A contribution to the sawfly fauna o f the Brandberg Massif in Namibia ( Hymenoptera : Symphyta : Argidae , Tenthredinidae )

Im Rahmen von zwei entomologischen Expeditionen zum Brandberg Massif im westlichen Namibia in den Jahren 2001 und 2002 wurden insgesamt 29 Pflanzenwespen gesammelt. Dieses Material enthalt drei Arten, von denen zwei, Arge meyi n. sp. und Pampsilota brandbergensis n. sp., als neu beschrieben werden. Auserdem wurde Xenapates damaraensis Koch, 1995 erstmalig im Brandberggebiet gefunden. Eine aktualisierte Verbreitungskarte von X. damaraensis wird vorgelegt.StichworterNew species, Symphyta, Argidae, Arge Schrank 1802, Pampsilota Konow 1899, Tenthredinidae, Xenapates Kirby 1882, Namibia, Nama-Karoo, Brandberg Massif.Nomenklatorische Handlungenmeyi Koch, 2006 (Arge), spec. n.brandbergensis Koch, 2006 (Pampsilota), spec. n.


Introduction
In the Afrotropical region the sawfly fauna is very poor both in number of species and individuals in comparison to other biogeographical regions, except for Australia.The taxonomy of Afrotropical sawflies is partly outdated, incomplete and in some cases in correct.
In the middle of the last century, the taxonomic contributions of P a s t e e l s (1949,1953) were very important for the knowledge of the distribution of Afrotropical sawflies.He concentrated on the fauna of the Belgian Congo and the countries adjacent to its eastern border (Rwanda, Uganda).Only the revision of the Athaliini by B e n s o n (1962) con tains all known Afrotropical A thalia species, but it is currently also necessary to revise this genus.
Little or nothing is known about host plants, larval stages and phenology of the species in this region ( C h e v i n 1985, K o c h 2003).Among other reasons this poor knowledge of Afrotropical sawflies can be explained by the previous lack of collecting specifically targeting sawflies in Africa.In the past 12 years the Entomological Africa Expeditions of the Museum of Natural History, Berlin, through southern Africa, especially Namibia, have been very valuable in increasing our knowledge of the Namibian sawflies.Additionally, the material of other collections, especially that of the State Museum of Namibia, was investigated.At present 16 species of two families, Tenthredinidae and Argidae, are reported for the Namibian sawfly fauna.Most of these species have been sampled in more humid habi tats of the northern parts of Namibia ( K o c h 2 0 0 0 ) , especially in the Caprivi strip, along the stream banks of Okavango and Kunene as well as around permanent and temporary still waters.In view of this contrasting previous experience records of Symphyta in the semi-desert ar eas including the Brandberg Massif were hardly expected.The material of the Brandberg expeditions is very important for the knowledge of the diversity, distribution and eco logical adaptability (tolerance) of Afrotropical Symphyta.

Sampling methods
The present sudy is based on material amassed by W. M e y (M N H U ), E. M a r a i s and A. H. K i r k -S p r i g g s (both N M N W ) during field trips to the Brandberg area in 2001 and 2002.A total of 29 specimens, representing three species, were collected by the use of Malaise traps and sweep-net.Additional material was provided by CASC.

Characteristics of study areas
The Brandberg M assif is an isolated mountain range in western Namibia on the eastern edge of the Namib desert.Female.-Head yellow; postocellar and interocellar area including margin of front ocellus and antenna black, narrow base of scape yellow, mandible apically dark brown.Thorax yellow; mesoscutum with three large black spots, parapsis and mesosternum black.Legs yellow; dorsal surface of hind coxa and narrow apex of hind femur, hind tibia apically, mid and hind tarsi blackish.W ings hyaline; fore wing with a slight smoky substigmal spot, intercostal area slightly infuscated, costa entirely yellow, subcosta brown, stigma and veins blackish.Abdomen yellow with blackish narrow anterior margin on terguny, terga5 each with small blackish medial spot.Head slightly enlarged behind eyes.Antenna 1.3x as long as maximum head width; 3rd segment slightly enlarged toward apex, triangular in cross section, inside with moder ately compressed longitudinal carina.POL : OOL = 1.0 ; 0.9 (HT).M S: IA = 1.0 : 4.8 (HT).Eyes slightly converging below, lower interocular distance 1.3x eye length; clypeus triangular excised medially about 1/3 of its median length, supraclypeal area rounded Host plant: Two females have been sampled with Malaise-traps.The other specimens (5 males, 3 fe males) were collected selectively using a sweep-net on C om m iphora saxícola.This bush or small tree is endemic to the southwestern Africa semi-desert vegetation type, occurring on stony hills and rocky mountain slopes in the fringes of Namib.Therefore, if A. m eyi is monophagous on this plant, it seems likely that the sawfly is also endemic to this region.

Remarks:
The colour pattern is variable in this species.In females, the black markings on the abdo men may be extended, with a small spot on tergum5, and sometimes the ventral surface of the hind coxa is blackish.In males, the black on the abdomen is either reduced to a black tergunij and median spots on terga5_8 or extended to broad markings on tergaj 2 4 and median spots on terga3g.The POL : OOL ratio varies 1.0 : 0.8-0.9(females); the M S : IA ratio varies from 1.0 : 4.5-4.9(females) and 4.3-5.0(males).According to P a s t e e l s (1953) the new species is similar to A rge a escu la pii F o r s i u s , 1925, but A. a escu la pii differs mostly by the bicoloured, sharply contrasted fore wings with flavescent hyaline basal and blackish infuscated apical halves and the entirely black mesonotum including the mesoscutellar appendage.Furthermore, black is the apical half of the postocellar area, the apical third of mid and hind femora, and the apices of the mid and hind tibiae are black.Additionally, in A. aescu lapii the inside of the sheath is covered with bristle-like hairs apically and longer hairs in the basal half (Fig. lg ).

Etymology:
This species is named after m y colleague Dr. W . M e y .Wings subhyaline; fore wing with slightly infúscate substigmal spot, costa and stigma light brown, subcosta and veins brown.Abdomen black; terga3 yellow with medio-apical blackish spot on tergum5, terga2 g yellow laterally, tergay with slight metallic lustre, sterna3 g yellow with medio-apical blackish marking, subgenital plate with yellow apical half.

Remarks:
Between holotype and paratype the variability in colour pattern is scarcely noticeable.The tergum5 may be entirely yellow and the pronotum m ay have a small ventro-lateral blackish spot.POL : OOL = 1.0 : 0.9 (PT).M S : IA = 1.0 : 3.0 (PT).Following the key of M a l a i s e ( 1 9 4 1 ) it is very difficult to find a suitable genus for this new species, because the subapical spine on the hind tibia is absent, the basal anal cell of the fore wing is present and the head is not distinctly small, not half as wide as the thorax (couplet 13).Neither is it possible to identify P. a fer K o n o w , 1899 (the type species of Pam psilota K o n o w ) using this key, because in dorsal view the head of P. a fer is likewise not distinctly smaller: actually much more than half as wide as the thorax.Based on M a l a i s e (1941) the new species seems to belong to C ibdela K o n o w , 1899.However, as far as it is known, C ibdela is an Oriental genus in which the distance be tween the origin of M and Rs+M is about as long as Sc.In the holotype of P. brand bergen sis M and Rs+M have the same origin (Fig. 2b), similar to Arge.In the paratype the distance between the origin of M and Rs+M is about as long as Sc (Fig. 2c); thus the venation is variable and therefore does not provide convincing generic level placement.
In the end, the new species is classified as a P am psilota species, despite its relatively small size compared to P. a fer (length 14.0-15.0mm), because it is not possible to find signifi cant morphological differences which would warrant placing these species in separate genera.However, a revision of the genus P am psilota might require a new placement of P. brandbergensis.

Etymology:
This species is named after the collection locality.This species was described from Kaross, near Etosha Pan (Namibia) collected in 1925.
Since then it was reported from different places in the Kaokoland ( K o c h 2000) and south to W indhoek (1 9 : Aris, 25 km S W indhoek, 5.II.1990,W. J. P u l a w s k i ) (CASC), (Fig. 3).As far as it is known, this species is endemic to the Nama-Karoo and Tree-and-Shrub Savannah Biomes of southwestern Africa.
T h u n b e r g (Ebenaceae), C yphostem m a cu rrori (J.D. H o o k e r ) D e s c o i n g s (Vitaceae) and Rhus spec.(Anacardiaceae).Mason Shelter (1.800 m): A more or less flat plain, dissected by some small river beds and fringed by rocky hills with huge boulders and rock slabs.This an upper drainage area of Nawuarib River, containing on the plain some single trees of A cacia hereroensis, F icus sycom orus L i n n e (Moraceae) and Ozoroa crassin ervia ( E n g l e r ) R. & A. F e r n a n d e s (Anacardiaceae), abundant small trees of C om m iphora saxicola E n g l e r (Burseraceae) and scattered individuals of S terculia q u inqu eloba ( G a r c k e ) K. S c h u m a c h e r (Sterculiaceae), G alenia a frica n a L i n n e (Aizoaceae), E riocephalus d in teri S c h e l l e n b e r g (Asteraceae) and C yphostem m a cu rrori at the south ern margin of the plain.In addition low shrubs of Salsola sp.(Chenopodiaceae) are evenly dispersed throughout.ArgidaeA rge m e y i n. sp.
Fig la-g: Arge m eyi n. sp.-a lan cet lateral aspect).-b serrulae 10-11.-c saw sh e a th (dorsal aspect).-d p enis valve (left, lateral aspect).-e penis valve (rig h t, v en tral aspect).-f h a rp e a n d p arap en is (rig h t, v e n tra l aspect); Arge aesculapii F o r s i u s .-g saw sh e ath (dorsal aspect).

Abbreviations used in the text:
The highest peak is Konigstein, at 2.573 m above sea level.
to interantennal carinae, interantennal carinae not sharply ridged, slightly converging downward, ending about half distance to clypeus.Vertex and gena shining, nearly impunctate, frons, clypeus and supraclypeal area w ith scattered, shallow punctures, shining.Hairs yellowish, about a half diameter of a lateral ocellus.Thorax very sparsely punc tured, shining.Hairs on median lobe of mesoscutum pale yellow, shorter than on head, lateral lobes w ith broad glabrous strip, only laterally sparsely haired.Abdomen shining, tergunij with transverse microsculpture.Sheath as in Fig.lc, with coarse, very short, blunt bristles.Lancet with about 19 serrulae, those at base roundly pointed at apices, serrulae at apex and centre large and flat (Fig.la), with 13-14 subbasal teeth (Fig.lb).Head black, frons, clypeus and labrum yellow, narrow base of scape yellow, m an dible yellow with apex dark brown, gena brownish yellow.Thorax black; pronotum yel low with black median mark, tegula yellow, mesoscutellum brownish yellow with black at base.Legs yellow; coxae, mid and hind trochanters black, narrow apex of hind femur, hind tibia apically, and hind tarsi blackish, middle tarsomeres of m id tarsus brownish.Costa of fore wing brown.Abdomen yellow; tergat 2 broadly black, tergumg with black median spot, tergaJ4 with narrow blackish transversal marks.
ale. -Head and antenna black; anterior margin of labrum brown, apical half of man dible brown becoming dark reddish apically.Thorax black; pronotum and tegula yel low.Legs black; anterior surface of fore tibia brownish yellow, posterior surface brown.