Rhampsinitus nubicolus Lawrence 1963

Taylor, Christopher K., 2017, Notes on Phalangiidae (Arachnida: Opiliones) of southern Africa with description of new species and comments on within-species variation, Zootaxa 4272 (2), pp. 236-250 : 244-246

Rhampsinitus nubicolus Lawrence 1963

Figs 4 , 5 b.

Rhampsinitus nubicolus Lawrence 1963: 303 –304, fig. 13a.

Rhampsinitus flavobrunneus Staręga 2009: 45 –47, figs 1–5 syn. n.

Material examined (all CAS). SOUTH AFRICA: 1 major male , Ceylon Forest, W of Sabie , Mpumalanga, 25°05’S 30°42’E, el. 1100 m, indigenous forest, 4.xiii.1996, C. E. Griswold; 5 major males, 6 females, 1 juvenile, Mariepskop, ca . 15 km W Klaserie , Mpumalanga, 24°33’S 30°53’E, el . 1365 m, indigenous forest, 5.xii.1996, C. E. Griswold; 2 major males, 1 female, Mariepskop State Forest, Drakensberg, 5 km N Mariepskop Chalets ( Ranger Station ) , Mpumalanga, 1900 m, montane aloe scrub, 14.x.1999, D. Ubick, S. Prinsloo; 5 major males, 5 minor males, Misty Mountain Hotel, ca . 32 km E Lydenberg , Mpumalanga, 25°10’S 30°40’E, el. 1890 m, in forest, 3– 5.xii.1996, C. E. Griswold.

Description. Major male as described by Staręga (2009; see comments below). Minor male (figs 4a, c, e–h). Body ovate; length 4.63–5.35. Carapace width 2.51–2.80, with scattered denticles including single median denticle on anterior margin, and transverse rows of denticles across mesopeltidium and metapeltidium. Eyemound with three or four pairs of large denticles. Opisthosomal surface granulate; tergites with transverse rows of denticles; posteriormost tergites with minute setae only. Venter mostly unarmed, with black setae; setae on coxae I and II raised on nodules. Chelicerae (fig. 4c) short, robust, length of first segment 1.03–1.40, second segment 2.05–2.83; first segment with scattered denticles dorsally and ventrally, largely unarmed laterally; second segment unarmed with scattered black setae. Pedipalp length of femur 1.77–2.93, patella 0.78–0.94, tibia 1.04–1.42, tarsus 2.15– 2.87; cluster of prominent bristle-bearing nodules on pedipalpal coxa directly below insertion of trochanter; numerous denticles dorsally and ventrally on trochanter and femur; remaining segments unarmed; patella without distinct apophysis; numerous black setae present along entire length of pedipalp, plumose setae absent; microtrichia present on entire length of tibia and tarsus. Legs long, BLI 1.95–2.16, with denticles on anterior and posterior faces of trochanters, longitudinal rows of denticles on femora; leg I with ventral longitudinal rows of small denticles from patella to metatarsus; remaining legs with ventral longitudinal row of small denticles proximally on tibia; remaining leg segments unarmed except ventral pairs of spine-like setae at distal margins of metatarsal and tarsal pseudosegments; femora and tibiae with pseudosegments absent. Length of femur I 5.42– 5.65, femur II 9.45–10.43, femur III 5.34–5.54, femur IV 7.26–7.79. Penis (figs 4d–f) with hatchet-shaped glans, distal profile acute, point of reflexion of posterior margin in lateral view in proximal half; shaft flattened, broadening towards distal end to form distinct ‘spoon’ with markedly sclerotised margins, base moderately bulbous.

Female (fig. 4i) as above, except: Chelicerae both segments unarmed with scattered black setae. Pedipalp femur with black setae on raised nodules proximoventrally, pedipalp otherwise unarmed. Legs I with longitudinal rows of denticles from femur to tibia, denticles becoming minute on tibia.

Notes. Lawrence (1963) described Rhampsinitus nubicolus from Mariepskop in what is now Mpumalanga province. The major males examined herein resemble his description in most particulars, including the arrangement of denticles on the second cheliceral segment and the extraordinarily long pedipalps, the femora of which may be up to 1.4× as long as the main body. They differ in being more noticeably denticulate on the pedipalpal femur which was originally described as ‘smooth except for a few minute spiculiform granules on ventral side’. Nevertheless, there can be little question that these specimens represent Lawrence’s original species. This appears to be a primarily montane species, with all known specimens collected at altitudes above 1000 m.

The specimens examined herein also correspond closely with Staręga’s (2009) description of Rhampsinitus flavobrunneus , and the two species are synonymised herein. Rhampsinitus flavobrunneus was described from a single specimen with the original collection locality given only as “ Afrique du Sud ”; Staręga speculated that it may have been collected near Johannesburg. Staręga did not explicitly compare R. flavobrunneus to R. nubicolus though he did assign juvenile specimens from Mariepskop to the latter species in the same paper. However, one of the features highlighted in the description of R. flavobrunneus was the ‘light yellow’ coloration of the holotype, whereas R. nubicolus was originally described as black. The specimens examined herein, though mostly dark, show a range of coloration from dark to pale. One male that had recently moulted before collection (as indicated by its lack of sclerotisation) was a pale grey dorsally with the anterior part of the carapace light yellow and the legs cream-coloured. As has been described for other Phalangioidea ( Shultz 2008), it seems likely that the cuticle darkens in coloration as it hardens with maturity. The use of colour patterns in distinguishing species of Phalangioidea should be treated with caution.

The genital morphology of R. nubicolus is very similar to that of R. transvaalicus , as illustrated by Schönhofer (2008), and the known distributions of these species are in close proximity. Major males of R. nubicolus may also resemble R. transvaalicus in the apparent presence of an enlarged ventrolateral denticle row on the first cheliceral segment ( Schönhofer 2008), though the degree of development and/or prominence of this feature may vary between individuals of both species. However, having examined specimens of both R. nubicolus and R. transvaalicus (see details of R. transvaalicus specimens in the Methods section above), I am disinclined to regard them as synonyms. Males of R. transvaalicus , even particularly large ones, usually have much shorter pedipalps than major males of R. nubicolus , with the pedipalpal femur much shorter than body length in R. transvaalicus vs close to or much longer than body length in R. nubicolus , and the pedipalps are never denticulate. The anterior margin of the carapace in R. nubicolus bears a distinct median denticle whereas this is absent in R. transvaalicus . The most striking difference between the two species, however, is the presence in R. transvaalicus of an array of enlarged, distally-projecting denticles at the end of the proventral denticle row on femur I. In contrast, the denticles in the corresponding position in R. nubicolus are a similar size to or smaller than those on the remainder of the leg. This enlarged denticle array remains distinct even in minor males of R. transvaalicus .

A similar arrangement of denticles on femur I was described by Lawrence (1931) for his species Rhampsinitus flavidus and R. unicolor , which were distinguished from each other by coloration and slight differences in biometric proportions. Both had type localities in the near vicinity of Leydsdorp in Limpopo province, and it seems likely that they represent the same species. Two specimens from the neighbourhood of Tzaneen are identified herein as R. unicolor (see Methods section for details) but are also similar to minor males of R. transvaalicus . Apart from being slightly more bulbous at the base of the shaft, the penis of these specimens is identical in size and appearance to that of the minor male of R. transvaalicus . There are some minor differences in external armature: the chelicera of R. unicolor has the second segment largely unarmed laterally and on the anterior face distally (vs more evenly denticulate in R. transvaalicus ), and the denticle rows across the opisthosomal tergites are more irregular in R. unicolor (though they are also somewhat irregular in the smallest specimens of R. transvaalicus from the Hanglip Forest). More notably, the R. unicolor specimens have relatively longer appendages: the pedipalpal femur is more than half the body length vs somewhat less than half in R. transvaalicus , and they have proportionally longer legs than similarly sized individuals of R. transvaalicus . The relative status of R. transvaalicus , R. flavidus and R. unicolor remains uncertain pending the examination of further specimens. Also requiring re-examination is R. granarius Roewer 1916 , described by Roewer (1916) from a single male from Johannesburg, whose distinctiveness from R. flavidus was questioned by Staręga (2009).

Figures

FIGURE 4. Rhampsinitus nubicolus Lawrence 1963; A, C, E – H: minor male, Misty Mountain Hotel; B, D: major male, Misty Mountain Hotel; G: female, Mariepskop. A: body, male, dorsal view; B: body, major male, lateral view; C: body, minor male, lateral view; D: right pedipalp, major male, lateral view; E: left chelicera, minor male, lateral view; F: penis, left lateral view; G: glans, left lateral view; H: penis, dorsal view; I: female.

FIGURE 5. A: Rhampsinitus transvaalicus Lawrence 1931, major male, leg I, distal end of femur and patella, prolateral view. B: R. nubicolus, major male, leg I, distal end of femur and patella, prolateral view. C – F: R. unicolor, male; C: dorsal view; D: lateral view: E, penis, dorsal view; F: penis, right lateral view.