Carl H. Lindroth.
The Male of Platypatrobus lacustris Darlington (Coleoptera: Carabidae).
Psyche 69(1):7-10, 1962.

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THE MALE OF PLATYPATROBUS LACUSTRIS
DARLINGTON (COLEOPTERA : CARABIDAE)*
BY CARL H. LINDROTH
Zoological Institute, University of Lund, Sweden The discovery of a new genus among the Patsobini from Lake Superior (Darlington, 1938) was most unexpected. It was founded on a single female from Batchawaung Bay, Ontario, in the Leconte collection in the Museum of Comparative Zoology at Harvard, and, in the absence of a male, the author hesitated to state the true relation- ship of the new genus. This female is the only specimen of the genus Platypatrobus (species, lmustris Darl.) heretofore known. Quite recently, in September, 1961, Dr. Darlington and I visited the well-known coleopterist, Mr. C. A. Frost, Framingham, Mass., and, looking through, his large collection, made the exciting discovery of a male of Platypatrobus lacustris, received by him from Dr. A. E- Brewer. According to the label, the beetle had been taken at "black light," July 30th, a few years ago (exact year not stated) at Sinclair in northernmost Maine. Its capture in a light trap and its well developed hind-wings indicate that it is able to fly. The new male, except for the two dilated basal segments of the pro-tarsi, matches the type completely. The extra setae on prothorax and elytra are considerably irregular in number and position: lat- erally on the prothorax are 3 ((left) and 4 (right) (in the type 4 + 3) setae; on the elytra, 1st interval, 2 -1 2 (type I + 2), 31-d interval, 12 + approxin~ately g
(type I I + 12), 5th interval, 10 + 8 (type 5 +6).
I was allowed to borrow the specimen and have dissected the genitalia (fig. I). The florameres are of the normal Patrobine type, almost identical with those of the two related genera, Palrobus and Diplous [Platidius), that is, appioximately symmetric with long, narrow apical prolongations bearing 4 setae at tip. The accessory sub- apical setae are inconspicuous, only 2 in number, and there is no suggestion of the hairy membrane externally that is characteristic of the septentrionis group of Patrobus,
The penis (median lobe) is non-sclerotized dorsally, as in Patrobus and Diplous, but not entirely open, as in Deltomems, Platidiolus (Patroboidea), and related genera. The hook-shaped basal part is a common feature of all Patrobini. The apex is long and slender as *Manuscript received by the editor October 26, 1961.



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8 Psyche [March
in Patrobus longicornis and foveocollis, but without the subapical left side tooth of longicornis and, compared with foveocollis, symmetric. The shape of the apex, however, generally has little generic value in carabid beetles.
The internal sac of the penis is less complicated than in most Patrobus. The "apical plate" ( Darlington ; "Manschette", Kuhnelt, 1941), forming the bottom (anterior part) of the eversible sac when in repose, is slightly spiral, but not at all to the extent of the sibiricus group of Diplous (Kuhnelt). It is not prolonged into a spine, as in the North American Diplous (contrasted with the Siberian repre- Fig. 1. Platypatrobus lacustris Darl. Penis (c) and parameres (a, right; b, left).
The dark parts of the internal sac are not isolated sclerites but thickened margins of lamellae.
sentatives of the genus). It lacks accessory spine (s) , in contrast to Patrobus. Presence of spines was used as a generic character of Patrobus by Darlington, but there is no spine in the Palaearctic P. assirnilis Chd.
The most characteristic feature in the internal sac of Platypatrobus is the dorso-basal part of the "apical plate", which protrudes into



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19621 Lindroth - Platypatrobus 9
the softwalled section of the dorsum. In side view it resembles a stalked button, but in dorsal view it is revealed as the side-face of a horizontal though somewhat elevated and irregular lamella with thickened margin. It seems to have no direct counterpart in any species of Patrobus or Diplous.
In summary, the male genitalia of Platypatrobus provide no clue to its taxonomic relationship with its two closest relatives, Patrobus and Diplous. The intrageneric variation of the internal sac is so great in both genera that no single consistently separating detail could be discovered. And the male genitalia of Pidtypatrobus itself show little peculiarity. Possibly, the general simplicity of the internal sac, with complete lack of spine-like sclerites, could be regarded as a sign of primitive organization. But it should be remembered that the same applies to the dJe,pressus group of Diplous (Ktihnelt, 1941) as well as to Patro bus assimilis.
The taxonomic position of genus Platypatrobus, therefore, has still to be judged on external characters. In these, the genus is clearly closer to Patrobus than to Diplous. This is shown by the protruding eyes and the strongly constricted neck, as well as by several structural details of the prothorax: the central furrow is deepened at base; the basal foveae are deep and well defined; the front mtargin is strongly elevated (almost as in P. longicornis), delimited basad by a deep transverse impression which is coarsely punctured (as in P. septen- trioinis) and prolonged laterally to front-angles as an engraved line (as in P. longicornis, septentrionis, and foveocollis) . However, as in Diplous, there is no defined latei-o-basal carinula inside the hind angles. There are also good characters separating Patrobus and Diplous in the marginal region of the elytral, not observed by earlier students (Darlington, 1938 ; Kuhnelt, 1941 ; Lindroth, 1961 ) : ( I ) the raised lateral bead is complete to apex in Patrobus, rather suddenly dis- appearing well before apex in Diplous? (2) the 9th stria is better
developed in Dtplous, still evident at the level of the meso-coxae, whereas in Patrobus it disappears anteriorly well behind this point; (3) the marginal row of setiferous punctures (on 9th interval) is almost continuous in Diplous, consisting of about 20 (19-24) punc- tures, whereas in Patrobus it is å interrupted at middle and the number of punctures is reduced (8-14). Jeanne1 ( I 941, p. 565ff) 'Studied in the North American and (Patrobus) Scandinavian representa- tives of the two genera.
This, however, is not quite constant in Diplous. An apparently undescribed species from the Kolyma River district, E. Siberia (V. N. Kurnakov). has
the elytra margined to apex.




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10 Psyche [March
has used the last character as the main distinction between the "sub- families" Deltottzeritae (represented in North America by genus Platidiolus, syn. Patroboidea) and Patrobitae, in spite of the fact that Diplous is referred to the latter group which he defines as having constantly 8 setifei-011s punctures ! In the three points mentioned above ( I-3), Platypatrobus agrees with Patrobus in points I and 2 but is intermediate in point 3, the marginal row consisting of 16 punctures on each side in the male investigated and being less inter- rupted at middle than in Patrobus.
Platypatrobus, though generically distinct, is closely allied to Patrobus and no "missing link" to Diplous. Its extreme rarity and restricted distribution undoubtedly give the impression of a relict, on the verge of extinction.
On the other hand, it does not seem
possible to tell whether Platypatrobus is the phylogenetically older genus. It should perhaps be regarded as "more simple" in general construction (lack of prothorax carinula, nearly continuous marginal row of setiferous punctures of elytra, simple internal sac of penis), but evolution sometimes goes toward simplification. How often is it actually defensible to state, without fossil evidence, what is "pi-imi- tive" and what "derivative"?
DARLINGTON, P. J., JR.
1938. The American Patrobini (Coleoptera, Carabidae). Entomologica Americana (Brooklyn) (new series), 18 : 13 5-183. JEANNEL, R.
1941. Coleopt6res Carabiques, 1. Faune de France (Paris), 39 : 1-571. KUHNELT, W.
1941. Revision der Laufkzfergattungen Patrobus und Diplous. Ann. Naturh. Mus. (Wien), 51 : 151-192.
LINDROTH, C. H.
1961. The Ground-Beetles (Carabidae, excl. Cicindelinae) of Canada and Alaska, 2.
Opusc. Ent. (Lund) , Suppl. XX : 1-200.




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