Merlinius

Merlinius Siddiqi, 1970 (ref. ID; 5929, 7200)

Family Belonolaimidae (ref. ID; 6182)

Subfamily Merlininae (ref. ID; 5929)

Merlinius brevidens (Allen, 1955) Siddiqi, 1970 (ref. ID; 7200)
Merlinius circellus Anderson & Ebsary, 1982 (ref. ID; 7200 original paper)
Merlinius joctus (Thorne, 1949) Sher, 1974 (ref. ID; 7200)
Merlinius laminatus (Wu, 1969) Siddiqi, 1970 (ref. ID; 5929 additional report)
See; Scutylenchus laminatus (Wu, 1969) (ref. ID; 7200)
Merlinius leptus (Allen, 1955) (ref. ID; 5929)
Merlinius loofi Siddiqi, 1979 (ref. ID; 7200)
Merlinius mamillatus n. comb. (ref. ID; 5929)
Syn; Scutylenchus mamillatus (ref. ID; 5929)
Merlinius paraobscurus (Mulvey, 1969) Kheiri, 1972 (ref. ID; 7200)
Merlinius plerorbus Anderson & Ebsary, 1982 (ref. ID; 7200 original paper)
Merlinius processus Siddiqi, 1979 (ref. ID; 7200)
Merlinius productus (Thorne, 1949) Sher, 1974 (ref. ID; 7200)
Merlinius tesselatus (Goodey, 1952) Siddiqi, 1970 (ref. ID; 5929)
Merlinius tetylus Anderson & Ebsary, 1982 (ref. ID; 7200 original paper)

Merlinius circellus Anderson & Ebsary, 1982 (ref. ID; 7200 original paper)

Diagnosis

Females of Merlinius circellus n. sp. are most similar to those of M. loofi Siddiqi, 1979 in stylet length and general body features, but are more finely annulated with a greater number of tail annules, at least 70 versus 40-60. Other differences are a wider lateral field, 8-9 µm versus about 5 µm in M. loofi, the spherical spermathecae which are not lobed, large sperms of 2 µm in diameter, presence of dense refractive inclusions in the cuticule, and the position of the hemizonid, which is at least four body annules anterior to the excretory pore versus less than two in M. loofi. (ref. ID; 7200)

Descriptions

Holotype (female): L=647 µm, a=32, b=5.5, c=8.5, c'=6.3, V=54. Body linear, posterior half slightly arcuate, annules distinct, 0.4-0.9 µm wide. Head low, apex flattened, continuous with body, marked by three annules. Central tube and basal ring of head skeleton refractive, radial lamina indistinct. Stylet 10 µm long, conus attenuated, knobs with sloping anterior surfaces. Dorsal esophageal gland orifice about 2 µm below stylet. Posterior cephalids 15 µm posterior to head end, below stylet. Excretory pore indistinct, 99 µm posterior to head end, at anterior level of basal esophageal bulb. Hemizonid large, three body annules wide, 4 µm anterior to excretory pore. Deirids minute, distinct, at a level between excretory pore and hemizonid. Lateral field 9 µm wide, outer of six incisures crenate, usually obscured by interspaced refractive inclusions. Metacorpus strongly developed, occupying entire width of body cavity. Ovaries outstretched, extending 187 µm anterior and 198 µm posterior to vagina. Spermathecae spherical, not lobed, filled with sperms of about 2 µm diameter, at 52 µm anterior and 35 µm posterior to vagina. Lateral margins of vulva elevated, smooth. Vagina lining weakly cuticularized, depth 7 µm. Tail linear, elongate-conoid, terminus sharply pointed. Ventral surface of tail with 77 annules extending to tail terminus. Phasmids 27 µm posterior to level of anus, at 37% of tail length. (ref. ID; 7200)

Paratype (female): L=517 µm, a=26, b=5.4, c=8.0, c'=5.6. Female similar to holotype except as follows. Stylet 9 µm long, posterior cephalids 12 µm from head end. Excretory pore 79 µm from head end, hemizonid four annule widths anterior. Lateral field 8 µm wide near midbody. Ovaries extending 139 µm anterior and 116 µm posterior to vagina, spermathecae at 35 µm anterior and 29 µm posterior to vagina. Vagina depth 6 µm. Tail ventrally arcuate, with 72 annules. Phasmids 23 µm posterior to level of anus. (ref. ID; 7200)

Allotype (male): L=540 µm, a=34, b=4.4, c=7.1, c'=6.3, T=31. Similar to females in general characteristics. Head higher and more narrowly rounded than in female, bearing four fine annules. Stylet 11 µm long. Cephalids not observed. Excretory pore 85 µm posterior to head end, about midway between metacorpus and basal esophageal bulb. Hemizonid four annules anterior to excretory pore. Deirid indistinct, between level of hemizonid and excretory pore. Tail elongate-conoid, terminus with a ventral projection. Phasmids 32 µm posterior to cloacal opening. Bursa narrow, termination at tail end obscure. Spicules 21 µm long, manubrium cephalated, shaft uniformly cylindrical, blade arcuate, tapered, distal end indented. Gubernaculum 7 µm long, distal end attenuated. (ref. ID; 7200)

Type host and locality

Collected from sandy soil, Bathurst Island, Canadian high arctic. Host plant unknown. (ref. ID; 7200)

Type designations

Holotype (female), type slide No.254, collection No.7402. Allotype (male), type slide No.254a. Paratypes (one female, one male), same data as for allotype. Deposited in the Canadian National Collection of Nematodes. (ref. ID; 7200)

Merlinius laminatus (Wu, 1969) Siddiqi, 1970 (ref. ID; 5929 additional report)

See

Scutylenchus laminatus (Wu, 1969) (ref. ID; 7200)

Descriptions

Female: The vulva invaginates into the body forming a broad, deep atrium. The vaginal walls are greatly thickened proximally (at point of attachment to body cuticle) and recurve around the lateral sides of the vulval atrium. The tail is uniformly concoid and rarely deviates in shape. The cuticle at the terminus is thickened and irregularly sculptured internally. A prominent postanal intestinal sac extends to about midtail. (ref. ID; 5929)

Male: The spicula and gubernaculum shape are consistent with the generic diagnosis of Merlinius by Siddiqi (1970). The proximal ends of the spicula, however, are more bluntly rounded and indented than those illustrated by Wu (1969). The cloacal opening is covered by single or double folds of cuticle. The narrow, nearly linear in profile bursa extends out from the body no more than 7 µm. Like the lateral field, the cuticle of the bursa is distinctly granular. (ref. ID; 5929)

Cuticle. In the original description the presence of longitudinal striae on the body cuticle was not reported. Near midbody there are 56-58 striae (cross sections of three females, one males) which are separated by 0.7-1.4 µm. The close proximity of these striae give the cuticle a laminated appearance from a side view. The subcuticular annules, which are a prominent feature of this species, occur with a periodicity of two for each body annule. Their refractive striae tend to obscure the transverse body striae when focusing upward or downward along the body curvature. (ref. ID; 5929)
Head and Stylet. The head, which is set off by a deep constriction, has six to eight fine transverse annules which extend anteriorly around the contour of the apex. It is divided by shallow longitudinal striae into six lobes that are proportinate in size to the lips. The larger, more prominent subdorsal and subventral lips each have a single papilla opening at the outer contour while no papilla was observed on the reduced lateral lips. The delicate, acuminate stylet has small rounded knobs that usually slope posteriorly. The protractor muscles of the stylet appear to be attached anteriorly to the body wall at junction with the head, but at this level they are obscured by the rather prominent papillary nerves that enter the head through the foramina of the septum. (ref. ID; 5929)
Excretory pore. The excretory pore is either immediately posterior to the hemizonid (54% of specimens) or one to two annules posterior in females and as distant as five annules in males. The excretory pore is usually located at a level near the beginning of the last third of the isthmus, but may be as far posterior as the anterior third of the basal esophageal bulb. (ref. ID; 5929)
Phasmids. Dimensions of phasmids usually are based on the refractive, expanded subcuticular part. The phasmid opening is of smaller diameter and generally obscure in one-end view. The phasmids of M. laminatus can be described as relatively large for species of Merlinius, being similar to those of M. leptus (Allen, 1955) Siddiqi, 1970. The right and left phasmid are either at the same level near midtail or separated by as much as half an anal body width. (ref. ID; 5929)

Remarks

The presence and number of longitudial striae in M. laminatus establishes a close affinity to M. tesselatus (Goodey, 1952) Siddiqi, 1970. These species differ respectively in the following: coarseness of body annulation, less than 2 µm wide at midbody vs. 2.8 µm wide in M. tesselatus; number of longitudal striae, at least 56 vs. 48; shape of the tail and its terminus, conoid with a distinctly narrow terminus vs. subcylindrical with a broadly rounded terminus; number of annules on tail, at least 50 vs. less than 40; ratio of anal body width to tail length, over 3.0 vs. less than 2.6. Merlinius laminatus also differs from M. tesselatus by the presence of a postanal intestinal sac, a thicker cuticle at the tail terminus, and, in the male, by more broadly rounded distal ends of the spicules. Merlinius laminatus also is closely related to Tylenchorhynchus mamillatus Tobar-Jimenez, 1966. The six incisures in T. mamillatus, character of the gubernaculum and spicules, and absence of a perioral disc place this species in the genus Merlinius, as defined by Siddiqi (1970). The large phasmids sloping stylet knobs, areolated lateral field, and subdigitate tail terminus prompted Jairajpuri (1971) to erect the genus Scutylenchus to accomodate this species. However, species of Merlinius have a wide gradation in phasmid size, which would appear to include those of S. mamillatus, and negates the generic value of this character. Sloping stylet knobs and areolated lateral fields are common to species in the subfamilies Merlininae and Tylenchorhyncinae and a subdigitate tail is a variant form in some species with conoid tails. I therefore consider that the genus Scutylenchus is synonymous with Merlinius and propose that S. mamillatus be transferred to Merlinius. Merlinius laminatus differs from M. mamillatus n. comb. primarily in length of the female tail (62-88 vs. 48-54 µm; c'>3 vs. 2.0-2.2), number of tail annules (>50 vs. 25-32) and in having an annulated tail terminus which is smooth in M. mamillatus. (ref. ID; 5929)

Merlinius plerorbus Anderson & Ebsary, 1982 (ref. ID; 7200 original paper)

Diagnosis

Merlinius plerorbus n. sp. can be differentiated from all other species of the genus Merlinius by the elongate-conoid tail and narrowly rounded tail terminus. In other species the tail are convex-conoid, subcylindrical, or if elongate-conoid, have a pointed or finely rounded terminus. Merlinius plerorbus n. sp. has many characters in common with M. joctus (Thorne, 1949) Sher, 1974, but differs in having coarser body annules, fewer tail annules, 38-40 versus more than 50 in M. joctus, and a more rounded tail versus finely rounded. (ref. ID; 7200)

Descriptions

Holotype (female): L=591 µm, a=25, b=4.0, c=11.9, c'=3.0, V=56. Stylet length 17 µm. Egg (intrauterine) 64x17 µm. Body ventrally arcuate, annules distinct, coarse, 1.2-1.4 µm wide, cuticle containing refractive inclusions. Head constricted, subtruncated, bearing five distinct annules, basal ring of head skeleton well developed. Stylet conus attenuated, knobs 3 µm in diameter, anterior surfaces slightly sloping. Dorsal gland orifice 3 µm below stylet. Excretory pore 98 µm posterior to head, near metacorpus hemizonid 3 µm anterior, narrow. Deirid 97 µm posterior to head end. Lateral field at midbody 8 µm wide. Incisures 6, clearly visible. Metacorpus 17x10 µm, oval, basal esophageal bulb pyriform, 24x11 µm. Ovaries outstretched, extending anteriorly 204 µm into esophageal region, posteriorly 141 µm. Spermathecae lobed, containing sperm aggregates. Vulva depressed, vagina depth less than half of body width. Tail elongate-conoid, tapering to a rounded, smooth tip. Ventral surface of tail with 38 annules. Phasmids 20 µm posterior to level of anus. (ref. ID; 7200)

Paratypes (four females): L=579(542-632) µm, a=26(24-29), b=4.4(4.0-4.8), c=12(11-13), c'=3.3(2.8-3.8), V=56(54-58). Stylet length 16 µm. Body ventrally arcuate to varying degrees, width at midbody 21-24 µm, annules 1.0-1.5 µm wide. Head constricted, bearing five fine annules. Esophagus 126-141 µm long, metacorpus 14-16x10 µm, basal esophageal bulb pyriform, 25-28x11-13 µm. Stylet knobs rounded, 2.9-3.3 µm in diameter, anterior surfaces sloping. Excretory pore 89-105 µm posterior to head end, at levels from base to anterior end of isthmus, hemizonid 1.9-6.0 µm anterior. Deirids prominent, at levels between excretory pore and hemizonid. Ovaries extending anteriorly 164-193 µm, usually into esophageal region, and posteriorly 149-168 µm from vagina. Spermathecae irregular, comprised of three to six lobes, ranging from 39 to 65 µm anterior and 33 to 45 µm, posterior to vagina. Vulva depressed, vagina short, depth 5-8 µm. Tail 50(45-54) µm long, conoid, slightly arcuate, terminus rounded, smooth, or with a few coarse annules. Ventral surface of tail with 38-40 annules. Phasmids 19-24 µm posterior to anus, at 39-45% of tail length. (ref. ID; 7200)

Allotype (male): L=543 µm, a=29, b=3.6, c=10, c'=3.9, T=48. Stylet length 16 µm. Spicule length 20 µm. Gubernaculum length 7 µm. Head high, rounded, with five distinct annules. Excretory pore 90 µm, posterior to head end, just below metacorpus, deirid at same level hemizonid 2 µm anterior. Metacorpus fusiform, 19x10 µm, basal esophageal bulb pyriform, 21x10 µm. Tail linear, tapering to a narrowly rounded tip. Bursa moderately well developed, annulations coarser than on tail. Phasmids at 43% of tail length. (ref. ID; 7200)

Type host and locality

Collected root zone of chard and strawberry in a private garden. St. John's, Newfoundland, Canada. (ref. ID; 7200)

Type designations

Holotype (female), type slide No.253, collection No.7497. Allotype (male), type slide No.253a. Paratypes (four females), type slide Nos.253b, 253c, 253d, collection Nos.7497, 7501. Deposited in the Canadian National Collection of Nematodes. (ref. ID; 7200)

Merlinius processus Siddiqi, 1979 (ref. ID; 7200)

Descriptions

Female (10, from Canada): L=559(503-664) µm, a=21(19-24), b=4.8(3.8-5.1), c=11(9-13), c'=2.8(2.4-3.2), V=56(54-58). Stylet length 14(13-16) µm. Egg (11 intrauterine): 56(50-62)x19(16-21) µm. A small robust species with fine body annules 0.5-0.9 µm wide. Body linear to slightly arcuate, width 25(23-31) µm. Head offset from body, with five or six fine annules, of which the anteriormost are usually indistinct. Esophagus 116(100-134) µm long, metacorpus large, 12-18x10-12 µm, occupying all or nearly all of body cavity, basal esophageal bulb 22-29x12-13 µm. Esophagointestinal valve hemispherical or discoid, often appearing lobed. Excretory pore 88(77-99) µm posterior to head end, ranging from anterior third of isthmus to anterior third of basal esophageal bulb. Hemizonid small, one or three body annules anterior to excretory pore. Deirids generally obscure, slightly posteriad excretory pore. Ovaries outstretched, extending 215(143-277) µm anteriad, 208(149-244) µm posteriad, ending well into esophageal and caudal regions in most specimens. Spermatheca thin walled sperms in aggregates contained in two to five lobes. Rectum length less than anal body width. Tail conoid, 46(44-60) µm long, ventral surface with 46(44-60) annules. Tail terminus smooth, pointed in most specimens, sometimes narrowly rounded or mucronate. Phasmids 19(17-21) µm posterior to level of anus, at 39(32-45)% of tail length. (ref. ID; 7200)

Males (two, from Canada): L=474, 516 µm, a=26, 27, b=4.2, c=9, 11, c'=4.1, 3.3, T=44, 41. Stylet length 14 µm. Spicule length 20, 21 µm. Gubernaculum length 7, 8 µm. Head offset, with five and six annules. Metacorpus 12, 13 x 10, 8 µm; basal esophageal bulb pyriform, 20, 17 x 9, 10 µm. Excretory pore 90, 81 µm posterior to head end, hemizonid immediately anterior, deirids at same level. Tail conoid, terminus filiform, smooth. Phasmids 20 µm posterior to cloacal opening, at 36, 42% of tail length. (ref. ID; 7200)

Remarks

The distinctive features of this population from Canada are the extensive development of the reproductive system in females, the indistinctness of the excretory pore and duct, anus, deirids, and lateral incisures, and the density of refractive inclusions in the cuticle. (ref. ID; 7200)

Host and locality

Soil from root zone of 15-year-old box (Buxus L.) in a private garden, St. John's, Newfoundland. (ref. ID; 7200)

Merlinius tetylus Anderson & Ebsary, 1982 (ref. ID; 7200 original paper)

Diagnosis

Merlinius tetylus n. sp. is most similar to M. joctus (Thorne, 1949) Sher, 1974 from which it can readily be distinguished by the greater tail length of the female, 98 µm versus less than 70 in M. joctus, and by the greater number of tail annules, 100 versus less than 70 (cf. Siddiqi 1979). Merlinius tetylus differs further in having a greater body length, over 800 µm vesus less than 700 in M. joctus, by the more posterior position of the deirid, greater length of the basal esophageal bulb, 41 µm versus 27 µm in the lectotype of M. joctus, and by the irregular areolation of the lateral field. Merlinius tetylus differs from M. productus (Thorne, 1949) Sher, 1974 in having a greater tail length and number of annules, less acute tail terminus, and a shorter body length. (ref. ID; 7200)

Descriptions

Holotype (female): L=804 µm, a=30, b=5.3, c=8.2, c'=4.9, V=48. Stylet length 14 µm. Body linear, width at midbody 27 µm, annule width about 1 µm, subcuticle distinctly crenulate. Head low, subtruncated, constricted, bearing four fine, distinct annules and two or three indistinct annules on contour of head apex. Basal ring of head skeleton extending deeply into body. Stylet knobs rounded, 2.4 µm in diameter. Dorsal esophageal gland orifice 2.4 µm posterior to stylet. Posteriormost cephalids 12 µm posterior to head end. Excretory pore indistinct, 110 µm posterior to head end. Hemizonid narrow, 4 µm long, two annules anterior to excretory pore. Deirids 13 µm posterior to level of excretory pore, at anterior region of basal esophageal bulb. Lateral field 10 µm wide, incisures 6, distinct, areolated to base of esophagus, irregularly areolated on rest of body. Metacorpus 18x12 µm, about midway of total esophagus length, basal bulb subcylindrical, 41x14 µm, dorsal gland nucleus centered. Ovaries outstretched, extending anteriorly 283 µm into esophageal region, and 208 µm posteriorly. Spermathecae lobed, at 50 µm anterior and 44 µm posterior to vagina. Tail elongate-conoid, terminus narrowly rounded, smooth. Ventral surface of tail with about 100 fine annules. Phasmids 42 and 46 µm posterior to level of anus, at 42 and 48% of tail length. (ref. ID; 7200)

Allotype (male): L=720 µm, a=32, b=4.8, c=8.7, c'=4.9, T=49. Stylet length 14 µm. Body linear, tail strongly curved ventrally. Head hemispherical, with four distinct annules and two apically indistinct annules. Stylet knobs with sloping anterior surfaces. Excretory pore 117 µm posterior to head end, hemizonid 4 µm anterior. Deirids minute, 6 µm posterior of level of excretory pore, at anterior level of basal esophageal bulb. Spicule length 24 µm, gubernaculum 6 µm. Tail conoid, terminus tapering abruptly to a narrowly rounded tip. Bursa narrow, extending only slightly beyond body, margins crenate. Phasmids 33 µm posterior to cloacal opening, at 40% of tail length. (ref. ID; 7200)

Type host and locality

Collected from clay soil substrate at Skeleton Creek, Northwest Territories. Host unknown. (ref. ID; 7200)

Type designations

Holotype (female), type slide No.255, collection No.3056. Allotype (male), type slide No.255a, collection number as for holotype. Deposited in the Canadian National Collection of Nematodes, Ottawa. (ref. ID; 7200)