Aporodrilus ponga, Blakemore, Robert, 2011

Blakemore, Robert, 2011, Further records of non-cryptic New Zealand earthworms, ZooKeys 160, pp. 23-46 : 28-30

Aporodrilus ponga sp. n. Fig. 2a2b

Material Examined.

Holotype Auckland Museum; AMNZ 5255. Single mature, posterior amputee rather poorly preserved from Waitakere Ranges, Waiatarua. Coll: 9.V.1995, G. Ripley. "Nikau/Ponga forest L761"; “W-012” on lid. (Small tissue sample was taken for DNA analysis coded RJB10). [Two other specimens from the same jar are a posterior portion of a worm (AMNZ 5256) matching the dimensions and frayed edge of the current specimen is itself missing its tip; the other (AMNZ 5254) is a large mature, anterior amputee that is certainly different and probably a new species but which is inadequate for formal description here].

Etymology.

After Maori name for silver fern Cyathea dealbata (G. Forster) Swartz, 1801, from the habitat detail and also the symbol commemorating the All Blacks victory in 2011 Rugby World Cup; Aporodrilus is masculine, but a noun in apposition is genderless.

Diagnosis.

Aporodrilus having spermathecal pores paired intersegmentally in 7/8/9; metandric with seminal vesicles in 12; no oesophageal glands; genital marking as a distinct pad in 17/18 with male pores on lower rim replacing setae a.

External characters.

Body robust, dorsally canaliculated in parts before amputation. Pale putty coloured in alcohol. Length 220+ mm anterior portion (a posterior fragment in jar is also 220mm and if from same specimen would give length = 440 mm). Prostomium much wrinkled prolobous. Setae lumbricine, obscure in anterior and mostly occluded on clitellum apparently converging towards male pores; further back the rows except for setal a lines become progressively irregular. Clitellum slightly more tumid and yellowy in ½13– 17 (or thereabouts). Dorsal pores absent. Nephropores absent (meroic). Spermathecal pores intersegmental, detected by probe from interior and approximately in setal a lines in 7/8/9. Female pores large paired on 14 (setae obscure) in line with setae a of 13. Male pores superficial on 18 in place of deleted setae a on bottom rim of pad (detected by probe internally). Penial setae not found. Genital marking as a large pad in 17/18 distending both adjacent segments.

Internal morphology.

Septa and pharyngeal mass absent before 5, septa 5/6-12/13 greatly thickened, thereafter membranous. Gizzard mucular barrel in 5. Dorsal blood vessel single; hearts sinuous in 9-13. Nephridia meroic forests on body wall. Spermathecae paired in 8 and 9 each with flask-shaped ampulla on equally long flat duct with multilocular diverticular frill (inseminated) near base. Probably metandric as paired seminal vesicle seen in 12 only. Testis and ovaries not located, probably minute and lost in musculature of septa and body wall. Prostates rounded but finely incised throughout so not as found in Acanthodrilidae and Octochaetidae (cf. Exxidae ), i.e. tubuloracemose with small flaccid ducts in 18. Oesophagus without noticeable dilations (what I initially took as a hemispherical thickening of posterior of 9 was determined as a septum). Intestine substantial yet dilated and easily ruptured, origin appears in 15 or 16. Gut contains finely ground organic matter, organic soil plus coarse multi-coloured grits.

Ecology.

Anterior musculature and thickened septa are associated with strong burrowing, and lack of (anterior) dorsal pores may aid maintenance of hydroskeletal turgor pressure.

Remarks.

Aporodrilus ponga differs from Aporodrilus aotea on almost each specific point. According to Lee (1959), who often took tubuloracemose prostates to be tubular, this specimen keys to genus Megascolides but fails to match any known taxa from there. If more properly allowed into Lee’s Notoscolex the similarity with Notoscolex hakeaphilus Benham, 1949 is remarkable: viz. large size (650-950 mm) with irregular setae, male pores on a median oval depression, septa absent before 5, spermathecae in 8 and 9, and metandry. Presumed differences however, are darker colour (current specimen bleached in alcohol?), epiloby and again much furrowed as here, tufted nephridia (how tufted?) in anterior, a thick-walled enlargement of oesophagus in 8 (possibly as I initially thought was in 9), prostates claimed as flat rather than rounded (although figured as rounded), spermathecae with "a minute globular diverticulum" (variation?), and male pores shown laterally within pad on 18 rather than on its rim as here. It is possible Benham mistook some of these points. His report of last hearts in segment 10 for this species is undoubtedly anomalous as invariably they are in either segments 12 or 13 in normal Megascolecidae ; and intestine in 12 is also anterior to what is usual. No mention was made of dorsal pores by him. Benham’s type was collected in 1946 from Kerikeri (A.48.31 - supposedly in poor condition but confirmation from Otago museum unforthcoming) that he thought imported from Australia as was the plant it was found under. This seems unlikely for such a large species: even if its cocoons were introduced, large species often have particular habitats unlike most small to medium cosmopolitans. Lee (1959: 318), presumably accepting Benham’s characterization, has another specimen (current location unknown) from Pukehohe, suburb of Auckland, from subsoil collected by W. Cottier in 1951. (An online GBIF record of Australian Museum AM W.29352 at Taupo is unconfirmed http://data.gbif.org/occurrences/237279142 accessed November, 2011). A much smaller species but with remarkable superficial similarity of marking to Benham’s Notoscolex hakeaphilus is his Notoscolex maoricus (Benham, 1904) (syn. Tokea decipiens Benham, 1905) that also comes from " Waitakerei Bush " (= Waitakere), near Auckland.

Without information to the contrary we must reluctantly accept the balance of Benham’s earlier diagnosis, in which case a new name for this specimen has merit. Confirmation of independence of either species now depends on reinspection of Benham’s type, apparently beyond the brief, budget and resources of successive workers for the last 62 years, including the present one.