Euspilotus (Platysaprinus) myrmecophilus ( Bickhardt, 1910 )

Lackner, Tomáš & Arriagada, Gerardo, 2020, Revision of Euspilotus, subgenus Platysaprinus, with description of two new species (Coleoptera: Histeridae), Acta Entomologica Musei Nationalis Pragae 60 (1), pp. 303-317 : 309-312

Euspilotus (Platysaprinus) myrmecophilus ( Bickhardt, 1910)

( Figs 23–33 , 56)

Saprinus myrmecophilus Bickhardt, 1910: 223 , Fig. 1 (original description). BLA CKWELDER (1944): 179 (catalogue).

Euspilotus myrmecophilus: BI CKHARDT (1916): 83 (catalogue); BLA CKWELDER (1944): 178 (catalogue).

Saprinus carinipennis Desbordes, 1924: 372 (original description). BLA CKWELDER (1944): 179 (catalogue), syn. nov.

Euspilotus (Platysaprinus) carinipennis : ARRIAGADA (1987): 68 (new combination); MAZUR (1997): 239 (catalogue); MAZUR (2011): 193 (catalogue).

Platysaprinus zikani Reichensperger, 1926: 194 , Figs 4–5 (original description); BLA CKWELDER (1944): 180 (catalogue).

Euspilotus (Platysaprinus) zikani : MAZUR (1984): 72 (catalogue);ARRIAGADA (1987): 68 (synonymy with E. (P.) carinipennis ).

Platysaprinus zikani var. daguerrei Bruch, 1931: 390 (original description). BLA CKWELDER (1944): 180 (catalogue); ARRIAGADA (1987): 68 (synonymy with E. (P.) carinipennis ).

Type localities. Saprinus myrmecophilus : Uruguay: Cerrito near Montevideo; S. carinipennis : Argentina: Misiones: Environs de San Ignacio, Villa Lutelia; Platysaprinus zikani : Brazil: Rio de Janeiro: Campo Bello; P. zikani var. daguerrei : Argentina: Buenos Aires: Rosas.

Type material examined. Saprinus myrmecophilus : HoLoTYP E:, glued onto a tip of a triangular mounting card, four segments of left metatarsus missing, genitalia extracted, disarticulated and placed into a small vial underneath the specimen, ‘ Montevideo | J. Tremoleras [black-margined, printed label] || Saprinus | myrmecophilus | n.sp. Bickh [written] || RLW | SEM, 1986 [yellow label, printed-written] || Type [red label, written] || Zool.Mus. | Berlin [printed] || HTLTToPffS | Saprinus | myrmecophilus | Bickhardt, 1910 | labelled by MNHUB 2004 [red label, printed]’ ( MFNB).

Saprinus carinipennis : HoLoTYP E: ♀, mounted on the tip of a triangular mounting point, four segments of left protarsus, two segments of right mesotarsus and four segments of both metatarsi missing, with the female genitalia placed in a small vial pinned under the specimen, ‘MU sEUM PARI s | MISITNES | Env. de San-Ignacio | Villa Lutecia | E.R Wagner 1910 [light-green label, printed] || S EPTEMBRE [printed] || JUIN [printed] || ToPE | unique [red label, printed-written] || Saprinus | carinipennis | n.sp. | H. Desbordes det. 1924 [printed-written]’ ( MNHN).

Platysaprinus zikani : SYNTYP Es:, glued onto rectangular mounting card, right antenna, left front leg and right metatibia missing, genitalia extracted and placed into a tiny vial under the specimen, ‘ [printed] || [rectangular mounting card with a glued specimen of Acromyrmex lundi] || Campo Bello | R. Jan. Zikán [written] ||Acrom. | Lundi | Guér [written] || Platysaprinus | Zikáni | Reichsp. [written] || Platysapr. | Zikáni | Reichensp. [black-margined, written label] || Coll. Reichensperger | Paratyp K [printed-written] || FICHADT [written]’ ( MACN); 1 spec., unknown sex, glued onto rectangular mounting card, right antennal club and right metatibia missing, with a specimen of Acromyrmex lundi glued onto a separate mounting card under the specimen, ‘Acromyrm. | Lundi [written] || Est.Rio.Jan | Brasil [written] || Cotypus [light-green label, printed] || Platysaprinus | Zikani | Reichensp.[written] || Platysaprinus | Zikani n.sp. | Reichensp. [written] || FICHADT [written]’ ( MACN).

Platysaprinus zikani var. daguerrei : 3 SYNTYP Es:sex unidentified, one of them lacking head, glued to the rectangular mounting cards, ‘RTSAS - F.C. Sud | Provincia de Buenos Aires | JUAN B. DAGUERRE [printed] || con Acromyrmex | ambiguus Em. [written] || Typus [light-green label, printed] || Platysaprinus | Zikani Reichsp.| v.Daguerrei Bruch | C. BRUCH DETERM [printed-written]’ ( MACN).

Additional material examined. ARGENTINA: BUENO S AIRE S: 1, 2 spec., with labels identical to those of Platysaprinus zikani var. daguerrei syntypes, but without any type labels ( CVMD); Buenos Aires, 1930, 1, Daguerre ( MSNG); Buenos Aires, Devoto, 24.vii.1928, 1 spec., S. J. Matúš lgt. ( CVMD).

Redescription. Body ( Fig. 23 ). PEL: 3.00–4.00 mm; APW: 1.30–1.70 mm; PPW: 2.00– 2.80 mm; EW: 2.50–3.00 mm; EL: 2.00–3.00 mm; oblong-oval, slightly convex, cuticle castaneous, elytra darker, almost black. Body appendages reddish-brown.

Head. Frons broad, almost as broad as long, faintly depressed medially, densely punctate, punctures separated by about 0.5–1.0 times their diameter; occipital stria complete; supra-orbital stria carinate, frontal stria widely interrupted, slightly continued on depressed epistoma, punctures on epistoma almost confluent. Mandibles apically acute, weakly punctate dorsally, punctation becoming denser laterally; subapical tooth on left mandible obtuse. Labrum weakly convex, finely punctate, labral pits adorned with two rather long labral setae. Rest of mouthparts not examined. Eyes slightly depressed, well visible from above; antennal scape thickened, on anterior face with two rather long setae, dorsally with 3–4 shorter amber setae; sensory structures of the antennal club not examined.

Pronotum ( Fig. 23 ) slightly broader than long across median line, anterior angles obtuse; marginal pronotal stria laterally slightly carinate, complete, weakened behind head; pronotal disc wholly punctate, punctures separated by approximately 2–3 times their diameter, becoming larger and denser towards pronotal base. Pronotal hypomeron asetose.

Elytra ( Fig. 23 ). Elytral epipleuron densely punctate, marginal epipleural stria thin, complete; marginal elytral stria carinate, complete, next to it a dense row of shallow punctures present, continues along elytral apex for short distance; apical elytral stria otherwise absent. Humeral elytral stria thin, present approximately on basal elytral fourth; inner subhumeral stria long, present as long fragment, basally almost connected to apex of humeral elytral stria, apically reaching approximately 4/5 of elytral length. Elytral striae 1–2 deeply impressed, carinate, surpassing elytral half apically; striae 3–4 shorter, reaching approximately elytral half apically (in case of holotype of S. carinipennis impressed only as thin elongate bulges); basal ends of all striae hooked inwardly. In holotype of S. carinipennis ( Fig. 23 ), next to fourth dorsal elytral stria conspicuous large elongate bulge present, elytral disc between it and elytral suture distinctly depressed, not observed in other specimens. Elytral suture of holotype of S. carinipennis elevated ( Fig. 23 ). Sutural elytral stria present as short weak fragment on apical elytral half, absent in holotype of S. carinipennis ( Fig. 23 ). Entire elytral disc covered by very dense almost confluent shallow punctures separated by less than half their own diameter, extreme elytral apex impunctate.

Propygidium with punctation similar to that of elytra; pygidium with sparser punctation; punctures separated by approximately their own diameter, becoming sparser and finer towards apex; lateral sides of pygidium slightly elevated, but not costate as in E. (P.) latimanus .

Prosternum ( Fig. 24 ). Tuter lateral costa of prosternum not reaching prosternal process, interrupted by prosternal cavity. Prosternal process strongly compressed, keel-like, covered with sparse elongate punctures; apically with two prosternal foveae connected anteriorly by well-impressed marginal prosternal stria. Carinal prosternal striae well impressed, divergent apically and terminating in prosternal foveae. Lateral prosternal striae short, carinate, attaining carinal prosternal striae at their approximate apical 4/5.

Mesoventrite ( Fig. 24 ). Marginal mesoventral stria complete; meso-metaventral stria absent, marked as row of large punctures in some specimens; disc of mesoventrite with punctures separated by their approximate diameter to twice their diameter.

Metaventrite ( Fig. 24 ) with variously dense punctures separated by their own to several times their diameter, along basal third large shallow and densely-packed punctures appear; lateral metaventral stria straight, carinate, shortened apically, not reaching metacoxa. Lateral disc of metaventrite with large, deep punctures separated by twice to three times their diameters; metepisternum with similar, though denser punctures separated by less than their own diameter.

First visible abdominal ventrite along basal third with rather large and dense punctures becoming smaller and sparser apically; disc striate laterally.

Legs. Protibia dilated, outer margin with four low teeth topped by short denticle, followed by 6–7 short denticles; protibial spurt short, rather thin, growing out from near tarsal insertion; tarsal groove rather shallow; protibial stria complete, next to it another thinner stria parallel to it present. Setae of outer row short, regular. Tuter part of posterior surface rugulose-lacunose; separated from smooth median part of posterior surface by thin and almost invisible stria; inner part of posterior surface smooth; posterior protibial stria complete, carinate.

Mesotibia dilated, outer margin with numerous short denticles, another row of closely set denticles present on anterior surface. Anterior surface of mesotibia faintly lacunose; anterior mesotibial stria complete. Metatibia dilated, similar to mesotibia.

Male genitalia. Tverall of similar morphology to those of E. (P.) latimanus . Sternite VIII ( Figs 25–26 ) widely separated medially; apex with large velum and brush of setae. Tergite VIII ( Fig. 26 ) outwardly arcuate; sternite VIII and ventrite VIII not joined laterally ( Fig. 27 ). Tergites IW and W ( Figs 28–29 ) similar to those of E. (P.) latimanus ; spiculum gastrale ( Figs 30–31 ) as well. Aedeagus ( Figs 32–33 ) stouter than with the preceding species, but generally similar to it.

Differential diagnosis. Differs from E. (P.) latimanus in the absence of the first dorsal elytral stria and the absence of a laterally costate propygidium . From E. (P.) ferreri sp. nov. differs in its entirely punctate elytra (basal half is impunctate in E. (P.) ferreri sp. nov.) and from E. (P.) vazdemelloi sp. nov. differs in its broadly oval body and its basally not abbreviated dorsal elytral striae (abbreviated in E. (P.) vazdemelloi sp. nov.).

Biology. Collected in nests of Acromyrmex ambiguus (Emery, 1888) and A. lundi (Guérin-Méneville, 1838); an apparent inquiline.

Remarks. ARRIAGADA (1987: 69) who examined the types of E. (P.) carinipennis , E. (P.) zikani and E. (P.) zikani var. daguerrei remarked that the type of E. (P.) carinipennis ( Fig. 23 ) represents an unusual (teratological H) specimen differing from the rest by the elevated elytral suture, depressed fourth elytral interval, absent sutural elytral stria and presence of elongate bulge next to fourth dorsal elytral stria. All other morphological characters are identical with the rest of the examined specimens.

BI CKHARDT (1910) explicitly mentioned that he had only one specimen of S. myrmecophilus . However, in the description he provided a length range of 3½– 4 mm, which is presumably erroneous. D EsBoRDEs (1924) also explicitly mentioned only one specimen of S. carinipennis . Hence both are considered holotypes by monotypy.

Saprinus carinipennis Desbordes, 1924 was first transferred into Euspilotus (s. str.) by MAZUR (1987: 65), and further into the subgenus Platysaprinus by ARRIAGADA (1987: 68), although without formal statement in the publication. Saprinus myrmecophilus Bickhardt, 1910 was treated as ‘ Euspilotus incertae sedis’ by MAZUR (1984, 1997, 2011).

BLA CKWELDER (1944) erroneously listed this species twice in his catalogue, once in Euspilotus (on p. 178) and then in Saprinus (on p. 179).

Distribution. Known from Argentina, Brazil, and Uruguay ( Fig. 56 ).

Figures

Figs 23–24. Euspilotus (Platysaprinus) myrmecophilus (Bickhardt, 1910). 23 –habitus, dorsal view (on the photo is the holotype of Saprinus carinipennis Desbordes, 1924); 24 – prosternum, meso- and metaventrite.

Figs 25–33. Male genitalia of Euspilotus (Platysaprinus) myrmecophilus (Bickhardt, 1910). 25 – VIII sternite and tergite, ventral view; 26 – ditto, dorsal view; 27 – ditto, lateral view; 28 – IW and W tergites, dorsal view; 29 – ditto, lateral view; 30 – IW sternite (spiculum gastrale), ventral view; 31 – ditto, lateral view; 32 – aedeagus, dorsal view; 33 – ditto, lateral view.

Figs 1–2. Euspilotus (Platysaprinus) latimanus (Schmidt, 1890). 1 – habitus, dorsal view; 2 – ditto, ventral view.

Figs 3–4. Euspilotus (Platysaprinus) latimanus (Schmidt, 1890). 3 – head, dorsal view; 4 – mentum.

Figs 5–7. Euspilotus (Platysaprinus) latimanus (Schmidt, 1890). 5 – labrum, dorsal view; 6 – mandibles, dorsal view; 7 – antennal club showing sensory structures of the antenna, dorsal view.

Fig. 56. Distributional map of the subgenus Platysaprinus Bickhardt, 1916 of the genus Euspilotus, 1907.