i f f
130 O i i D E R — I I Y A i E X O r T E R A .
pes autieus) ; ala} auticie cellula una marginali, 4 snbmarginalibus; prima magna aecepit veuam primam reeurrontem,
secuuda parva trigona, tortia parva quadrata aceepit venam secundam rccnrrentem ; cellulis 3 discoidalibus
; alxlomen thorace jiaullo majus, dcpressum, subspatulatum ; segmento tertio ventrali in tuberculum
medium conieum elevato, quarto inciso.
S O M A D I N A SMITHII.
(Westw. IViuis. Ent. Soc. loc. cit.)
P l a t e XXIV, FIG. 7.
Lutea, fusco varia ; capite maculis 4 parvis inter et pone oeulos ; thorace linea media ad post-scutellum
oxtcusa, maculisque dnabus oblougis mesotlioraeis, fuscis ; margine postico segmentornm abdominalium albido ;
alis concoloribusj stigmate venisque castaneis.
Long. corp. lin. 5 ; expans. alar, antic, lin. 10|.
H a b i t a t ; Amazonia (Bates). In Jilus. Smith.
GESUS—KHOPALOSOMA.
(Cresson, Free. Eut. Soc. Pliiladelph. vol. iv. 1865, p. 58.)
Caput mediocre, thoracis latitudine ; oculi ovales, margine interno iucism-a semicircukri (fig. 9 a) ; ocelli
m a g n i ; mandibulffi parviE, o-dentata; (tig. 9 i) ; antennaj ? graciles, filiformes, alis longiores, maris 13-, freminas
:2-articulata?, non geniculatfe, articulo Imo parvo (Hg. 9 e) ; palpi valde elongati, 6-4-articulati (fig. 9 c, maxilla) ;
labmm, ut videtur, 3-lobatum (fig. 9f/). Thorax elongato-ovatus, collare brevi, lateraliter ad tegulas extenso, in
medio subtus profunile impresso (fig. 9 / ) ; petiolus abdominis thorace longior ; abdomen elongato-ovatum (fig.
9 mavis) ; pedes longi, graciles, hand spinoso-denticulati ; calcaribus tibiarnm valde elongatis (fig. 9 ff) ; tarsis
omnibus elongatis, simplieibus iu maribus, membranaceo-dilatatis in fa^minis (fig. 9/ i ) ; ungnibns dente medio
subtus armatis (figs. 9 i, 9 ¿•) ; puh-illoqne magno reeurvo instructis ; alie mediocres, antica; baud longitudinaliter
jilicatas, cellula una marginali, o snbmarginalibus, prima et sccnnda Eeqnalibus, secnnda aecepit venam primam
reeurrentem valde obliquam iu medio marginis postici ; secunda reonrrente, valde indistincta, cellnlam tert
i am diseoidalem chiudente, transversa, et apicem cellulse secundie attingente; alie posticas ad apicem venie
pobrachialis incisas.
Syn. : Sibyllina. Westw. Trans. Ent. Soc. Lend. 1868, part iv. December, p. 329.
This curious genus was considered (doubtingly) by the late ilr. Haliday (one of the most profound
Hymenopterologists) as one of the Sphegida;, with smooth legs, near Pelopajus, as appears by a note attached to
a specimen of the type in the Collection of the British Museum'.
On exhibiting a specimen of this insect at a meet ing of the Entomological Society, I expressed an opinion
of i t s relations embodied in the Ibllowing passage, subsequently pubhshed in the Transactions of the Society :—
' Genus novum Aculeatornm, quoad affinitates animum exerucians, sed ad familiam Vespidarum ut mihi videtur
magis approximans. Corpus elongatum, Belonogastri (^"espidarum) vel Pelopa;i (Sphegidarum) habitu, etiam
Formicarum nonnullarum antennis elongatis, non dissimile.'
Jilf. F. Smith, on the same occasion, also considered that ' i t had more characters in accordance with those
of the ants than with any other family.' (Proc. Ent . Soc. Nov. IG, 1868.)
Mr, Cresson, who first described this genus, placed it undoubtingly amongst the multitudinous genera of
lehncumonida; (which caused me to overlook it), remarking, ' I am at present unable to define the true position
of thi s remarkable genus. It seems to form a connecting link between the lehneumones genuini and the Adsciti j
from the former it differs by the paucity of the antennal joints, and from the latter, by the anterior wings
having a faint indication of a second recurrent nervure. Its structure jdaces it, beyond doubt, in the family
Ichneumonidie, whilst its general appearance, together with the arrangement of the wing-veins, seems to place it
among the Adsciti, where I \vill allow it to remain, for the present.'
Subsequently, jNIr. Smith (without being aware that the insect had been thus commented upon by
Mr. Cresson), in a paper communicated to the Entomological Society on the 4th Jan. 1869 (Trans. 1868, Proc.
p. li.) discussed the affinities of this genus at length with great acumen, contending, ' 1 st, That all wasps have
' ' Antennas frem. not geniculate; hind wings incised at end of the pobracliial vein; fore wings with a third discal
areole
See also form of thorax. I think a Sphegid, with smooth legs, near Pelopaius.' (Haliday MS. iu Brit, llus.)
F i U i i L T — E V A N I I D . E . 131
the^ wings folded, whilst they are flat in Rhopalosoma. 2nd, Rhopalosoma lurs only tivo .submarginal cells,
«•hilst every known wasp has either three or four. 3rd, livery true wasp has tliree discoidal cells'in the fore
wings, whilst Rhopalosoma has only one. 4th, The ]irothorax [collar] in all Vespidaj extends l)ack\vards to the
teguhc, which is not the case in Rhopalosoma. ,5th, Liuiate eyes (which Rliopalosoma possesses) are found iu
Mutilla, Scolia, Sapyga, Pemphrcdon, and Philauthus amongst the Aculcata, and in tlie lelmeumonideous
genera Pimpla, Campoplex, Anomalon, Ophion, and some others. 6t.h, The tarsal ungues (tootlied in Rliojjalosoma)
are simple in the social Vespida;, although dentate in the solitary wasps,' On the other hand, Mr. Smith
regarded the insect as belonging to the lehneumonides. ' 7th, Because, amongst the minute [Adscitous] groups,
species exist having only 12-jointed antenna; (Ephidrus), and others having 13-jointed antenna; (Trioxys),'
8th, Mr, Smith states ' that m Rhopalosoma a distnict second joint in the trochanters is quite as visible as in
the lehneumonideons genns jMetopius. 9th, The antenna; of every known species of wasp are geniculate, ^vhicli
is not the ease in Rhopalosoma. 10th, The prothorax of Rhopalosoma is of the same structure as in Ophion
and Anomalon. lUh, The ocelli are large and prominent in Rhopalosoma, as in the two last-named genera; in
t h e Vcspidie they are much smaller, and usually more sunken than prominent. 12th, The broadly ddated tarsi
in Rhopalosoma do not occur in Vespida;, but are peculiarly characteristic of Anomalon. 13th, The basal segment
of the abdomen of Rhopalosoma is narrowed into a petiole, as iu Ophion and Anomalon. 14th, Tlie sting
of Rhopalosoma agrees with that of Ophion and Anomalon, as well as Belonogaster and Vespa.'
Although thus pointing out the relationship of the genus with Ophion and Anomalon, Jlr, Smitli adnritted
its want of ' s t rong aflinity with any other known insect,'
To these objections I have to reply as follows :—
1. Some of the most aberrant wasp genera, and the remainder of the Aculeata, Iiave flat wings,
2. Rhopalosoma has three submarginal cells. In all the genuine Ichneumons, the first submarginal and the
anterior discoidal cells are thrown together. Even in those Adsciti whicli have three" d i s t inct submargmal
cells, the first (and only) recurrent vein enters the fir-st submarginal cell, and not the second, as
in Rhopalosoma.
3. Rhopalosoma has three discoidal cells, the lower outer one having its ext remi t y partially closed by a transverse
nearly obsolete vein,
4. The collar of Rhopalosoma extends back laterally to the tegula?, although not seen dorsally at the sides of the
thorax.
5. The eyes of Rhopalosoma are not lunate, but oval, wi t h a small emargination in the middle of the inner margin.
6. The ungues in Rhopalosoma are furnished beneath with two obtuse spines,
7. No species of Adscitous Ichneumon, nor indeed any other terebrant Hymenopterous insect, is known
possessing 13-joiuted antenna; in the males and 12-joinled in the females. This is one of the leading
characters of the Aculeata. ^
8. I cannot discover a second joint in the trochanters of Rhopalosoma. Its existence is one of the leading
characters of the terebrant Ifymenoptera. In certain positions, a faint appearance of an articulation
near the base of the femora may be observed. In the Ichneumons the two joints of the trochanters
are distinct, and nearly equal in size in many species.
9. The long, straight, filiform structure of the antenna; of Rhopalosoma is unquestionably a strong character
against its belonging to the Vcspida;.
10. The front of the thorax of Rhopalosoma is similarly formed to that of Ophion.
11. The ocelli of Rhopalosoma agree with those of Ophion,
12. I know no lelmeumonideous nor indeed any other Hymenopterous insect with feet like those of the female
Rhopalosoma, whereas they are simple in the male.
13. The pedunculated basal segment of the abdomen of Rhopalosoma occurs in many groups of Aculeata, as well
as in many of the Terebrantia.
14. The sting of Rhopalosoma is a genuine aouleus, with a broad sheath.
15. Tlie lobed base of the hind wing, and the 6-jointed maxillary palpi, which latter character occurs in no
genuine Ichneumon, must not lie overlooked in determining the relations of the genus.
From the preceding discussion it will doubtless be considered that, whilst in several important respects the
insect before us agrees with some of the Ichneumonida>, it is, in others equally important, allied to the Aculeata.
forming liy itself a most exceptional and isolated section.
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