Difference between revisions of "Notoscolex repanga"
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Ordo: Haplotaxida
Familia: Megascolecidae
Genus: Notoscolex
Name
Notoscolex repanga Blakemore, 2011 sp. n. – Wikispecies link – ZooBank link – Pensoft Profile
Material Examined
Holotype Auckland Museum; AMNZ 5253. Single complete specimen, now dissected, from New Zealand, Cuvier Island (36°26'S, 175°46'E) SE catchment 40–60 m. Coll: 3.IV.2000, J.W. Early & R.F. Gilbert. “Under rock in stream bed. L8229” “W-024” on lid. (Small tissue sample was taken for DNA analysis coded RJB07).
Etymology
After Maori name for Cuvier Island; Notoscolex is treated as masculine but this place name remains genderless as a noun in apposition.
Diagnosis
Notoscolex having spermathecal pores paired posteriorly in 7 and 8 but with clavate spermathecae anteriorly in 8 and 9; holandry with seminal vesicles in 9 and 12; oesophageal gland annular in 12; genital markings mid-ventral in 16/17/18/19.
External characters
Body circular. Pale unpigmented in alcohol. Length 135 mm with 149 segments. Prostomium prolobous. Setae lumbricine, 8 per segment in mostly regular rows and almost equidistant throughout. Clitellum not marked. Dorsal pores present but minute and difficult to detect, possibly commencing from 9/10 or 10/11. Nephropores not found (meroic). Spermathecal pores segmental, posteriorly just above intersegments in setal a lines on 7 and 8. Female pores difficult to detect with certainty, possibly mid-ventral pair anterio-median to setae a on 14. Male and prostatic pores combined on small tumescences on 18 in position of deleted setae a. Penial setae not found. Genital markings mid-ventral eye-shaped sucker pads in 16/17, 17/18 and 18/19; a yellowy midventral patch from ½14-16/17 may be artefactual.
Internal morphology
Septa increasingly thickening from 4/5–10/11; 11/12 thin and thereafter membranous. Gizzard large but weak in 5. Dorsal blood vessel single; commissurals in 5–8; hearts paired and small in 9, much larger in 10–13; supra-oesophageal vessel not found. Nephridia meroic with several avesiculate tubules almost evenly spaced in several rows on body wall in each segment. Spermathecae in 8 and 9 each with saccular ampulla and single, small clavate diverticulum (non inseminated). Holandric: testes and funnels minute in 10 and 11 ventrally; seminal vesicles paired, racemose in 9 and, larger, in 12. Ovaries paired as fine string masses ventrally in 13; ovisacs not found. Prostates flattened, tubuloracemose extending to ca. 24 from small ducts to male pores in 18. Sessile tumidity associated with genital markings internally. Oesophagus large and folded in on itself in anterior in 6–9 at least; with annular dilated oesophageal gland in 12. Intestinal origin in 16. Typhlosole and caeca not found (absent). Gut contains fine silt with few organic fragments. Intestine paler and concertinaed between 35–40 where several (gregarine?) parasitic cysts on stalks attach to it (see figure).
Ecology
Habitat location (under rocks in stream) would indicate an aquatic or semi-aquatic life style, a conclusion supported by the pale colouration plus reduced dorsal pores and gizzard; while the folded oesophagus in the anterior would allow considerable extension (for movement and feeding) and the gut contains silty (alluvial?) soil. Alternatively, this specimen may be an unintentional interloper washed into the stream from adjacent soil; more ecological information is needed to confirm or disconfirm this.
Remarks
Notoscolex is primarily an Australian genus with representatives in Sri Lanka and southern India as well as NZ. The current specimen although large is possibly subadult (it has genital markings but lacks a distinct clitellum and spermathecae uninseminated) yet appears to be a distinct species. Its morphology is comparable to the nine previously known regionally compatriot Notoscolex species, all confined to the north of the North Island, many of which were at some time placed in the cohesive genus Tokea Benham, 1904. This latter genus was made junior synonym of Notoscolex following Michaelsen (1916)[1], Stephenson (1930[2]: 837) and as herein compared to Lee (1959)[3] who placed it within Megascolides.
Of the nine or so New Zealand species now known, Notoscolex repanga differs: from Notoscolex sapidus, Notoscolex urewerae, Notoscolex huttoni and Notoscolex suteri, all by Benham (1904)[4] and each having three pairs of spermathecae; and from Benham’s Notoscolex kirki and Notoscolex maoricus which share two pairs but differ in their arrangements of genital markings and spermathecae. Whereas Notoscolex kirki has intersegmental spermathecal pores in 7/8/9, Notoscolex maoricus has them segmentally but in posterior of 7 and 8, and not 8 and 9 as he originally stated and as inadvertently retained by Lee (1959[3]: 302). [This correction according to Benham (1905: 240, pl XL, figs. 1–2, 8–9) – see http://www.archive.org/stream/transactionsproc38newz#page/240/mode/2up or http://rsnz.natlib.govt.nz/volume/rsnz_38/rsnz_38_00_002970.pdf where he unconventionally records segments 7 & 8 as “7/8” and 8 & 9 as “8/9”; see also http://rsnz.natlib.govt.nz/image/rsnz_38/rsnz_38_00_0736_0000f_ac_01.html for his original figures of Tokea maorica and its junior synonym Tokea decipiens Benham, 1905]. Notoscolex hakeaphilus (Benham, 1949) does have spermathecae in 8 and 9 (with pore locality indeterminate) but differs not least in its large (650 mm) dark body with irregular setae and metandry. Notoscolex napierensis (Benham, 1941) has its four pairs of spermathecal pores equatorial on 6–9, and was probably misdescribed by Benham as having two pairs of tubular prostates on 17 and 19, where the genital markings lie, while Lee (1959[3]: 304), who thought it introduced, accords it a single pair of lobate prostates in 18; dorsal pores were unstated by both authors. A previous Notoscolex member, Notoscolex mortenseni (Michaelsen, 1924) is now moved to Aporodrilus.
Superficially, Notoscolex repanga is somewhat similar to several Megascolides spp., such as Megascolides viridis, Megascolides raglani, Megascolides irregularis, Megascolides alba and Megascolides novaezealandiae, but it differs from all generically by its non-tubular prostates, and specifically by virtue of combination of segmental spermathecal pores and three mid-ventral genital markings, plus an oesophageal gland in 12 only and its last hearts in 13 rather than 12.
A further Megascolides species occurring in NZ and now possibly extinct was described by Schmarda in 1861 under the title of “Hypogaeon orthostichon,” that is subjected to separate treatment in a forthcoming publication (Blakemore submitted.).
Original Description
Other References
- ↑ Michaelsen W (1916) Results of Dr E. Mjoberg’s Swedish Expedition to Australia 1910–1913. Kungliga Svenska Vetenskapsakademie ens Handlingar. 52 (13): 3-74.
- ↑ Stephenson J (1930) The Oligochaeta. Oxford University, Clarendon Press, 978 pp.
- ↑ 3.0 3.1 3.2 Lee K (1959) The earthworm fauna of New Zealand. New Zealand Department of Scientific and Industrial Research Bulletin 130, 486 pp.
- ↑ Benham W (1904) On Some Edible and Other New Species of Earthworms from the North Island of New Zealand. Proceddings of the Zoological Society London, 1904 (2): 220-263. [http://www.archive.org/stream/proceedingsofzoo19042zool#page/240/mode/2up].
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