William L. Brown, Jr. and Ronald G. Boisvert.
The Dacetine Ant Genus Pentastruma (Hymenoptera: Formicidae).
Psyche 85:201-208, 1978.

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THE DACETINE ANT GENUS
PENTASTR UMA (HYMENOPTERA: FORMICIDAE)'
BY WILLIAM L. BROWN, JR. AND RONALD G. BOISVERT Department of Entomology
Cornell University, Ithaca, New York 14853 The genus Pentastruma was established by Fore1 (loc. cit. infra) on the basis of a single Taiwanese worker specimen that he described (P. sauteri) as having 5 antenna1 segments, a very unusual number even for a member of the Dacetini, to which tribe he indicated that it belonged. In several ways, the description read as though based on a depilated species of Smithistruma, and when, several years ago, Dr. Masao Kubota sent specimens of a nearly hairless short-rnandibulate dacetine from Japan, WLB suspected that it might be close to Pentastruma sauteri, despite the fact that its antennae displayed the 6-rnerous condition usual in strurnigenite dacetines.
Now we have finally discovered the location of the Hans Sauter Collection of Taiwanese ants, in the Institut fur Pflanzenschutz- forschung (BZA) der Akadernie der Landwirtschaftswissenschaften der Deutsche Dernokratik Republic in Eberswalde. Through the kind offices of Dr. G. Morge we have been able to borrow some critical forrnicid types from the Sauter material, among them the unique specimen of Pentastruma sauteri. This worker proves to be close to the Japanese species received from Dr. Kubota, but it is specifically distinct. It does also have 6 antennomeres, with the normal strurnigenite proportions, and not 5 as stated by Forel. In its general form, P. sauteri is a rather typical Smithistruma, except for its complete lack of standing or other conspicuous hairs on head, trunk and petiole, and the new Japanese species matches it in these respects.
It seems logical that Pentastruma should eventually be merged with Smithistruma, but the latter genus is itself not stable at this 'A report of Research from the Cornell University Agricultural Experiment Station, New York State College of Agriculture and Life Sciences. The research was supported by National Science Foundation Grant GB-31662. Manuscript received by the editor September 15, 1978.



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202 Psyche [June-September
time, because new species have been discovered (mostly unpub- lished) that seem likely to link it with such senior genera as Trichoscapa and Codiomyrmex.
Until more of these new species have been formally described and properly analyzed, no firm classification of the short-rnandibulate strurnigenites is practicable. It seems best to retain some of the available generic names for now, if only to avoid excessive cornbina- torial changes as the classification develops. Accordingly, we retain the name Pentastruma for the time being. We figure for the first time the type species, P. sauteri, and
supplement its original description, and we describe a second species, P. canina, from Japan, based on all 3 castes. Measurements and proportions, and their abbreviations, are those standard in papers on Dacetini, e.g., Brown, 1953, Arner. Midi. Nat. 50: 7 ff., and 1973, Pacific Insects 15: 259. Pentastruma
>Pentastruma Forel, 1912, Ent. Mitt. 1: 50. Type species: Penrasrruma saureri Forel, monobasic.
Worker: Like Smithistruma in size, and form of head, mandibles and remainder of body, including the 6-rnerous antennae; small funicular segments I1 and I1 separate and distinct. Clypeus with median turnulus and broadly extended anterolateral apron; anterior margin concave in outline. Mandibles depressed, porrect, with rounded basal lamella and no diasterna, up to 15 acute teeth and denticles of varying length, including small apical tooth. Labrurn with 2 long, tapered lobes, as in Smithistruma. Body densely reticulate-punctulate and opaque (feebly shining in some views), but postpetiolar disc and gaster smooth and shining, except for basigastric costulae. Head, trunk, petiole and appendages without erect hairs, and even the pubescence reduced to a virtually invisible (at 50X) dilute vestiture of minute, appressed to decumbent hairs. The under-mouthparts have some small standing hairs. Postpetiole and gaster with a few short, blunt-tipped or rerniforrn, standing hairs, mostly arranged symmetrically. Color testaceous to light ferruginous.
Queen: Like the Smithistruma queen, but with differences cor- responding to those of the worker. Thoracic dorsurn with a few



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19781 Brown & Boisvert - Ant Genus Pentastruma 203 short, slender but stiff, erect hairs. Pronoturn with a flat, C-shaped, marginate dorsal platform; scutum rising abruptly above this. Male: As in Smithistruma.
Distribution as known: Japan (Honshu and southward); Taiwan. Almost certainly occurs on the Asian mainland, but not yet collected there.
Pentastrurna sauteri
Fig. 1
Pentastrurna sauteri Forel, 1912:51, worker. Type loc.: Pilarn, Taiwan. Holotype worker: TL 2.2, HL 0.62, HW 0.43, ML 0.06, WL 0.55 rnrn; CI 69, MI 10. The figure shows well the full-face outline view of head and mandibles. The head is shorter, with vertex more convex, than in P. canina, and the mandibles are shorter and more "set into" the anterior clypeal concavity. Although we have been unable to view the mandibular dentition directly and in detail in the lone holotype specimen, it seems that a rounded basal lamella is present, and that a series of sharp teeth follows without a diasterna. The number of teeth (12?) may be slightly smaller than in P. canina, and the sizes of the teeth seem to be more evenly graded. Viewed from the side, P. sauteri is much as shown in the side view of P. canina (Fig. 4), except that in sauteri, the upper vertex is more prominent, so that the head is thicker at this point dorsoventrally, and the transition from frontal to occipital faces of vertex more abrupt. The truncal dorsurn is more strongly sinuate in side view; the propodeal teeth are also shorter and less acute than in canina, and the propodeal lamella wider. The erect pilosity of the gastric dorsurn and apex is even more reduced, in hair number and size, than in canina. In the sauteri type, the middle of the rnesopleura is weakly shining, though still sculptured, and the dorsolateral rnar- gins of the trunk are completely lacking. P. sauteri still remains known only from this single specimen from Taiwan.
Pentastruma canina new species
Figs. 2, 3, 4
Holotype worker: TL 2.9, HL 0.77, HW 0.55, ML 0.16, WL 0.72, petiole L 0.30, eye L 0.05, scape L 0.32, hind femur L 0.46, hind tibia L 0.35 mrn; CI 71, MI 21.




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Psyche [June-September
Figures 1-4.
Pentastruma spp., workers. Fig. 1, P. sauteri holotype, head in full- face dorsal view. Fig. 2, P. canina new species, paratype from type nest series, head in full-face dorsal view. Fig. 3, same, side view. Fig. 4, same, another paranidotype, mandible greatly enlarged. Figs. 1-3 to same scale; scale line = 0.2 mm. Drawings by Ronald G. Boisvert.




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19781 Brown & Boisvert - Ant Genus Pentastruma 205 Habitus as shown for the paratype in Figs. 2 and 4. Note the depressed, flat mandibles and the 6-rnerous antennae, with segments proportioned as in Smithistruma, and also the broadly extended, sharp-edged, larnelliforrn, free lateral margins of the clypeus, trans- lucent in bright light. Mandibular armament shown in detail in Fig. 3. After the broadly rounded basal lamella there follow without a diasterna 15 teeth, of which the first, fifth, and ninth are the longest. Between these, 2 groups of 3 smaller teeth each, in each such triplet, the middle tooth a little longer than the 2 flanking it. A similar triplet follows the ninth tooth, and after this 2 small subapical teeth and a robust apical tooth. Labral lobes at rest extending beyond the rnidlength of the mandibles. Mandibular surface very finely sculp- tured, weakly sericeous-shining.
Pronoturn with rounded, strongly rnarginate anterior margin (excluding cervix), faintly indicated but rounded humeri, feebly marginate or subrnarginate dorsolateral margins, widest (W about 0.3 1 rnrn) behind rnidlength, tapering caudad into subparallel-sided posterior half of trunk (W about 0.16 rnrn across propodeal dorsurn), which even widens again very slightly caudad. Meta- notal groove obsolete or nearly so as viewed from above; pro- podeal teeth approximately parallel. Faint margins extend the length of the dorsolateral borders of the trunk, but these are visible only in certain views and lights.
Petiolar node subquadrate (rounded in front), slightly wider (W about 0.15 rnrn) than long, its dorsal surface with sculpture partly effaced, weakly shining. Postpetiolar disc transversely elliptical, nearly twice as wide as long (L 0.15, W 0.27 rnrn), smooth and shining, with a widely spaced pair of inclined hairs near posterior border. Gaster with weak basidorsal costulae, effaced rnesad, the longest extending about a quarter of the length of the first tergurn. Erect, feebly enlarged hairs: 4 near base of first gastric tergite, a pair near rnidlength, and a pair near posterior border of first tergite; remaining segments with 2 or 4 hairs each on tergites, and a few fine ventral, erect hairs also on apical half of gaster. The fine, short, extremely dilute, appressed and decumbent pubescence is invisible except at high magnifications (over 50X) and in special, strong lights, and is best developed on mandibles, antennae, vertex, legs, and gaster, though nowhere evident without a special effort to find it.
Color medium testaceous; spongiforrn apendages sordid whitish- testaceous.




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206 Psyche [June-September
Type deposited in the Museum of Comparative Zoology, Har- vard University.
Queen (Based on 7 specimens from 4 localities, including type nest series): TL 3.0-3.3, HL 0.77-0.80, HW 0.57-0.59, ML 0.17- 0.18, WL 0.80-0.84, forewing L (3 specimens) 2.4-2.6 mrn; CI 73-75, MI 22-23. Largest specimen (from Kiyosurniyarna, HL 0~80 rnrn) with scape L 0.33, eye L 0.13 rnrn. With the usual differences from the worker. Pronoturn with flat dorsal pronotal platform, as seen from above, markedly constricted before it joins the mesothorax. Scutellurn rounded and bulging caudad. Petiolar node broader than in worker, and tending to be rnedially sulcate in front. Scuturn irregularly reticulate-punctate, its surface weakly shining in some lights, opaque in others. Color testaceous to medium ferruginous, usually slightly darker than worker.
Male (3 specimens from Manazuru and Shiraharna): TL 2.7-2.8, HL 0.56-0.60, HW including eyes 0.45-0.47, eye L 0.20-0.22, WL 0.82-0.83, forewing L 2.3-2.4 rnrn.
Color blackish-brown, gaster dark reddish-brown, legs and an- tennae sordid, pale, dull brown; wings hyaline. Mandibles slender, each with a weak tooth-like angle apicad of rnidlength, only slightly curved, probably not opposable, tapered to a very acute apex. Labrurn broad, the 2 lobes short and separately rounded. Antenna1 scape broader and longer than pedicel, and about as broad as the apical antenna1 segment; segments I11 through XI1 slender and cylindrical, all longer than scape or pedicel. Pronoturn forming a flattened, C-shaped platform, something like that of female. Mesonoturn large and bulging; notauli present but short, and not meeting behind to form a V or Y; parapsidal lines present. Scutellurn bulging, rounded caudad. Propodeal teeth low, subacute, with narrow, concave infradental larnellae. Mesokatepisternurn and a patch on the side of the propodeurn with sculpture effaced, nearly or quite smooth and shining.
Petiole claviforrn, with low, rounded, scarcely differentiated node that is mainly smooth and shining above; spongiforrn appendages reduced to a narrow mid-ventral strip and a fine, cariniforrn posterodorsal collar. Postpetiole broader than long, rounded, smooth and shining, with a narrow, posterior collar of transparent lamella and an anteroventral spur trimmed narrowly with trans- parent lamella. Gaster unadorned at base, smooth and shining, with an extremely sparse, inconspicuous sprinkling of tiny, appressed



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19781 Brown & Boisvert - Ant Genus Pentastruma 207 pubescence hairs, and a very few obliquely erect, short, fine hairs on tergurn of basal segment, plus some more of these nearer the gastric apex. Legs with dilute, fine, inconspicuous, decumbent and ap- pressed pubescence. Head, trunk, antennae, legs and sides of petiole predominantly finely reticulate-punctulate, opaque, with the excep- tions noted above.
Paratypes: 38 workers, 8 queens (alate and dealate) and 2 males, all from JAPAN. HONSHU: Manazuru, Kanagawa Pref. (type local- ity), 3 nest series; 4 April 1968 (with males), 20 Oct. 1968, 5 Jan. 1973 (with winged queens), all leg. M. Kubota. Harnaoka, Shizuoka Pref., 15 Nov. 1976, leg. R. Egawa. Kiyosumiyama, Chiba Pref., 17 Aug. 1976, leg. T. Kannari. Shiraharna, Wakayarna Pref., 6 Jan. 1971 (with males), leg. M. Kubota. KYUSHU: Miyazaki-jingu, Miyazaki Pref., 18 July 1971, leg. M. Shindo. Deposited in the collection of Dr. Masao Kubota, at Odawara, Kanagawa Pref., Japan; in the Museum of Comparative Zoology, Harvard Univer- sity, Cambridge, Massachusetts, U.S.A.; and in the Department of Entomology, British Museum (Natural History), London. The variation of worker paratypes is most marked in body size, relative head width, acuteness and width of propodeal teeth and trailing larnellae, and in depth of ferruginous coloration, often varying to faded straw color (in callows?). TL 2.5-2.9, HL 0.68- 0.78, HW 0.48-0.56, ML 0.14-0.16, Eye L 0.04-0.06, WL 0.62-0.72 rnrn; CI 66-74 (mean 71 for n = 16), MI 19-22. P. canina, widespread in central and southern Japan, is readily distinguishable from P. sauteri by the form of the head and mandibles (Figs. 1 and 2). From the known Smithistruma and Trichoscapa species of eastern Asia, the canina worker may be separated by its head shape and by the total lack of standing pilosity on head, scapes and trunk.
Dr. Masao Kubota, of Odawara, Kanagawa Prefecture, Japan, deserves thanks, not only for the opportunity to study the many excellently prepared specimens of P. canina, but also for notes on the biology of the species summarized below. P. canina is an uncommon species, found in the Kant6 District and southward. It inhabits the floor of coastal evergreen broadleafed forest, which is generally subtropical. Nests are found in small pieces of rotten wood, rotten fallen branches, under moist leaf litter, or at a slight depth in the humus. The largest colony censused contained one queen and 57 workers.




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