W. M. Wheeler.
The Ant Genus Rhopalomastix.
Psyche 36(2):95-101, 1929.

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The Ant Genus Rhopalornastix
THE ANT GENUS RHOPALOMASTIX1
The genus Rhopalomastix was established by Fore1 in 1900 for a very aberrant female Myrmicine ant (Rh. roth- neyi) taken by G. A. J. Rothney at Barrackpore, near Cal- cutta, India2. In 1911 he detected the worker and male of this species and also the female of a second species or sub- species (Rh. escherichi) among the ants collected by Prof. K. Escherich in Ceylons, and was therefore able to recognize the close relationship of the genus to Melissotarsus Emery, which now comprises four species, confined to the Ethiopian and Malagasy Regions, namely, M. beccarii Emery from Erythrea and Natal, erneryi Fore1 from southern Ethiopia, with a var. pilipes Santschi in East Africa, weissi Santschi from the Congo and insularis Santschi from Madagascar. In both genera, which together now constitute the tribe Melissotarsini, the antennae of the worker are very short, with much enlarged terminal joint, the frontal carinae are closely approximated and resemble those of certain Pon- erinae (Ponera), the thoracic dorsum is sutureless and the tibiae of the middle and hind legs are spurless. The wings of the male and female lack the discoidal cell, and have a long cubital and a closed and appendiculate radial cell. The anten- nae of the males are 12-jointed in both genera, but the worker of Melissotarsus has the antennae composed of only 6 joints, whereas there are 10 in Rhopalomastix. Melis- sotarsus is also peculiar in possessing conspicuously dilated basitarsal joints on all the legs. Emery4 believed that the worker of M. beccarii was distinctly dimorphic, or repre- Contributions from the Entomological Laboratory, Bussey Institution, Harvard University, No. 313.
Worel, A. Un nouveau genre et une nouvelle espece de Myrmicide. Ann. SOC. Ent. Belg. 44, 1900, p. 24-26.
SForel, A. Ameisen aus Ceylon. In K. Escherich's "Terrnitenleben auf Ceylon", 1911 pp. 215-228.
^Emery, C. Catalogo delle fonniche esistenti nelle collezioni del Museo Civico di Genova. Part I. Anal. Mus. Civ. Genova 9, 1877 p. 378-379, fig.



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96 Psyche [June
sented by a soldier phase (Fig 2) with anteriorly broad head and convex blunt-toothed mandibles and a worker phase proper with anteriorly narrower head and acute mandibles, but Arnold5, who examined a long series of this species, finds a complete gradation between the two forms. Several years ago Viehmeyer sent me eleven workers and two immature males of a Rhopalmoastix belonging to a series taken by H. Overbeck at Singapore. Viehmeyer6 had recorded them as belonging to Rh. rothneyi, but on compar- ing them with Forel's description I find that they differ in size and coloration and therefore probably represent a dis- tinct subspecies, which is here described : Rhopalomastix rothneyi Fore1 subsp. johorensis subsp. ROV.
Worker. Length 2 - 2. 6 mm.
Distinctly larger than the typical rothneyi, which meas- ures only 1.7 - 1.8 mm. Head scarcely longer than broad (1 1/6 longer than broad in rothn,eyi) and with somewhat smal- ler eyes (13 to 15 facets, instead of about 20). Head and thorax rich ferruginous red ; appendages, abdomen and sides and declivity of epinotum clear brownish yellow. I have recently received another series of specimens, comprising all three phases of a second subspecies of roth- neyi from Java, which may be described as : Rhopalomastix rothneyi subsp. javana subsp. nov. (Fig. 1)
Worker. Length 1.3-1.8 mm.
Averaging smaller than the typical form of the species. Head not longer than broad; thorax shorter, only 1 2/3 times as long as broad, with the epinotum distinctly nar- rower than the promesomotum. Median tooth of the anterior clypeal border very indistinct. Eyes smaller, consisting of only 12 to 14 facets. Sculpture finer than in the subsp. joho- rensis; color similar, but the head and thorax more yellowish ferruginous, the gaster clouded with brown apically. SArnold, G. A Monograph of the Formicidas of South Africa, Ann. South Afr. Mus. 1916 p.
188 nota.
Wiehmeyer, H. Ameisen von Singapore. Arch. Naturg. 81, (1919) 1916 p. 108-168, IS figs.




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19291 The Ant Genus Rhopalomastix 9 7
Fig. 1. Rhopalomastix rothneyi Fore1 subsp. javana subsp. nov. a, worker in profile; b, head of same, dorsal view; c, antenna of same; d, head and antenna of male; e, wings of same.
Fig. 2. Melissotarsus beccarii Emery. a, broad-headed worker, dorsal view; b, antenna of same; c, head of narrow-headed worker (After C. Emery) ; d, mandible of broad-headed worker; e, mandible of narrow-headed worker (After G. Arnold).




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Female (dealated) . Length 2.5-2.8 mm.
Antennae 10-jointed as in the worker. Deep castaneous brown ; pronotum, thoracic sutures, pedicel and appendages paler, more reddish brown. Sculpture as in the typical rothnepi, the anterior third of the head and the thoracic dorsum very finely longitudinally striated, the posterior portion of the head shining, sparsely and rather coarsely punctate, the gaster shining, with finer, piligerous punc- tures.
Male. Length 2-2.3 mm.
Black, with brown appendages. Wings clear and hyaline, with dark brown veins and pterostigma, the latter small and subelliptical. The costal vein is absent basal to the pterostig- ma and there is a distinct indication of a former division of the long cubital cell into two cells and pale indications of former prolongations of the cubitus and discoidal veins towards the tip of the wing. The hind wing is narrow and has only one distinct vein, the media.
Described from numerous workers, four females and three males taken at Bondowoso, Besoeki, Eastern Java and received from Dr. L. G. K. Kalshoven.
My female specimens of javana do not agree with Forel's description of the typical rothneyi in the number of anten- nal joints. In his generic diagnosis he gives the number as 11, which is also the number given by Emery in the "Genera Insectorum," but in my specimens the number is certainly 10. Probably Fore1 did not examine balsam mounts, without which it is impossible to determine the precise number of the very short and crowded median joints of the funiculus. That both worker and female of Rhopalomastix have the same number is also indicated by the conditions in Melis- sotarsus, both the female phases of which have 6-jointed antennae.
Apart from the complete absence of spurs on the middle and hind tibiae, the legs of Rhopalomastix also show pecul- iarities in the structure of the worker and female tarsi, which are by no means of the "common form" as stated by



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19291 The Ant Genus Rhopalomastix 99
Forel. To be sure, the basitarsi are not dilated as in Melis- sotarsus, but the second to fourth joints are unusual in being extremely short, obliquely prolonged on each side and over- lapping.
In regard to the palpal joints, I am unable to add any- thing to Forel's statement that in the worker the "labial palpi are two-jointed, the maxillary palpi not to be found." Perhaps the latter are present but greatly reduced. The peculiarities of the wing-venation are inadequately described by Forel. As will be seen from Fig. Ie, the fore wing is peculiar in completely lacking the costal vein basal to the pterostigma, in the shape of the pterostigma, and the length of the cubital cell which exhibits traces of a division into two. Fore1 compares the venation with that of Solenop- sis, but it is clearly more like that of Myrmecina, especially in the structure of the radical cell. According to Arnold, the apterostigma is almost obsolete in Melissotarsus. Both the genera of Melissotarsini have essentially the same nesting habits, as shown by the following notes. Escherich took all phases of the typical Rh. rothneyi under bark. Viehmeyer cites Overbeck as having taken the form which I have described as the subsp. johorensis from several nests in the dead twigs of mango (Mangifera) and in the bark of durion trees (Durio zibethinus), and Dr. Kalshoven has
sent me the following note in regard to the subsp. javana: "The Rhopalomastix (gl04) was collected from a sample of bark of a dying Mangifera indica, which was for- warded to our Institute at Buitenzorg by Dr. Loos, the land- bouwconsulent (agricultural expert) at Bondowoso (Res. Besoeki, Eastern Java). Dr. Loos wrote us that the ants were burrowing in the bark of the dying tree. The bark was riddled by the insects over half the circumference of the tree and at least as high as he could reach. Numerous pupae were seen. The ants, however, were not considered to be the cause of the death of the tree."
This note shows that the
Rhopalomastix colonies may be very populous. That Melis- sotarsus has very similar habits may be inferred from Arnold's remark (p. 190) on M. beccarii, which was taken at Durban, "nesting under bark in moderately populous colonies."




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100 Psyche [June
The affinities of the Melissotarsini to other tribes of Myrmicinse are very obscure. Fore1 at first regarded Rho- palomastix as allied to Solenopsis, but on receiving the worker at once recognized its close relationship to Melis- sotarsus. He believed, however, that "both genera are un- doubtedly primitive Myrmicines, allied to the Ponerine group Cerapachyi." In view of the extraordinary special- ization of the structural characters in both genera of Melis- sotarsini, this relationship can hardly be maintained. It was evidently suggested by purely superficial resemblances in general habitus to forms like Cylindromyrmex, Sirnopone, etc. which also burrow in wood. Emery, who had carefully studied Melissotarsus, when he came to revise the classifica- tion of the Myrmicinse for the "Genera Insectorum" (1921 p. 8) confessed his inability to establish the affinities of the Melissotarsini and a few other aberrant Myrmicine genera. He says: "Myrmicaria, Stereomyrmex, Cardiocondyla and especially the Melissotarsini are very specialized and isol- ated ants. In the present state of Myrmecology it is abso- lutely impossible to say anything about their affinities. I am of the opinion that the Melissotarsini are very prim- itive, but profoundly adapted to particular conditions of existence (thorax without sutures, antennae, lack of spurs, very small size, etc.). At any rate this group is very aber- rant." In the "Genera Insectorum" Emery placed the Melis- sotarsini next to the Stereomyrmicini, which they somewhat resemble. In my opinion there are also vague affinities be- tween the Melissotarsini and the Myrmecinini, especially in the wing-venation and the structure of the head of the male, though the mesonotum of the male Myrmecina possesses notauli which are absent in the Melissotarsini. In all probability the Melissotarsini, which now comprise only half a dozen species, are the last survivors of some very ancient Myrmicine stock. Their antiquity is attested by their rare and sporadic occurence in a rather circumscribed geo- graphic area. Evidently the Indomalayan genus Rhopalo- mastix is more primitive than Melissotarsus, which is known only from the warmer parts of Africa and Madagas- car. In both genera, however, the characters of the worker, particularly the diminutive size, compact, subcylindrical



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19291 The Ant Genus Rhopalornastix 101
shape of the body, the small eyes, reduced palpi, short, stout appendages, the flattened, club-like antenna1 funiculi, the peculiar shape of the mandibles and the coloration, all rem- iniscent of similar characters in the Scolytid and Platypodid beetles, represent so many specialized adaptations to a bur- rowing life in bark and dead wood. The tribe is, therefore, like certain tribes of Ponerine and Formicine ants and certain vertebrates such as the sturgeons among fishes, the ostriches among birds and the monotremes among mammals, a group of ancient but highly specialized and conservative species which have managed to survive in a narrow, con- stant environment.
A NOTE ON THE ASPARAGUS BEETLE,
CRZOCERZS ASPARAGI LINN.
In the summer of 1928 I examined some small apple trees planted in an asparagus bed in North East, Erie Co.,Pa. Great numbers of the asparagus beetle, Crioceris asparagi Linn., were present on the asparagus, and a large number of both sexes were resting and crawling about on the trunks and branches of the apple trees. Several rows of peach trees were also set in the asparagus bed, but I could find no beetles upon them, although the insects were apparently as num- erous on the asparagus between the peach trees as on that between the apple trees. No eggs of the beetle were found on the apple trees, the insects apparently only resting on the trees. Since the beetle is strongly positively phototropic, the fact that the apple trees were open with their branches shaded very little from the sunlight, while the trunks and branches of the peach trees were shaded by foliage, may, perhaps, account for the seeming preference of the aspara- gus beetle for the apple trees as resting places. MILTON F. CROWELL.




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