Memoirs on the Coleoptera/Volume 1/New Species of the Staphylinid Tribe Myrmedoniini/Tribe Myrmidoniini/Group Athetæ/Atheta/Micrearota
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Micrearota n. subgen.
Body very small in size, the eyes less developed than in more typical forms of Atheta, the middle coxæ well separated, the long ridge between the mesosternum and short angulate metasternum scarcely at all depressed and broadly convex, the mesosternal process short, with its apex very broad and truncate, nearly as in Stethusa. Additional characters of subgeneric import are mentioned in the course of the following descriptions. The species are rather numerous and appear to associate with ants but probably as mere casual guests:
| Atheta (Micrearota) loricula n. sp.—Moderately stout, feebly convex, not very shining, the micro-reticulation unusually coarse and strong, very coarse but feeble on the abdomen, the punctures fine, not dense and not rough; color piceous, the head and abdomen posteriorly slightly blackish, the elytra but little paler, the legs pale; pubescence not dense, rather coarse; head about as long as wide, the eyes small, anterior, the long tempora feebly swollen basally, the carinæ wholly wanting; antennæ moderately short and stout, distinctly incrassate, blackish throughout, the outer joints distinctly transverse, the last not quite so long as the two preceding, the second and third moderately elongate, obconic, the latter slightly the shorter; prothorax transverse, nearly as wide as the elytra, much wider than the head, widest before the middle, the sides broadly arcuate, the basal impression very feeble; elytra short and transverse, the suture feebly impressed throughout, but little longer than the prothorax, the apices not sinuate externally, the sides diverging; abdomen wide, only slightly narrower than the elytra, parallel, the fourth and fifth tergites equal, longer than the others, the first unusually short; hind tarsi rather long, slender, the first four joints uniformly though very slowly decreasing. Length 1.65 mm.; width 0.38 mm. Iowa (Iowa City). |
| Atheta (Micrearota) reperta n. sp.—Moderately stout and convex, strongly shining, the micro-reticulation very fine and nearly obsolete, moderately larger but feeble on the abdomen, the punctures very fine and rather sparse, wholly inconspicuous; pubescence somewhat coarse; color black, the pronotum piceous, the elytra but slightly paler, the legs pale piceo-testaceous; head rather transverse, parallel, the convex eyes larger, at scarcely more than their own length from the base, the tempora not swollen beyond them, the carinæ extremely fine, extending anteriorly a short distance from the base; antennæ blackish, moderately short, the joints from the fifth moderately stout and subparallel, transverse, the last gradually pointed, a little longer than the two preceding, the second and third moderately elongate, the latter only a little the shorter but more obconic; first joint stout; prothorax slightly wider than the head and a little narrower than the elytra, moderately transverse, the sides parallel and somewhat feebly, subevenly arcuate, unimpressed; elytra and abdomen nearly as in the preceding; hind tarsi slender, the basal joint much more elongate, almost as long as the next two. Length 1.65 mm.; width 0.35 mm. Iowa (Iowa City). |
The two specimens of this species were labeled by Prof. Wickham “Nest a.” I have placed with them a single example from Keokuk.
| Atheta (Micrearota) definita n. sp.—General form and coloration nearly as in reperta, shining, the reticulation obsolete, rather coarse but feeble on the abdomen, the punctures very fine, not close and not at all asperulate, the vestiture short and inconspicuous, head only a little wider than long, the eyes at about their own length from the base, the tempora slightly swollen and just visibly more prominent, the carinæ very fine, extending beyond the middle; antennæ nearly similar, the joints from the fifth rather stout, subparallel, transverse, the last arcuately pointed, fully as long as the two preceding, the first short and stout, the second considerably elongated, the third much shorter and strongly obconic; prothorax moderately transverse, a little wider than the head and much narrower than the elytra, the sides subparallel, almost evenly and moderately arcuate, unimpressed; elytra nearly as in the preceding, the abdomen relatively a little narrower and not so parallel, very feebly narrowing apically, the sides not so straight, very slightly arcuate, the tergites similarly proportioned; basal joint of the hind tarsi distinctly longer than the second. Length 1.6 mm.; width 0.33 mm. Texas (Austin). |
Allied rather closely to reperta but less parallel, the head and prothorax relatively smaller, the abdomen slightly narrower and not so parallel and the tempora more swollen. I have placed with the types two examples which I took at St. Louis, Mo. In neither case were they associated with ants so far as observed.
| Atheta (Micrearota) versuta n. sp.—Coloration and sculpture as in definita, very shining, the reticulation obsolete anteriorly, the minute punctures sparse; head nearly as long as wide, subquadrate, the eyes at more than their own length from the base, convex and prominent, the tempora swollen basally and distinctly more prominent than the eyes, the carinæ very fine, far from entire; antennæ nearly as in the preceding but less stout; prothorax only slightly transverse, distinctly wider than the head and narrower than the elytra, just visibly widest before the middle, the sides moderately and subevenly arcuate, unimpressed; elytra as in definita, the suture distinctly longer than the prothorax; abdomen very evidently narrower than the elytra, parallel, with straight sides, the fifth tergite not at all narrower but, if anything, wider than the first. Length 1.5 mm.; width 0.3 mm. Rhode Island (Boston Neck). |
A very small species differing from definita in the smaller and more convex eyes, more quadrate head, with the tempora more basally swollen and in its parallel abdomen; from repleta it differs in its smaller size, more slender form, relatively smaller head and prothorax, the former less transverse, narrower abdomen and shorter antennæ.
| Atheta (Micrearota) gregaria n. sp.—Form and coloration somewhat as in loricula but much more shining, the reticulation fine and subobsolete though evident, that of the abdomen disposed in feebly evident transverse broken lines; head relatively smaller than in loricula, the eyes larger and more convex though at rather more than their own length from the base, the tempora slightly swollen, the carinæ moderately short, unusually stout, the first three joints as usual, the outer joints transverse but with the ninth shorter than the tenth, the last much longer than the two preceding, gradually arcuate; prothorax moderately transverse, much wider than the head and distinctly narrower than the elytra, slightly widest near apical third but with the sides very broadly and subevenly rounded, unimpressed; elytra only moderately transverse, the suture much longer than the prothorax; abdomen only a little narrower than the elytra, parallel; first three joints of the hind tarsi decreasing rapidly in length, slender. Length 1.5-2.2 mm.; width 0.3-0.4 mm. Iowa (Cedar Rapids),—Brendel. |
This species is distinguishable from the three preceding by the smaller head and more evident though feeble micro-reticulation, and, from loricula, by the decidedly longer elytra and feeble sculpture.
| Atheta (Micrearota) pristina n. sp.—Moderately stout, very feebly convex, colored as in the preceding, the lustre moderately shining, the reticulation rather coarse and evident though feeble, the punctures minute and not dense; head about as long as wide, the eyes convex, prominent and well developed, as long as the tempora, which are not at all swollen and scarcely so prominent as the eyes, the carinæ vestigial and short; antennæ short and rather stout, slightly incrassate distally, the ninth and tenth joints mutually similar and transverse, the latter simply a little the larger, the last rather short and obtuse, not longer than the two preceding; prothorax small, only a little wider than long, very little wider than the head but very much narrower than the elytra, parallel, the sides feebly and subevenly rounded, unimpressed; elytra larger, much shorter than wide though very much longer as well as wider than the prothorax; abdomen narrower than the elytra, parallel; three basal joints of the hind tarsi decreasing moderately in length. Length 1.75 mm.; width 0.4 mm. Rhode Island (Boston Neck). |
Readily distinguishable by the relatively small head and prothorax and wide elytra; the eyes are more developed than usual and the tempora are not in the least inflated.
| Atheta (Micrearota) fecunda n. sp.—Coloration and fine indistinct punctuation as in the preceding, the reticulation small and feeble but more or less evident, that of the abdomen coarser byt feebler and, as usual, irregular; head nearly as long as wide, the eyes moderately convex, at a little more than their own length from the base, the swollen tempora slightly more prominent, the carinæ fine but long and entire or very nearly so; antennæ only moderately short, of the usual structure, stout except basally, the outer joints transverse, the ninth evidently shorter than the tenth, the last pointed at tip and about as long as the two preceding; prothorax rather transverse, much wider than the head and evidently narrower than the elytra, widest near apical third, the sides broadly rounded, straighter basally, unimpressed; elytra moderately short, transverse, the suture not impressed and materially longer than the prothorax; abdomen much narrower than the elytra, parallel, with straight sides; hind tarsi as usual, slender, the first three joints rapidly decreasing. Length 1.6-1.75 mm.; width 0.35 mm. New York (Catskill Mts.). |
DIstinguishable from any other species by the unusual development of the infra-lateral cephalic carinæ, which are frequently virtually entire though sometimes abbreviated, always however, so far as observed, extending well before the middle.
| Atheta (Micrearota) sana n. sp.—Rather stout, only feebly convex, colored as in the preceding species, shining, the fine reticulation feeble, the minute punctures not dense; pubescence rather coarse; head nearly as long as wide, the eyes well developed, at rather less than their own length from the base, the tempora parallel, feebly arcuate, not at all more prominent, the carinæ wholly obsolete; antennæ very stout, rather short, distinctly incrassate, the outer joints mutually similar in form, strongly transverse, the last pointed, stout, rather longer than the two preceding; prothorax unusually transverse, but little narrower than the elytra and much wider than the head, the sides almost evenly and moderately arcuate, unimpressed; elytra moderately transverse, much longer than the prothorax; abdomen distinctly narrower than the elytra, perfectly parallel, with straight sides; first three joints of the hind tarsi rapidly diminishing in length, slender as usual. Length 1.6 mm.; width 0.42 mm. Pennsylvania (Philadelphia). |
| Atheta (Micrearota) tincta n. sp.—Moderately stout and convex, the coloration nearly as in the preceding, shining, the reticulation feeble, the punctures very fine, sparse, notably closer and asperulate on the elytra; head as long as wide, the parallel sides evenly and broadly rounded, the eyes rather small, not prominent and anterior, the carinæ wholly obsolete; antennæ unusually long, about half as long as the body, moderately stout and only very gradually incrassate, the outer joints evidently wider than long though much less transverse than in the other species, the last large, stout, pointed, fully as long as the two preceding, the second and third alike, unusually elongate, the latter but very slightly the shorter; prothorax nearly as in sana but relatively a little smaller and shorter, much wider than the head; elytra short and strongly transverse, the suture only just visibly longer than the prothorax; abdomen rather wide, only a little narrower than the elytra, parallel, with straight sides, the first two tergites as usual, shorter than the next three and paler in color; hind tarsi long and slender, of the usual structure. Length 1.78 mm.; width 0.45 mm. New York. |
The species is an exception in the entire genus in its notably long antennæ. In this genus there are no distinct male sexual modifications so far as observable.