Deinodrilus gorgon Blakemore

Boyer, Stephane, Blakemore, Robert J. & Wratten, Steve D., 2011, An integrative taxonomic approach to the identification of three new New Zealand endemic earthworm species (Acanthodrilidae, Octochaetidae: Oligochaeta), Zootaxa 2994, pp. 21-32 : 24

Deinodrilus gorgon Blakemore sp. nov.

Material examined. Museum of New Zealand Te Papa Tongarewa W.002909 (Holotype). From the tussock grassland of “Happy Valley” (Upper Waimangaroa Valley, Buller Region, West Coast, New Zealand). Collected by S. Boyer, 2010. Mature, posterior amputee, fixed in ethanol 98% and placed in propylene glycol.

Etymology. Noun alluding to Greek mythical monsters with sharp fangs, staring eyes and, similar perhaps to the ring of diverticula on each spermatheca – a belt of serpents.

External characters. Body circular in anterior. Pigment dark, especially dorsum with paler setal auriolae; clitellum and male field white. Length 55+ mm with 73+ segments (amputee). Prostomium tanylobous. Setae perichaetine, 12 per segment, evenly spaced. Clitellum pale, tumid ½13–16. Dorsal pores from 10/11. Nephropores not found. Spermathecal pores in b lines in 7/8 and 8/9, small but gaping. Female pores anterio-ventral to a setae on 14 in common field. Prostatic pores at b on 17 and 19. Male pores within concave seminal grooves lateral to b. Genital markings as large eye-shaped papillae paired on 10; with smaller markings on 13rhs, 16 rhs and two additional pairs on 18 as figured. Genital and penial setae not found.

Internal morphology. Pharyngeal mass anterior to 4/5. Septa 8/9–10/11 with some thickening. Gizzard muscular in 6 (weak septum 6/7 can be carefully teased off to base). Dorsal blood vessel doubled. Heart paired in 10– 13. Nephridia meroic; equatorial forests especially obvious around clitellar segments. Spermathecae in 8 and 9 each with a thin duct to multiple, finger-like diverticula, five per spermatheca (inseminated) surrounding duct from where it thickens before reaching yellowish, knob-like ampulla. Testes free, posterio-ventrally in 10 and 11. Seminal vesicles small saccular in 9 (vestigial?) and larger racemose anterio-dorsally in 11 and 12. Ovaries fan-shaped in 13 with several strings of largish eggs; ovisacs vestigial in 14. Prostates compacted tubular in 17 and 19 exiting through muscular ducts. Vasa deferentia seen to exit unceremoniously in 18. Oesophagus dilated in 15–17 but lacking internal lamellae and thus not construed as calciferous glands. Intestinal origin in 18. Typhlosole thin, lamellar becoming deeper from 19. Gut contains colloidal soil and organic matter.

Ecology. Specimen was found under 10 to 20 cm of soil. Dark colouration suggests at least partial surface exposure on topsoil, gut content suggests topsoil geophagy. This species is likely to be anecic.

Remarks. Of the eight currently known Deinodrilus species, only two have tanylobous prostomia: D. gracilis Ude, 1905 from Stephen Island and D. parvus Lee, 1959 from Mangamuku Range. Both also have 5 or 6 spermathecal diverticula however, D. gracilis has copulatory setae, oesophageal glands and intestine from 19; while D. parvus has a saddle-shaped clitellum in 12–16, and all its reproductive pores are in a or ab. Further, their gizzards are in 6–7 and 5, respectively, rather than single in 6 as in the current species. D. montanus Lee, 1959 from Rimutaka Range is similar to D. parvus and differs for similar reasons. The current species appears unique in the distribution of its eye-like genital markings that are especially noticeable on segment 10.