ± 0.4 (2–3)
Cuticle thickness	2	2±0.3 (1.7–2.2)	2.2 ± 0.4 (2–3)
Body diameter at: neck base	12	11.6 ± 0.5 (11–12)	11.8 ± 0.4 (11–12)
midbody	33	31.8 ± 2.1 (29–37)	31 ± 2.3 (29–34)
anus	18	19.3 ± 1.4 (17–21)	22.2 ± 0.4 (22–23)
Lateral field width	6	5.4 ± 0.7 (5–7)	5.0 ± 0.0 (5)
Vagina length	10	10.3 ± 0.8 (9–12)	–
Ovary length	233	248.1 ± 48.7 (184–340)	–
Anterior genital branch	148	137.8 ± 24.3 (94–176)	–
Spermatheca length	29	40 ± 11.8 (23–53)	–
Postuterine sac length	31	36.2 ± 7.8 (27–49)	–
Rectum length	23	21.8 ± 2.9 (18–27)	?
Tail length	48	52 ± 3.6 (47–58)	48.6 ± 1.5 (47–50)
Vulva to anterior end	498	509 ± 48.9 (453–634)	–
Spicule length	–	–	28 ± 1.6 (26–30)
Gubernaculum length	–	–	14.2 ± 1.5 (12–16)