Gastromermis
Gastromermis Micoletzky, 1925 (ref. ID; 1770)
Family Mermithidae (ref. ID; 1770)
ref. ID; 1770
Diagnosis
Head slightly set off from body, cephalic papillae six, mouth opening terminal, or slightly or strongly ventrally shifted, buccal capsule poorly or well developed. Amphid opening situated posterior to level of cephalic papillae, walls of amphid pouch thick or thin. Vagina long, S shaped, vulval flap present or absent, eggs small, many in several rows in uterus. Tail terminus bluntly rounded. Male with long, slender spicule, genital papillae many and distinct. Tail terminus of male bluntly rounded. Gastromermis was erected first as a subgenus of the genus Paramermis Linstow, 1898 for species with ventrally displaced mouth opening. Filipjev (1934) elevated this subgenus to genus rank without further differentiation. Johnson (1965) considered Gastromermis a subgenus of Hydromermis Corti, 1902. Nickle (1972) placed Paramermis in the categoly of uncertain position and Gastromermis a valid genus on the basis of the male having a long slender spicule. (ref. ID; 1770)
Type species
Gastromermis haempli Micoletzky, 1923 (ref. ID; 1770)
- Gastromermis aquatilis (Hagmeier, 1912) Micoletzky, 1923 (ref. ID; 1770)
- Gastromermis deltensis Hominick & Welch, 1971 (ref. ID; 1770)
- Gastromermis dorsospicularis n. sp. (ref. ID; 1760 original paper)
- Gastromermis haempli Micoletzky, 1923 (ref. ID; 1770)
- Gastromermis leptopeos Mulvey & Nickle, 1978 (ref. ID; 1770 original paper)
- Gastromermis pachopeos Mulvey & Nickle, 1978 (ref. ID; 1770 original paper)
- Gastromermis plethelos Mulvey & Nickle, 1978 (ref. ID; 1770 original paper)
- Gastromermis rosea (Hagmeier, 1912) Micoletzky, 1923 (ref. ID; 1770)
- Gastromermis viridis Welch, 1962 (ref. ID; 1770)
Descriptions
Parasitic in insects; from the haemocoele of chironomid larvae from Portage Creek in the Delta Marsh, Manitoba. (ref. ID; 1770)
Gastromermis leptopeos Mulvey & Nickle, 1978 (ref. ID; 1770 original paper)
Diagnosis
Gastromermis leptopeos n. sp. differs from G. pachopeos n. sp. in having a much thinner spicule head and shaft; the spicule tip of G. leptopeos is also much smaller than that of G. pachopeos, the cuticle width much thinner, and the size and arrangement of the genital papillae significantly different. (ref. ID; 1770)
Descriptions
Male: Head rounded, mouth opening ventrally shifted, vestibulum well developed. Amphid aperture at level of cephalic papillae walls of pouch very thick. Spicule head with characteristic ventral curvature, walls of shaft thin distinctly tapered to acutely pointed tip provided with a pluglike structure. Genital papillae distinct, fairly widely spaced with short inner ducts. Body cuticle thin, faintly striated longitudinally. Tail conoid, bulky, and strongly muscled transversely. (ref. ID; 1770)
Female: Mouth opening slightly to strongly shifted ventrally. Vestibulum well developed. Amphid aperture at level of cephalic papillae, walls of pouch thick. Vulva provided with a large flap, vagina long, S shaped. Eggs tightly packed in uterus in several rows. Tail bluntly rounded. Cuticle at midbody relatively thin. (ref. ID; 1770)
Measurements
Male: body length 9.7(7-13) mm; midbody width 106(95-140) µm; head width 46(38-55) µm; amphid aperture 7-8 µm; amphid pouch 7-8x15-17 µm; spicule length 367(300-430) µm; spicule head width 11.8(10-15) µm; spicule midshaft width 7.2(5-10) µm; tail length 134(100-170) µm; cuticle width at midbody 6.0(5-8) µm. (ref. ID; 1770)
Female: body length 14.4(12-20) mm; midbody width 185(150-260) µm; head width 56(50-64) µm; amphid aperture 7-8 µm; amphid pouch 6-7x13-15 µm; eggs 48-50x45-50 µm (tightly packed in several rows); cuticle width at midbody 9.0(6-10) µm; at level of neck 10(8-15) µm. (ref. ID; 1770)
Gastromermis pachopeos Mulvey & Nickle, 1978 (ref. ID; 1770 original paper)
Diagnosis
Gastromermis pachopeos n. sp. differs from G. leptopeos n. sp. in having a much heavier and thicker spicule shaft and head and spicule tip. The arrangement and size of the genital papillae and the thickness of the body cuticle are sufficiently different to separate the two species. The vestibulum of both Gastromermis leptopeos and G. pachopeos is well developed, which is characteristic of these two species. The vestibulum of G. plethelos n. sp. is poorly developed. Variation in the shape of the spicule head, spicule shaft (tapering or of uniform width and thickness of the walls), the shape and structure of the spicule terminus (tip), the spacing and size of the genital papillae, the size and length of the inner ducts, and the thickness of the body cuticle are all good characters in the identification. The females of G. leptopeos and G. pachopeos differ from all other females in this genus in having a well-developed vulval flap and head characteristic similar to those of the male. The postparasitic male juvenile retains the caudal appendage. The amphid aperture is slitlike with a thick-walled pouch. The vestibulum and spicule are distinct. Post parasitic male juveniles of G. leptopeos, G. pachopeos, and G. plethelos all had short caudal appendages. (ref. ID; 1770)
Descriptions
Male: Mouth opening slightly to strongly ventrally shifted. Amphid aperture at level of cephalic papillae, walls of pouch thick. Vestibulum well developed. Spicule head enlarged, shaft of uniform thickness to a broadly rounded tip provided with a pluglike structure. Genital papillae large, evenly spaced with long inner ducts. Body cuticle very thick, longitudinally striated. Tail bulky with strong transverse musculature. (ref. ID; 1770)
Female: Mouth opening slightly to strongly shifted ventrally, vestibulum well developed. Amphid aperture at level of cephalic papillae; walls of pouch thick. Vulva provided with a large flap, vagina long, S shaped. Eggs many, tightly packed in uterus in several rows. Tail bluntly rounded, cuticle very thick. (ref. ID; 1770)
Measurements
Male: body length 8.2(6.0-12.0) mm; midbody width 140(82-250) µm; head width 52.7(40-60) µm; amphid aperture 7-8 µm; amphid pouch 9-10x15-16 µm; spicule length 436(280-550) µm; spicule head width 28.2(20-40) µm; spicule midshaft width 16.5(10-22) µm; tail length 189(130-250) µm; cuticle width at midbody 13.6(7-21) µm. (ref. ID; 1770)
Female: body length 13.7(12-16) mm; midbody width 202(110-260) µm; head width 64(50-80) µm; amphid aperture 8 µm; amphid pouch 7-10x12-14 µm; eggs 42-50x40-48 µm (tightly packed in several rows); cuticle width at midbody 18.0(15-22) µm; at level of neck 19.8(17-24) µm. (ref. ID; 1770)
Gastromermis plethelos Mulvey & Nickle, 1978 (ref. ID; 1770 original paper)
Diagnosis
Gastromermis plethelos n. sp. differs significantly from Gastromermis leptopeos n. sp., and Gastromermis pachopeos n. sp. in having a terminal mouth aperture and poorly developed vestibulum versus a slightly to strongly ventrally shifted mouth aperture and a well-developed vestibulum in the latter two species. In addition the structure and position of the amphid and the shape and structure of the spicule tip are much different. (ref. ID; 1770)
Descriptions
Male: Mouth opening terminal vestibulum poorly developed. Amphid aperture well posterior to level of cephalic papillae, walls of pouch thin. Spicule head flared, walls of shaft of medium thickness, shaft of uniform width to broadly rounded spicule tip. Genital papillae very closely spaced with short inner ducts. Body cuticle of medium thickness and distinctly striated longitudinally. Tail fairly long uniformly conoid to rounded terminus. (ref. ID; 1770)
Female: Not found. (ref. ID; 1770)
Measurements
Male: body length 13.0(8.5-16.0) mm; body width 114(100-134) µm; head width 54(50-60) µm; amphid aperture width 9.5(8-10) µm; amphid pouch 10-11x12-13 µm; spicule length 403(350-490) µm; spicule head width 21.7(15-30) µm; spicule midshaft width 10.9(10-14) µm; tail length 207(180-250) µm; cuticle width at midbody 10.7(9-15) µm. (ref. ID; 1770)
Descriptions
Parasitic in insects; from the haemocoele of black fly (Simulium vittatum Zett) from Black Earth Creek, Dane County, Wisconsin, USA, and Number Ten Creek, Hastings County, Ontario. (ref. ID; 1770)