Pseudastenus Bernhauer, 1933

Busanello, Dilson G. C., Irmler, Ulrich & Caron, Edilson, 2020, Revision of Pseudastenus Bernhauer, synonym with Xenasterides Newton and six new species (Coleoptera, Staphylinidae, Paederinae), Zootaxa 4755 (1), pp. 139-154: 140-141

publication ID

https://doi.org/10.11646/zootaxa.4755.1.6

publication LSID

lsid:zoobank.org:pub:D0B3FFA8-C262-4CD6-98AB-B46C55FCEF6D

DOI

http://doi.org/10.5281/zenodo.3728589

persistent identifier

http://treatment.plazi.org/id/03C887D5-FF8C-FF8C-83C6-FDEFC3B3F9ED

treatment provided by

Plazi

scientific name

Pseudastenus Bernhauer, 1933
status

 

Pseudastenus Bernhauer, 1933  

Pseudastenus Bernhauer, 1933: 520   (original description); Bierig, 1939: 180 (mention the similarity with Xenaster Bierig   ); Blackwelder, 1944: 127 (list of species); Blackwelder, 1952: 324 (nomenclatural notes); Bachmann et al., 2017: 14 (mention about type specimen in the MACN). Type species: Pseudastenus barretoi Bernhauer, 1933   (fixed by monotypy).

Xenaster Bierig, 1939: 179   (original description, preoccupied name, not Xenaster Simonwitsch, 1871   ); Blackwelder, 1944: 127 (list of species); Blackwelder, 1952: 405 (nomenclatural notes); Newton & Thayer, 1992: 62 (nomenclatural note); Navarrete-Heredia et al., 2002: 283 (nomenclatrual note, distribution); Bouchard et al., 2011: 221 (nomenclatural note); Asenjo et al., 2013: 280 (distribution). Type species: Xenaster plaumanni Bierig, 1939   (fixed by monotypy). New synonym.

Xenasterides Newton, 2017: 17   (replacement name for Xenaster Bierig, 1939   ). Type species: Xenaster plaumanni Bierig, 1939   (fixed by monotypy). New synonym.

Diagnosis. Pseudastenus   differs from the other genera of Lathrobiini   by having the following set of characters: head, pronotum and elytra with dense, microtuberculate, setiferous punctures; neck one-third as wide as head; antennae short, clavate, gradually widened from antennomeres 4 to 11; 11th antennomere equal in length to the three preceding antennomeres combined ( Fig. 2 View FIGURES 1–11 ); anterior margin of labrum deeply emarginate at the middle, with four denticles, medial two denticles robust and each one with two spine-like setae, each external denticle with one spinelike seta ( Figs. 8 View FIGURES 1–11 , 21 View FIGURES 21–29 ); gula very narrow and parallel sided; pronotum trapezoidal, slightly wider than long, enlarged in anterior third ( Fig. 15 View FIGURES 12–20 ); profurcasternum expanded caudally and laterally, almost contiguous with the pronotal hypomeron ( Fig. 16 View FIGURES 12–20 ); profemur enlarged ( Fig. 27 View FIGURES 21–29 ); protarsus not dilated; and metatibia with apical ctenidium on the posterior face.

Redescription. Male. Maximum body length 3.50 mm, humeral width 0.50 mm. Body elongate ( Figs. 36–37 View FIGURES 36–39. 36 , 40–45 View FIGURES 40–45 ); head and pronotum equal in width, elytra conspicuously narrower and abdomen tapering to apex. Head, pronotum and elytra with dense, microtuberculate, setiferous punctures, surface matt ( Figs. 1 View FIGURES 1–11 , 15, 18 View FIGURES 12–20 ); abdominal segments slightly glossier. Abdominal setae longer than those of the remaining body, length of setae gradually increasing to the apex. Head: wider at base than at front, shape trapezoidal ( Fig. 1 View FIGURES 1–11 ); basal margin with short medial emargination; neck one-third as wide as head. Antennae short, reaching the apical margin of pronotum; clavate, gradually widened from antennomeres 4 to 11; fine pubescence gradually increasing to apex; scape long, almost as long as four subsequent antennomeres combined; pedicel and antennomere 3 longer than wide, pedicel longer than 3rd; antennomere 4 subquadrate; antennomeres 5 to 10 wider than long; antennomere 11 almost two times longer than wide, length equal to the three preceding antennomeres combined ( Fig. 2 View FIGURES 1–11 ); antennomeres 9 to 11 with glandular pores ( Figs. 3–7 View FIGURES 1–11 ). Labrum transverse, with longitudinal median sulcus on the surface ( Fig. 8 View FIGURES 1–11 , 21 View FIGURES 21–29 ); anterior margin deeply emarginate at the middle, with four denticles, each medial two denticles robust and with two spinelike setae, each external denticles with one spine-like seta; lateral margin rounded. Mandibles symmetric, with three internal teeth, medial tooth shortest ( Figs. 9 View FIGURES 1–11 , 22 View FIGURES 21–29 ). Maxilla with short galea and lacinia, almost equal in length and densely ciliate ( Fig. 23 View FIGURES 21–29 ); palpomere 1 longer than wide; palpomere 2 three times longer than wide, enlarged to apex; palpomere 3 longest, almost three times longer than wide, asymmetric with protuberant internal margin; palpomere 4 shortest, very small and acute ( Figs. 10, 11 View FIGURES 1–11 , 23 View FIGURES 21–29 ). Mentum hexagonal; wider than long ( Fig. 12 View FIGURES 12–20 ). Labium with glossae subdivided in three dentate lobes, median lobe transverse and lateral lobes rounded ( Figs. 12, 13 View FIGURES 12–20 ); Hypopharynx with lobes of spinelike setae on anterior margin ( Fig. 14 View FIGURES 12–20 ). Labial palpomere 2 longest and six times longer 3 than palpomere 1, set of spine-like setae on the ventral margin of the internal face ( Figs. 12, 14, 17 View FIGURES 12–20 ); 3 narrowest, parallel sides and truncate apex; palpomere 2 and 3 with internal face conspicuously concave ( Figs. 14, 17 View FIGURES 12–20 ). Gula very narrow and parallel sides. Thorax: shape of pronotum trapezoidal ( Fig. 15 View FIGURES 12–20 ); anterior margin curved; posterior margin slightly curved. Anterior and posterior angles with macrosetae, anterior setae longer than posterior setae. Pronotal hypomeron with conspicuous superior line deflected ventrally to the anterior margin; joining the prosternal transverse carina ( Fig. 16 View FIGURES 12–20 ). Profurcasternum expanded caudally and laterally, almost contiguous with the pronotal hypomeron. Basisternum carinate and contiguous to the intercoxal carina ( Fig. 16 View FIGURES 12–20 ). Posterior margin of elytra emarginate. Hind wings well developed or short and poorly developed. Mesoventrite long, with the same length of metaventrite ( Fig. 19 View FIGURES 12–20 ); mesocoxae contiguous; mesoventrite process longer and sharper than metaventrite process. Tarsal formula 5-5-5; tarsomere 1 longest and 4 shortest ( Fig. 27 View FIGURES 21–29 ). Profemur enlarged ( Fig. 27 View FIGURES 21–29 ); metatibia with apical ctenidium on the posterior face. Abdomen: segments III–V parallel sided, VI–VIII tapering to abdominal apex. Segments III–VI with two pairs of paratergites, narrow and equally long as tergites ( Figs. 24–25 View FIGURES 21–29 ); segments VII–VIII without pair of paratergites, but with lateral lobes ( Fig. 26 View FIGURES 21–29 ). Tergite VIII with posterior margin pointed at the middle ( Fig. 28 View FIGURES 21–29 ); sternite VIII with posterior margin broadly rounded ( Fig. 29 View FIGURES 21–29 ). Tergite IX with long and symmetrical ventral struts ( Fig. 30 View FIGURES 30–35 ), anterior and posterior margin conspicuously emarginate at the middle; sternite IX three times longer than wide ( Fig. 31 View FIGURES 30–35 ), posterior margin rounded and median three-fifths fringed and pair of subapical macrosetae. Tergite X trapezoidal, anterior margin curved; latero-apical and posterior margin fringed, with two or three subapical macrosetae ( Fig. 32 View FIGURES 30–35 ). Aedeagus elongate, 3.7 to 5.9 times longer than wide; parameres not distinguishable; median lobe with two pairs of internal sclerites, the basal pair more robust than apical; and ejaculatory duct with two trifurcate sclerites (at least in P. plaumanni   and P. ribeirocostae   ) ( Figs. 46, 47 View FIGURES 46–47 ).

Female. Similar to male, except for tergite IX without ventral struts, almost totally divided longitudinally ( Fig. 33 View FIGURES 30–35 ); hemisternite IX with set of subapical macrosetae and posterior margin fringed ( Fig. 34 View FIGURES 30–35 ); tergite X similar to male, but with 4 anterior margin pointed ( Fig. 35 View FIGURES 30–35 ). Sclerotized spermatheca not found. The females should be identified by association with the male.

Geographical records. Mexico (Quintana Roo)   , Colombia (Risaralda)   , Peru (Huánuco)   , Brazil (Amazonas, Distrito Federal, Goiás, Rio de Janeiro, Paraná, Santa Catarina)   ; Argentina (Chaco, Jujuy, Missiones )   .

Remarks. The species of the genus are usually rare and found in restricted areas. They were usually collected in only small numbers at their sampling locations. Only P. plaumanni   seems to have a wider distribution from southeastern Peru to northern Argentina. According to information given by Lee Herman (AMNH), a higher number of species can be expected regarding the material deposited already in museums waiting to be described which can be also derived from species only present as female specimens for this study. As the information labelled to the studied specimens, the species of the genus live in the litter layer of rainforests. As two species groups could be differentiated one with normally developed elytra and hind wings and one with reduced elytra of hind wings, two groups with different ecologically demands can be separated. The first group with well-developed elytra certainly life in the upper humus layer of the forests, whereas the second group with reduced hind wings will prefer deeper humus horizons. Furthermore, the reduced flight ability indicates a low distribution ability and, thus, a more restricted distribution than in the group with well-developed hind wings. They may represent relict species which indicate former relict forest patches during ice age more even earlier geological eras. In particular more species of this group can be expected in mountainous regions such as in the Atlantic forest in Brazil or the eastern slope of the Andean range.

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Coleoptera

Family

Staphylinidae

Loc

Pseudastenus Bernhauer, 1933

Busanello, Dilson G. C., Irmler, Ulrich & Caron, Edilson 2020
2020
Loc

Xenasterides

Newton, A. F. 2017: 17
2017
Loc

Xenaster

Asenjo, A. & Irmler, U. & Klimaszewski, J. & Herman, L. H. & Chandler, D. S. 2013: 280
Bouchard, P. & Bousquet, Y. & Davies, A. E. & Alonso-Zarazaga, M. A. & Lawrence, J. F. & Lyal, C. H. C. & Newton, A. F. & Reid, C. A. M. & Schmitt, M. & Slipinski, S. A. & Smith, A. B. T. 2011: 221
Navarrete-Heredia, J. L. & Newton, A. F. & Thayer, M. K. & Ashe, J. S. & Chandler, D. S. 2002: 283
Newton, A. F. Jr. & Thayer, M. K. 1992: 62
Blackwelder, R. E. 1952: 405
Blackwelder, R. E. 1944: 127
Bierig, A. 1939: 179
1939
Loc

Pseudastenus

Bachmann, A. O. & Chani-Posse M. & Guala M. E. & Newton, A. F. 2017: 14
Blackwelder, R. E. 1952: 324
Blackwelder, R. E. 1944: 127
Bierig, A. 1939: 180
Bernhauer, M. 1933: 520
1933