Neoperla Needham (1905)

Ogbogu, Sylvester S., 2006, First Report Of The Nymph Of Neoperla Needham, 1905 (Plecoptera: Perlidae) From Ile-Ife, Southwestern Nigeria, Illiesia 2 (4), pp. 27-30 : 27-29

Neoperla Needham (1905) ,

( Figs. 1-3 )

Neoperla Needham, 1905, p. 108 .

Material examined. The specimens (mature nymphs) examined were collected by Elo Okeze from a stream that cross Ede road at a distance of 1km below Opa reservoir in Obafemi Awolowo University, Ile-Ife, Osun State in southwestern Nigeria (2.12.2004, 007 ° 30.2’N, 004 ° 31.8’E; 141m). The stream is shaded, with gravel bottom and varying seasonal water current velocity. One specimen was stored in 70% ethanol and has been deposited in the Natural History Museum (NHM) at Obafemi Awolowo University, Ile Ife, Nigeria. To observe the morphological features of nymph, one specimen was whole-mounted on a slide in Canada balsam and viewed under the microscope. Further observations were made with the microscope on fresh specimens as well as those preserved in 70% ethanol. Diagnostic characters of larva. Neoperla nymphs are relatively distinctive at the generic level by virtue of their two close-set ocelli and the occipital spinule row which transverses over head forming an elevated ridge behind the ocelli. Species level identifications, at least at present, require adult specimens. Figure 1 shows the head and pronotal pattern and Figures 2-3 show the proventricular armature for an undetermined specimen. The latter character has been shown to have some potential for recognition of perlid nymphs by Stark & Gaufin (1976).

DISCUSSION

The genus Neoperla has been recorded from several countries in the Afrotropical region ( Hynes 1952, 1953, 1969; Tjonneland 1961; Zwick 1973 a, 1976a, b; Picker 1980) and the species N. spio is reported to be widespread ( Needham 1920; Picker 1980). In the checklist of Neoperla from South Africa ( Villet 2000), three species are recognized, two of which are unknown and recorded as Neoperla spp . 1 and 2. The difficulty in the identification of specimens down to species level may be linked to the problem arising from the possible existence of a species complex among the Afrotropical region Neoperla ( Hynes 1952; Picker 1980). The occurrence of species complexes appears to be a common phenomenon in the genus as has been observed in N. clymene ( Stark 1990; DeWalt et al. 2002) and Neoperla montivaga (Zwick 1983, 1986). Recently, Zwick (2003) suggested many morphospecies may be widespread across Africa, and noted that there are examples of differences in similar specimens from different regions. Arising from this, Zwick (2003) suggested two possibilities: 1) geographic variation between conspecifics and, 2) close relationship between different species of Neoperla . In line with Zwick’s (2003) suggestion it can be inferred that contrary to the belief that all African Neoperla belong to one extremely variable N. spio ( Hynes 1952) , there may be a number of species that are unknown. Moreover, known species may have wider geographical ranges in the Afrotropical region than are currently thought. This is possible given at least some American species of Neoperla are univoltine and can survive even in unusual habitats such as temporary streams ( Stewart et al. 1974). N. spio has been observed in open shores

of large lakes such as Lake Nyasa in addition to its occurrence in cool, forested streams elsewhere ( Hynes 1976). Further examination of nymphs and adults of Neoperla from Nigeria is needed to determine whether they are those of N. spio or some entirely different species.

Figures

Fig. 1. Neoperla sp. larva. Head and pronotum, dorsal view.

Figs. 2-3. Neoperla sp. larva. Proventriculus armature.