4. Amynthas gracilis (Kinberg, 1867)

(Figures 1 C, 10)

Nitocris gracilis Kinberg, 1867: 102 .

Pheretima hawayana (Rosa, 1891) — Gates 1937: 354; 1954: 229; 1958: 31; 1963: 13; 1982: 47.

Amynthas gracilis — Sims & Easton 1972: 235.

Amynthas hawayanus — Sims & Easton 1972: 235. Reynolds 1978: 121, 127; 2010: 145; 2011: 271. Reynolds & Wetzel 2004: 88; 2008: 179.

Data sources. Gates (1937, 1972, 1982); Blakemore (2013a).

Diagnosis. Size 56–156 mm by 3–6 mm. Segment numbers 70–101. Color of live specimens red. Male pores paired in XVIII, small, superficial, on a small porophore. Post-clitellar genital markings present or absent; when present, paired post-setal small discs median to male pores, in tight clusters of 1–11. Spermathecal pores three pairs in 5/6/7/8. Pre-clitellar genital markings present or absent; when present, paired post-setal small discs median to spermathecal pores on some of VI–IX. Female pore single in XIV. First dorsal pore 10/11 or 11/12. Spermathecae three pairs in VI–VIII, duct slender, as long as or shorter than ampulla, with a tubular diverticulum shorter than the main axis. Prostate glands well developed, extending through some or all of XVI–XXIV. Intestinal caeca paired in XXVII, simple, extending anteriorly to XXIV.

Remarks. Historically referred to as Pheretima hawayana or Amynthas hawayanus, A. gracilis has been frequently reported in the US. The first record of this species in the continental US was in 1905 in Illinois (Gates 1937; 1954; 1982). Reproduction of A. gracilis is amphimictic. A. gracilis, an epi-endogeic species, has been suggested to increase C and N flux in forest soils in northeastern US and may have potential long-term impacts on nutrient cycling (Burtelow et al. 1998).