A new species of the Amynthas corticis group with support from mitogenomic data and a new record of Metaphire agrestis (Goto & Hatai, 1899) (Oligochaeta, Megascolecidae) in northeastern China Author Han, Anne Charis N. https://orcid.org/0009-0000-7312-4985 Hebei Key Laboratory of Animal Diversity, College of Life Science, Langfang Normal University, Langfang 065000, China & State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China Author Zhao, Nannan https://orcid.org/0009-0005-4694-3121 Hebei Key Laboratory of Animal Diversity, College of Life Science, Langfang Normal University, Langfang 065000, China Author Aspe, Nonillon M. 0000-0003-0025-6017 College of Environment and Life Sciences, Mindanao State University at Naawan, Misamis Oriental, Naawan 9023, Philippines Author Nob, Christian Jay R. 0000-0003-2463-6698 State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China Author Zhang, Yufeng 0000-0002-4066-6355 Hebei Key Laboratory of Animal Diversity, College of Life Science, Langfang Normal University, Langfang 065000, China Author Wu, Donghui 0000-0001-8778-0107 State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China & Key Laboratory of Wetland Ecology and Environment, State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China Author Zhao, Huifeng 0000-0003-4243-9671 Hebei Key Laboratory of Animal Diversity, College of Life Science, Langfang Normal University, Langfang 065000, China & Key Laboratory of Wetland Ecology and Environment, State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China text ZooKeys 2026 2026-01-12 1266 231 261 journal article 313703 10.3897/zookeys.1266.161903 7f572354-0167-4afa-a8ee-1c0d01077429 3A9374B8-02B0-4BFC-BF13-CA86BC51B6C4

Table 4. Comparison of characters among M. agrestis (Goto & Hatai, 1899) from Japan, South Korea, North America, and China.

Species	Perichaeta agrestis (original description)	A. agrestis	A. agrestis	A. agrestis	M. agrestis
Source	Goto and Hatai 1899	Chang et al. 2016	Reynolds 2023	Blakemore 2013	this study
Locality	Japan	USA	Canada	Korea	Northeast China
Length	100–160	70–160	70–200	100–140	80–94
Segments	80 – 96	63–110	67–110	105	100–108
diameter	5 – 8	5–8	5–8		5–8
1 st dorsal pore	11 / 12 or 12 / 13	12 / 13	12 / 13	11 / 12 or 12 / 13	12 / 13
Setal number	36 (spermathecal region), 40 + (more posteriorly)				36–40 (V), 52–65 (VII), 55–72 (VIII)
Spermathecal pores	three pairs, in 5 / 6 / 7 / 8	three pairs, in 5 / 6 / 7 / 8 or variously missing	minute and superficial in 5 / 6–7 / 8, ~ 1 / 3 circumference (C) apart	three pairs, in 5 / 6 / 7 / 8	three pairs, in 5 / 6 / 7 / 8 (0.28–0.30 C apart ventrally)
Male pores	absent	usually absent; when present, small, transversely slit-like	absent; when present minute and located on an eversible papilla	absent	absent
Pre-clitellar genital markings	absent, however, there are two pairs of slightly elevated squarish patches of a pale brown color inside the spermathecal pores, one in VII and the other in VIII	absent; when present, ventral, areas of slight epidermal modification on VII and / or VIII, unpaired and median or symmetrically paired, forming setal gaps	usually lacking	dark patches on elongate on VII and paired in VIII in some specimens	absent, however a slightly pale brown patch around the midventral area of the spermathecal pores
Post-clitellar genital markings	absent	usually absent; when present, single, large circular pad, pre-setal on XVIII, median to male pores	a pair of large presetal papillae in 18 (0.8–1.8 mm in diameter), median to the male porophores	absent	absent
Spermathecae	three pairs in VI – VIII	present or absent; when fully present, three pairs in VI – VIII	three pairs in VI – VIII		three pairs in VI – VIII
Ampulla and duct		duct shorter than ampulla	dorsoventrally flattened with thin wall and numerous wrinkles; duct with thick wall, shorter than ampulla		ovate, surface flattened and wrinkled, (1.5–1.8 mm); duct long, stout, (1.1–1.3 mm)
Diverticulum	diverticula longer than the main sac, but almost straight or very slightly winding	diverticulum longer than duct and ampulla combined.	longer than the main pouch, with sausage-shaped seminal chamber		longer than the main pouch; stalk slender with a swollen long receptacle
Prostate glands	absent	present or absent; extending through some or all of XVI – XXIII	usually absent, but when present in XVI – XX only when male terminalia are present	absent	absent
Seminal vesicles			in XI and XII, filling coelomic cavities of those segment	large in XI and XII	large in XI and XII
Hearts			XI – XIII
Intestines	XV
Gizzard	VIII – IX				VIII – IX
Intestinal caeca	manicate, paired in XXVII bearing seven secondary caeca, the dorsal most being the longest reaching to XXIV		manicate, paired in XXVII and extending anterior to XXIV, with six to nine secondary caeca, the dorsal most being the longest	manicate; paired in XXVII
Accessory glands	absent		low and confined to or extending only slightly above the parietes