Howard E. Evans.
Studies on Neotropical Pompilidae (Hymenoptera) II. Genus Aridestus Banks.
Psyche 73(2):116-122, 1966.

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STUDIES ON NEOTROPICAL POMPILIDAE
( HYMENOPTERA)
11. GENUS ARIDESTUS BANKS*
BY HOWARD E. EVANS
Museum of Comparative Zoology
Banks (1947, Bull. Mus. Comp. Zool., 99: 432) based the genus dridestus on a single female from Paraguay. This specimen was identified as "bergi Brethes" although in fact bergi is a Holmberg species, described in 1881 from a single female from the province of Buenos Aires, Argentina. I have before me fifteen females and six males which I consider to be congeneric with bergi, and it seems ap- propriate to present a fuller description of the genus Aridestus on the basis of this additional material.
In his generic description, Banks emphasized the transverse striae on the propodeurn. As a matter of fact these striae are absent in the male bergi and in both sexes of a Chilean species which is exceed- ingly similar to bergi in all other respects, including the male termi- nalia. I therefore find it desirable to define Aridest'us somewhat differently than did Banks. I consider Evagetes, Aridestus, and the African genus A'sfhenoctenidia Pate (=Asthenoctenus Arnold) to form a closely knit generic conlplex characterized by the thickened and slightly flattened antennae, by the reduced pulvillar pad and comb, by having the clypeus no wider than the lower front, and by several other common features. Evagetes is known to be a clepto- parasite of other Pompilini, and it seems to me very likely that the other two genera behave similarly.
The known species of Aridestus are black with the abdomen mostly or entirely red, and they are especially similar to those species of Evagetes Raving the abdomen partly rufous and the pronotum sub- angulate behind (e.g. crassicornis Shuckard) . The species of Aridestus differ in having the clypeus, front, and vertex narrow, the middle interocular distance not exceeding .58 times the transfacial distance in either sex, the clypeus not more than 2.5 times as wide as high in the female, 2.2 times as wide as high in the male. The pronotum is also short medially and in the female somewhat swollen antero- laterally, there is an unusually distinct median groove on the front, and the marginal cell is far removed from the wing-tip (at least *Published with the aid of a grant from the Museum of Comparative Zoology.
Manuscript received by the editor May 15, 1966,



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19661 Evans -- Neotropical Pompllidae 117 by 1.6 times its own length). From Asthenoctenidia, Aridestus differs in having a much shorter and more angulate pronotum as well as a complete postnotum which is at least nearly half the length of the r 7
metanotum.
I he male terminalia of the three genera show only minor differences.
As noted above, the citation of the type species of Aridestus should be corrected to read : Pompilus bergi Holmberg, 1881 (monobasic). The following is a redescription of the genus. Small wasps, 5-12 mm in length; known species black with ab- domen rufous except often fuscous at extreme base and apex (apical fourth sometimes fuscous in males) ; males usually with an inter- ~upted pale yellow band along the posterior margin of the pronotum and always with the apical abdominal tergite in large part pale yellow or whitish. Mandibles with a single tooth on the inner mar- gin; clypeus truncate, its width equal to or slightly less than the lower interocular distance; front narrow, middle interocular distance not exceeding .58 times transfacial distance; front with a median linear impression from the antennal bases to the anterior ocellus; vertex passing nearly straight across between tops of eyes. Antennae short and in the female slightly incrassate, the flagellar segments somewhat flattened on the outer surface; third antennal segment in the female 2.5-3.5 ti~nes as long as thick, .50-.65 times upper inter- ocular distance; third antennal segment in male shorter than fourth segment, 1.4-1.9 times as long as thick; apical antennal segment of male obliquely truncate at tip. Pronotum along midline very much shorter than mesoscuturn, in the female somewhat bulging antero- laterally ; posterior margin broadly subangulate or subarcuate ; post- Figs. 1 and 2. Male genitalia of species of Aridatus, ventral aspect. Fig. 1. A. bergi (Holmberg). Fig. 2. A. jaffueli (Herbst).



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118 Psyche [June
notum a complete transverse band at least nearly half as long as the metanotum ; propodeum relatively short and strongly convex, with the median line impressed basally, the posterior slope with or without transverse rugae. Middle and hind tibiae with sparse but fairly strong spines above; front tibiae not at all spined above; female with a strong tarsal comb, the spines very long and slender, the apical basitarsal spine longer than the second segment; apical tarsal seg- ments at least weakly spined beneath in the females; claws slender, dentate except inner claws of front tarsi of males strongly curved, somewhat bifid, this tarsal segment weakly lobed on the inner margin; pulvillar pad very small, giving rise to 2-6 minute setae. Wing venation essentially as in Evaqetes (see Evans, 1950, Trans. Amer. Ent. Soc., 75 : 162, Figs. 12, 13) ; marginal cell I .6-2.1 times its own length from the wing tip; second and third submarginal cells small, both narrowed above. Male subgenital plate simple, its sides tapering to a broadly rounded or subtruncate apex; male genitalia with the basal hooklets single, the aedoeagus simple, bearing a few minute apical setae ; parameres fairly broad, strongly setose (Figs. I, 2)
Key to species
Females
I.
Propodeum without transverse rugae; inner orbits more strongly convergent at the top, upper interocular distance 34-.go times lower interocular (Chile, Patagonia) .... 3. jaffueli (Herbst) Propodeum with fairly strong transver,se rugae; upper inter- .................... ocular distance .g3-1.00 times lower interocular 2
2. Transverse rugae reaching the extreme side margins of the propodeum ; pubescence of head and thorax wholly dark ; scape, head, and front coxae with rather strong dark setae; length 12 mm (Peru)
............................................ 2. porteri n. sp. Transverse rugae stopping well short of side margins of pro- podeum; pubescence silvery at least on the clypeus, parts of the front, coxae, thoracic pleura, and propodeum, often ex- tensively silvery; front coxae without dark setae, scape with at most a few setae; length 5.7-9.0 mm (northern Argentina, Paraguay, southern Brazil) .................... I. bergi (Holmberg) Males
Abdomen more or less fuscous beyond the fourth segment; clypeus and scape with only a few setae; inner orbits divergent above, upper interocular distance
I. I 3-1.20 times lower interocular ;




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19661 Evans - Neotropical Pompilidae 119 parapenial lobes shorter than aedoeagus and digiti (Fig. I ) ..~. .................................................................. I. bergi (Holmberg) Abdomen almost wholly rufous, the subgenital plate contrastingly black; clypeus and scape with rather dense, black setae; inner orbits subparallel, upper interocular distance I .OO-I -05 times lower interocular; parapenial lobes large, slightly exceeding aedoeagus and digiti (Fig. 2) .................. 2. jaffueli (Herbst) I. Aridestus bergi ( Holmberg)
Pom$ilus bergii Holmberg, 1881, Anales Soc. Cient. Argentina, 12: 142. [Type: 52, ARGENTINA: Prov. Buenos Aires (C. Berg) (Mus. Arg. Cienc.
Nat.) 1.
Aridestvs bergi Banks, 1947, Bull. Mus. Comp. 2001. Harvard, 99: 432. Female. -Length 5.7-9.0 mm; fore wing 5.0-7.0 mm. Head and thorax black, the pubescence silvery at least on the clypeus, lower front, anterior and posterior parts of the pronotum, parts of the pleura and leg-bases, and posterior slope of the propodeum, often almost wholly silvery-sericeous, the band along the pronotal margin especially heavy; abdomen rufous except black at extreme base, apex sometimes weakly infuscated, wholly covered with fine, pale pubes- cence; wings subhyaline or lightly infuscated, with a broad darker band along the outer margin of the fore wing. Temples and pro- pleura with some erect hairs, body otherwise barely hairy except for dark hairs on the clypeus, front, vertex, and scape in occasional specimens. Clypeus 2.1-2.4 times as wide as high, truncate or slightly concave apically. Front narrow, middle interocular distance .52-.58 times transf acial distance ; upper interocular distance .95- I .OO times lower interocular; POL subequal to or slightly exceeding OOL. Third antenna1 segment 2.8-3.5 times as long as thick, equal to .50- .63 times upper interocular distance. Posterior slope of propodeum with transverse rugae, but the rugae not nearly reaching the extreme lateral margins. Front basitarsus with three comb-spines, the basal one usually shorter than the others. Third submarginal cell tri- angular or subtriangular.
Male. - Length 5.5-6.0 mm ; fore wing 4.8-5. I mm. Head and thorax black except posterior margin of pronotum with a pale band; abdomen rufous except extreme base black, fifth and sixth segments fuscous, apical tergite whitish; body very extensively clothed with silvery pubescence, the pubescence dark on the vertex, most of the mesoscutum and scutellar disc, and base of the fifth abdominal seg- ment; wings hyaline, with a broad brownish band along the outer margin of the fore wing. Temples and propleura with abundant pale hairs; scape, front, and vertex with short, dark setae. Clypeus



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120 Psyche [June
2.0 times as wide as high. Front narrow, middle interocular distance .55-.57 times transfacial distance ; middle interocular distance I .25- I .30 times lower interocular distance, upper interocular distance I. 13- 1.20 times lower. P0L:OOL about as 6:s. Third antennal seg- ment 1.5-1.9 times as long as thick, sometimes barely shorter than fourth segment. Subgenital plate roundly elevated medially; geni- talia as shown in Fig. I.
Distribution. - Northern Argentina, Paraguay, southern Brazil. Specimens examined. - 10 ?$, 4 cf d. ARGENTINA: I 2, Volcan, Jujuy, 2500 meters, 4 Dec. 1964 (C. C. Porter) [MCZ], PARA- GUAY: I 9, Villa Rica (I?. Schade) [MCZ]. BRAZIL : 8 $$, 4 d' & Nova Teutonia, Santa Catarina, Oct. - March (F. Plaumann) [MCZ, Coll. G. R. Ferguson].
Remarks. - The specimen from Jujuy is from a considerably higher altitude from the others, and is the only female studied which has black hairs on the scape and on the front and vertex; this speci- men also has the pale pubescence somewhat reduced, that on the front tending to form streaks along the sides and along the median sulcus, as in the Chilean species jaff'ueli. With respect to pubescence and pilosity, this specimen seems to occupy an intermediate position among the three species (as it does geographically), but in all struc- tural characters it agrees very well with specimens of bergi from lower and more easterly localities.
2. Aridestus porteri new species
Holotype. - 9, PERU : Cuzco, 3800 meters, Sept. 20 - Oct. 2, 1964 (C. C. Porter) [MCZ, No. 31,1821.
Description of female type. -Length 12 mm; fore wing 9 mm. Head and thorax black, rendered somewhat bluish by the wholly dark pubescence; abdomen rufous, only the extreme base of the first segment and extreme tip of the apical segment infuscated; wings fuscous, violaceous, fore wing distinctly darker in a broad band along the outer margin. Head rather densely dark-haired, including the scape; propleura hairy; pronotum, front coxae, and lower part of mesopleura (in front of middle coxae) with a few dark setae. Clypeus 2.2 times as wide as high. Front of moderate breadth, middle in- terocular distance .58 times transfacial distance; upper interocular distance -93 times lower interocular; POL and OOL subequal. -
third antennal segment 3.0 times as long as thick, equal to .56 times upper interocular distance. Transverse rugae of propodeum strong, the more posterior ones extending all the way to the ridge separating the propodeum from the metapleura. Fore basitarsus with



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19661 Evans - Neotropical Pompilidae 12 I three long comb-spines and a shorter one basad of these. Marginal cell removed from wing tip by a distance equal to 1.85 time,s the length of the marginal cell; third submarginal cell narrowed by three-fourths above, but not triangular. Renzarks. -This large and well characterized species is known only from the type. It was collected at the same time and place as a long series of Ponzpilus (Arachnospila.) dichromorphus (Rohwer) , to which it bears a stsong superficial resemblance. 3. Ar-idextzis jafueli ( Hei-bst) new combination Pom$ilus jaffueli Herbst! 1923, Revista Chilena Hist. Nat., 25: 150. [Type: $?,CHILE: Marga Marga, Prov. Valparaiso, Jan. 15) 1919 (F. Jaffuel) (MCZ, No. 17,184)].
Female. - Length 7-9 mm; fore wing 6-7 mm. Head and thorax black, the dorsum rendered somewhat bluish by the pubescence, with an extensive pattern of silvery pubescence as follows: sides of clypeus, a streak along the inner orbits afid also up the median frontal sulcus, temples, 211 coxae, propleura) pronotum anteriorly and along the posterior margin? posterior margin of mesoscutum) sides of scutellum) rnetanotum, and most of the propodeum and pleura; abdomen rufous, extreme tip sometimes infuscated, clothed with fine, pale pubescence; wings lightly infuscated, with a broad darker band along the outer margin of the fore wing. Front with short, dark hairs; clypeus and scape with a few hairs; temples and propleura clothed with pale hairs. Clypeus 2.3-2.5 times as wide as high, truncate apically. Front narrow, middle interocular distance .5~--55 times transfacial distance; upper interoc~dar distance -84--90 times lower interocular, the inner orbits thus somewhat more distinctly convergent above than in bergi. POL subequal to or slightly exceeding OOL. Third an-
tenna] segment 2.5-3.0 times as long as thick, equal to -55--64 times upper interocular distance. Median impression of propodeum nearly complete, the propodeum completely without transverse rugae. Front basitarsus with three strong comb-spines, sometimes with a weak fourth spine basad of these. Third submarginal cell subtriangular. ,Male, -Length 5-0-7.5 mm; fore wing 4.2-6.0 mm. Coloration of body, wings, and p~lbescence much as in the female except for the usual pale yellow ~narkings on the pronotum and tip of the abdomen; abdomen almgst wholly rufous and covered with a fine, pale p~bescence; subgenital plate black; scape with some dark hairs beneath, clypeus, front, and vertex also more conspicuously hairy than in the female. Clypeu? 2.1-2.2 times as wide as high. Front nar- row) mid(1le interocular distance -56 times transfacial distance; mid- dle interocular distance I .I 5-1 -20 times lower interocular ; upper



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122 Psyche [June
interocular I -00-1 .os times lower. POL :OOL about as 4 :3. Third mtennal segment 1.4-1.6 times as long as thick. Subgenital plate with a strong median keel; genitalia differing from those of bergi only in having more heavily setose parameres, a more deeply cleft zedoeagus) and slightly longer and broader parapenial lobes (Fig. 2). Distribution. - Central Chile, Patagonia. Sfiecinzeus examined.-4 99, 2 8 d. CHILE: I 9) I d) Marga Marga, Prove Valparaiso, Jan. 15) 1919 (F. Jaffuel) [type and al- lotype) MCZ] ; I 9, I d, Valle 10s Piuquenes, Rio Blanco, Prov. Aconcagua, Feb. 7-12, 1964 (L. Pefia) [MCZ] ; I 9, Pi~hinahuel~ Prov. Arauco> 1400 meters, Jan. 3 I, 1954 (L. Pefia) [Coll. G. R. Ferguson]. ARGENTINA: I 9) Chubut, Patagonia (W. I?. H. Rosen- berg) [USNM] .
Rernarhs. -The closz similarity of the male genitalia of jafueli and bergi indicates conchsively that the presence or absence of rugae on the female propodeun~ should not be regarded as a generic char- acter. The description and drawing of the genitalia of jaffueli were made from the specimen from Valle 10s Piuquenes. The genitalia of the allotype we-re extracted some years ago by R. R. Dreisbach, but the slide which he prepared contains onli a broken fragment of the subgenital plate, the genitalia presumably having been lost.



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