Aporodrilus aotea, Blakemore, Robert, 2011

Blakemore, Robert, 2011, Further records of non-cryptic New Zealand earthworms, ZooKeys 160, pp. 23-46 : 27

Aporodrilus aotea sp. n. Fig. 1

Material Examined.

Holotype Auckland Museum; AMNZ 5254. Single complete specimen, now dissected, from New Zealand, Great Barrier Island, Little Windy Hill (ca. 36°10'S, 175°23'E). Coll: 2.IX.2001, J.W. Early & R.F. Gilbert. "Under rock on forest floor. L11002". “W-025” on lid. (Small tissue sample was taken for DNA analysis - code RJB09).

Etymology. After Maori name for Great Barrier Island; Aporodrilus is treated as masculine but this place name remains genderless as a noun in apposition.

Diagnosis. Aporodrilus having spermathecal pores paired segmentally in 6, 7 and 8; holandry with seminal vesicles in 9 and 12; oesophageal glands annular in 10-14; large genital markings paired in 17/18 and 18/19 on either side of male pores.

External characters.

Body circular tapering at both ends. Dark, matt grayish pigment with iridescent cuticular sheen; paler intersegments and setal auriolae. Length 140 mm with 75 segments. Prostomium epilobous. Setae lumbricine, 8 per segment in rows becoming increasingly irregular further back. Clitellum not well marked. Dorsal pores absent. Nephropores not found (meroic). Spermathecal pores segmental, equatorial just below setae a on 6, 7 and 8. Female pores mid-ventral pair anteriormedian to setae a on 14. Male and prostatic pores combined on tiny mounds on 18 in position of deleted setae a. Penial setae not found. Genital markings large, longitudinally symmetrical pads, paired in 17/18 and smaller in 18/19.

Internal morphology.

Pharyngeal mass to 4. Septa 4/5-10/11 thin, only 11/12/13 with slight thickening and thereafter membranous. Gizzard strong and elongate apparently in 6-7 but discernable in 5 by tracing septum 5/6 to near base despite dorsal-wards displacement. Dorsal blood vessel single; hearts paired and increasingly large in 9-13; supra-oesophageal vessel in 10-13. Nephridia meroic with forests of avesiculate tubules on body wall. Spermathecae in 7, 8 and 9 each with elongate, flaccid ampulla and single, small, clavate diverticulum (inseminated) near base implicated with anterior septum which is transgressed. Holandric: minute funnels in 10 and 11 ventrally; seminal vesicles paired, racemose posteriorly in 9 and anteriorly in 12. Ovaries paired as free egg-string bunches ventrally in 13; ovisacs not found. Prostates tubuloracemose extending to ca. 22 from small flaccid ducts to male pores in 18. Oesophagus with oesophageal glands small in 10 and larger in 11-13 then small again in 14; glands more saccular than composite but dilated compared to extraneous oesophageal width. Intestinal origin in 16. Typhlosole and caeca not found (absent). Gut contains fine colloidal reddish soil.

Ecology.

Lack of dorsal pores is usually associated with aquatic habitat, but possibly also with high rainfall/soil-moisture, however, the strong gizzard suggests a loamy diet. Further ecological and/or behavioural information is wanting.

Remarks.

Aporodrilus aotea compares with Aporodrilus mortenseni (Michaelsen, 1924) that differs, not least, by having its three pairs of spermathecal pores intersegmental in 6/7/8/9 and by lacking genital markings. However, in the review by Lee (1959) that did not routinely note presence or absence of dorsal pores (nor genital markings), the current species keys out nearest to Lee’s Megascolides species now in Notoscolex , viz.: Notoscolex sapidus that differs in its spermatheal pores intersegmental in 6/7/8/9; or to those now in Aporodrilus viz. Aporodrilus equestris (Benham, 1942), and edible Aporodrilus esculentus (Benham, 1904) with which it perhaps comes closest as this too has spermathecae opening on 6-8. Aporodrilus equestris as redescribed below has genital markings elongate in 17 & 19, exceptionally thickened septa, a gizzard in 6 and intestine from 17; while Aporodrilus esculentus has genital markings paired midventrally in 16 and 17, thicker septa, a smaller gizzard, oesophageal dilations only in 15 and its spermathecae of a more spherical and compact form (see figures and compare Benham’s original sketches http://www.archive.org/stream/proceedingsofzoo19042zool#page/240/mode/2up). A more distant contender is Notoscolex urewerae (Benham, 1904) "a short white worm" that has genital marking mid-ventrally in 19/20 and last hearts in 12 amongst other differences (its dorsal pores are unrecorded and possibly it too belongs in Aporodrilus ).