Cambridgea decorata
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Name
- Cambridgea decorata Blest & Vink, 2000
Notes
This species is problematic. It was described by Blest & Vink (2000: 17) from specimens in suboptimal condition collected in the 1940's from Parnell (male holotype) and nearby Waiheke Island (females). No other specimens have been reported. The original description is brief. Most of it is measurements, but these probably aren't of much diagnostic value. The male palpal tibial apophysis and female epigynum are illustrated, but not described in any way. The legs are described as 'brown, not annulated'. The chelicerae are described as 'Paturon 4.20. Retrolateral teeth: 2 large, medial. Prolateral teeth: all basal, 1 medium, 2 large, 3,4 medium'. Apart from some vague description of the colour pattern (in addition to that of the legs, quoted already above), that is the entirety of the original description. The species is placed in a group with C. plagiata and C. mercurialis. The male palpal tibial apophyses and female epigynes were illustrated for all three species, the former showing some variation in C. plagiata.
I have examined a good series of both sexes of a Cambridgea species, collected from pitfall traps at Maungatautari Mt. (WO), by C.H. Watts. I believe these to be C. decorata. The epigynum is a little variable, sometimes resembling that illustrated by Blest & Vink (2000: 18, fig. 44) for C. plagiata, but mostly resembling more that illustrated by them (fig. 46) for C. decorata. In the gallery below, I have illustrated an epigynum which pretty much exactly matches fig. 46, except just for the lack of the pair of pits that are somewhat vaguely indicated on fig. 46. The epigynes are not two dimensional in reality, so orientation is important to consider when interpreting the figures. I am not entirely convinced that figs. 44 and 46 show differences that cannot be explained away by orientation and/or variation, so it is possible that C. decorata will turn out to be a synonym of C. plagiata. At any rate, the main problems are that, firstly, the males associated with the females on Maungatautari have palpal tibial apophyses (see image below) which better match fig. 47 (C. mercurialis), and not fig. 45 (C. decorata). Secondly, legs 2-4 of the Maungatautari specimens are annulated. This may not have been evident on the old and faded specimens examined for the original description of C. decorata. Thirdly, although the prolateral teeth of the Maungatautari specimens agree well with the original description, it is unclear if the retrolaterals are "medial" or "distal".
More research is needed to solve this puzzle. One possibility is that the unassociated male holotype of C. decorata has been incorrectly associated with the Waiheke Island females, so the latter are not C. decorata, but probably either a new species, or C. plagiata. This would leave C. decorata known only from the male holotype collected in Parnell in 1947, though it could possibly be just an aberrant specimen of C. plagiata.
Given the variability in male palpal tibial apophyses for C. plagiata, plus the variation in epigynes of the Maungatautari specimens, there is very little to distinguish C. decorata from C. plagiata. Perhaps the internal female genitalia may be significant (though the holotype of C. plagiata is a male)? C. plagiata was not fully redescribed by Blest & Vink (2000), and the original description by Forster & Wilton (1973: 149) is a little bit vague in some key places. They say 'legs banded', and '[cheliceral] retromargin with two teeth. Promargin with five teeth'. The promargin of C. decorata (types and Maungatautari specimens) have only four teeth, but one Maungatuatari specimen I have seen had an extra retromarginal tooth on one side, so there may be some variability, and nothing was specified about the relative sizes of the five teeth, so one tooth could perhaps be very small and easily overlooked. At any rate, an extra promarginal tooth is probably not significant enough by itself to hang a species distinction on.
References
- Blest, A.D.; Vink, C.J. 2000: New Zealand spiders: Stiphidiidae. Records of the Canterbury Museum, 13(supplement)
- Forster, R.R.; Wilton, C.L. 1973: The spiders of New Zealand. Part IV. Agelenidae, Stiphidiidae, Amphinectidae, Amaurobiidae, Neolanidae, Ctenidae, Psechridae. Otago Museum bulletin, (4)
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