Benham - North Island Earthworms - RSNZ
In general appearance this worm might readily be mistaken, at least in the preserved condition, for R. besti, from which however, it presents certain well-marked differences. I received about twenty specimens.
Colour - white, with pale yellow clitellum
Dimensions - mature worms measure from 140 - 165mm by 5mm, with about 200 segments, which, with the exception of the first six or seven, are annulated, whereas in R. besti the annulation commences on the 5th segment.
Chaetae - In the midbody ab = bc = cd, approximately (but just behind the clitellum bcbc is about 2ab); aa > bc; and dd = 6ab. As is usual in the genus, the two chaetae a,b begin to approach one another at about the 25th segment, so that in the region of the male pores the couple are quite close together, but they separate again anteriorly.
The clitellum, (half 13) 14 - 17, is complete only across 14.
Genital pores, etc. - the male pores, in line with ab, are on slight papillae. The tubercula pubertatis have rather an unusual appearance: each is a trnasverse group or series of glands, visible under a dissecting-lense as a series of translucent dots set on a slightly raised ridge. These tubercula are in the following groups:-
(1.) A pair on the intersegmental furrow 10/11, inline with ab.
(2.) Two transverse series, 14/15 15/16 extending from the line a to a.
(3.) Two to four post-clitellar intersegmental series, 19/20 20/21 21/22 22/23 of these the most anterior extends from b to b, the last from a to a.
Of the seven mature individuals examined, one specimen alone had four post-clitellar tubercules, three had three, and three had only two tubercles. There is a single pair of spermathecal pores nearly in line b, between segments 8/9.
Internal Anatomy.- The last heart is in segment 12. The gizzard is in segment 5. Theintestine commences in the 16th. There are no oesophageal glands. The sperm sacs are, as usual, in segments 11/12. The prostates extend along the sides of the body to segment 21 or 22, being sharply undulating in the last two segments. The duct is very narrow, quite short and straight.
The penial chaetae (and the sacs containing them) are very short, and confined to the 17th segment. The chaetae measure only 2mm., which is a great contrast to the length of 6mm. attained by them in R.besti. Each chaetae is simply curved, ending in an apparently flexible recurved tip. The shaft for some distance below the tip is "ornamented" in a very characteristic fashion; under a low power it appears serrated along each edge but under a higher power it is seen to be pitted all round. The pits are oblique, with openings distally directed, leaving distally directed proximal edges.
The spermatheca, in segment 9, consist of a short ovoid sac lying on the outer side, and a long cylindrical portion, curved in a semi-circle, towards the median line.
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