Maoridrilus felix 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 : 23

Maoridrilus felix Blakemore sp. nov.

Material examined. Museum of New Zealand Te Papa Tongarewa W.002908 (Holotype). From the tussock grassland of ‘Happy Valley’ (Upper Waimangaroa Valley, Buller Region, West Coast, New Zealand). Collected by S. Boyer, 2010. Mature, complete, fixed in ethanol 98% and placed in propylene glycol.

Etymology. Adjectival Latin for “Happy”, after the location name.

External characters. Body circular in anterior, squaring off in mid-body and dorsally canaliculate in the posterior 50 or so segments. Pigment dark, especially dorsum chocolate brown with darker mid-dorsal stripe. Length 170 mm with 199 segments. Prostomium tanylobous. Setae lumbricine. Clitellum faintly marked 15-19,½20. Dorsal pores wanting. Nephropores, after the first few segments, alternate regularly between c and b lines with anterior segmental distributions: 3–7c, 8 c or b, 9–10c, 11b, 12c, 13b, etc. Spermathecal pores in mid-ab lines in 7/8 and 8/ 9. Female pores faint, just anterior to b setae on 14. Prostatic pores approximately in a lines on 17 and 19 with protuberant penial setae. Male pores not located within concave seminal grooves, although likely central between retained ab setae. Genital markings absent, but setae ab on 16 with slight pale tumescence as on 20lhs. Genital setae absent; penial setae longish, curving with spoon-shaped tips [one of their functions, if not primary function, is to scrape out or disrupt any prior semen from spermathecal diverticula that often correspond in depth to the setal length (see Blakemore 2000)].

Internal morphology. Pharyngeal mass anterior to 4/5. Septa mostly thin and translucent. Proventriculus wide and S-shaped in 5. Gizzard muscular in 6. Dorsal blood vessel single thoughout. Heart paired in 10–13. Nephridia holoic with long, sausage-shaped vesicles. Spermathecae in 8 and 9 each with a multiloculate diverticulum (inseminated) transcending anterior septum. Testes free, posterio-ventrally in 10 and 11. Seminal vesicles saccular, anterio-dorsally in 11 and 12. Ovaries compact sheets in 13 with large oviducts; ovisacs not found. Prostates tubular in 17 and 19 exiting through muscular ducts with ectal penial setal sheathes and tendons. Vasa deferentia seen to 18. Oesophagus dilated in 11–15 with blood vessels attaching dorsally but not saccular and not construed as calciferous glands. Intestinal origin in 18. Typhlosole not detected to about 26. Gut contains colloidal organic matter.

Ecology: Lack of dorsal pores is more usually associated with a semi-aquatic habitat. Unidentified nematodes were found near the prostates (cf. Yeates et al., 1985). Specimen was found under 10 to 20 cm of soil. Dark colouration on the dorsum suggests at least partial surface exposure on topsoil, gut content suggests topsoil geophagy. This species is likely to be anecic.

Remarks. Quintessentially Maoridrilus due to its alternating nephridiopores, this species appears unique in its lack of dorsal pores (although more information is needed on several other congeners), gizzard in 6, lack of oesophageal glands, and genital marking absence. Multiloculate spermathecae appear characteristic of the genus and in the current species their form is almost identical to Maoridrilus thomsoni Benham, 1919 : fig. 4 from D’Urville Island in Cook Strait. Lee (1959) held this species, along with similar M. intermedius Michaelsen, 1923 and M. mauiensis Benham, 1904 , as incertae sedis because original descriptions were inadequate. Permanence of the name M. felix depends on redescription of M. thomsoni , however, the manifestly larger penial setae and lack of oesophageal glands in 14–16 seem to separate the current species. Maoridrilus nelsoni Lee, 1959 differs in its prostatic pores in b lines, and its prominent tuberculae pubertatis ventrally on segments 10 and 16. Maoridrilus uliginosus (Hutton, 1877) differs, not least, in its paired dorsal blood vessel.