Tropimenelytron Pace, 1983

Gusarov, Vladimir I., 2002, A revision of Nearctic species of the genus Tropimenelytron Pace, 1983 (Coleoptera: Staphylinidae: Aleocharinae), a new genus for North America, Zootaxa 114, pp. 1-24 : 3-11

publication ID

https://doi.org/ 10.5281/zenodo.155753

DOI

https://doi.org/10.5281/zenodo.6277326

persistent identifier

https://treatment.plazi.org/id/F207683E-6E3C-C40D-8C38-869CFAE0FB14

treatment provided by

Plazi

scientific name

Tropimenelytron Pace, 1983
status

 

Tropimenelytron Pace, 1983 View in CoL ( Figs. 1­21 View FIGURES 1 ­ 5 View FIGURES 6 ­ 11 View FIGURES 12 ­ 15 View FIGURES 16 ­ 21 , 35­64 View FIGURES 35 ­ 38 View FIGURES 39 ­ 44 View FIGURES 45 ­ 48 View FIGURES 49 ­ 54 View FIGURES 55 ­ 58 View FIGURES 59 ­ 64 )

Tropimenelytron: Scheerpeltz, 1955: 171 View in CoL (first record but unavailable name). Tropimenelytron Pace, 1983: 187 View in CoL .

Pelioptera (Tropimenelytron) View in CoL : Pace, 1991: 839.

Pelioptera (Tropimenelytron) View in CoL : Assing, 2000: 1000. Tropimenelytron: Assing, 2001: 168 View in CoL .

Diagnosis. Tropimenelytron can be distinguished from other aleocharine genera by the combination of the following characters: parallel­sided body; ligula with wide base, split apically ( Fig. 9 View FIGURES 6 ­ 11 ); pronotum subquadrate, with microsetae directed posteriorly along the midline of the disc (Type V, Benick & Lohse 1974) ( Fig. 12 View FIGURES 12 ­ 15 ); pronotal macrosetae moderately long; pronotal hypomera fully visible in lateral view; mesocoxae separated; medial macroseta of mesotibia as long as tibial width; tarsal formula 4­5­5; metatarsal segment 1 about as long as segment 2; one empodial seta; apical process of median lobe of aedeagus straight or slightly bent ventrally at the very apex (in lateral view; Figs. 41 View FIGURES 39 ­ 44 , 51 View FIGURES 49 ­ 54 , 61 View FIGURES 59 ­ 64 ); spermatheca without umbiculus ( Figs. 39 View FIGURES 39 ­ 44 , 49 View FIGURES 49 ­ 54 , 59 View FIGURES 59 ­ 64 ).

Tropimenelytron View in CoL differs from Geostiba Thomson, 1858 View in CoL in having ligula with wide base, separated mesocoxae and different shape of aedeagus and spermatheca.

Tropimenelytron View in CoL differs from Pelioptera micans Kraatz, 1857 View in CoL (the type species of Pelioptera Kraatz, 1857 View in CoL ) in the following characters: first segment of labial palpus with seta absent (present in P. m i c a n s); prementum with three asetose pores (two in P. micans View in CoL ), spermatheca without umbiculus; copulatory piece with short apical process (with very long flagellum­like apical process in P. m i c a n s) (see discussion below).

Tropimenelytron View in CoL differs from Earota Mulsant & Rey, 1874 View in CoL by smaller and narrower body; first segment of labial palpus lacking seta; shorter mesosternal process; incomplete infraorbital carina, less transverse pronotum and different shape of aedeagus and spermatheca.

Tropimenelytron View in CoL differs from Seeversiella Ashe, 1986 View in CoL in having pronotal pubescence of type V ( Benick & Lohse 1974); ligula with wide base; separated mesocoxae; posterior angles of male tergum 3 not extended as spines, and copulatory piece of aedeagus without long flagellum.

Description. Length 2.5­3.7 mm. Body parallel­sided, from uniformly brownish yellow to reddish brown with dark brown head and abdominal segment 6, and brown appendages.

Head slightly longer than wide; eyes small, temples 1.5­3 times as long as eyes; infraorbital carina short, not reaching posterior margin of eye. Antennal article 2 longer than article 3, articles 4­10 transverse ( Fig. 14 View FIGURES 12 ­ 15 ). Labrum ( Fig. 1 View FIGURES 1 ­ 5 ) transverse, anterior margin concave. Adoral surface of labrum (epipharynx) as in Fig. 2 View FIGURES 1 ­ 5 . Mandibles ( Figs. 3­ 5 View FIGURES 1 ­ 5 ) broad, right mandible with very small medial tooth; dorsal molar area with velvety patch consisting of tiny denticles (visible at 400x). Maxilla ( Figs. 6­8 View FIGURES 6 ­ 11 ) with galea extending slightly beyond apex of lacinia; apical lobe of galea covered with numerous fine and short setae; apex of lacinia with row of closely spaced spines, middle portion covered with numerous setae. Maxillary palpus with four segments ( Fig. 6 View FIGURES 6 ­ 11 ). Labium as in Figs. 9­ 11 View FIGURES 6 ­ 11 ; labial palpi with three segments ( Fig. 9 View FIGURES 6 ­ 11 ), first segment of labial palpus lacking seta ( Fig. 9 View FIGURES 6 ­ 11 ); ligula with wide base, split apically; medial area of prementum without pores or pseudopores, lateral areas with 3 asetose pores and single setose pore. Hypopharyngeal lobes as in Fig. 10 View FIGURES 6 ­ 11 . Mentum ( Fig. 11 View FIGURES 6 ­ 11 ) with slightly concave anterior margin, medial area with numerous pores.

Pronotum ( Fig. 12 View FIGURES 12 ­ 15 ) subquadrate, broadest at apical third, narrows posteriorly or with subparallel lateral margins; anterior margin straight, posterior margin convex; surface covered with microsetae directed posteriorly in midline, posteriorly and obliquely laterally in lateral areas (Type V, Benick & Lohse 1974); macrosetae moderately long; hypomera fully visible in lateral view. Meso­ and metasternum as in Fig. 13 View FIGURES 12 ­ 15 , mesosternal process short and wide, extended about 1/4 length of mesocoxal cavities, metasternal process about 1/3 length of mesocoxal cavities; mesosternum and mesosternal process not carinate medially; relative lengths of mesosternal process: isthmus: metasternal process in ratio of about 3:4:4; mesocoxal cavities margined posteriorly; mesocoxae separated. Medial macroseta of mesotibia as long as tibial width. Tarsal segmentation 4­5­5; metatarsal segment 1 about as long as segment 2 ( Fig. 15 View FIGURES 12 ­ 15 ). One empodial seta present. Wings fully developed (in Nearctic species). Posterior margin of elytra straight.

Abdominal terga 3­5 with moderately transverse basal impression. Tergum 7 ­ 1.1 times as long as tergum 6. Punctation on terga 6­7 slightly sparser than on terga 3­5. Tergum 7 with white palisade fringe.

Male secondary sexual characters include longitudinal carina along anterior half of sutural margin of each elytron, tiny medial knob at posterior margin of tergum 3, small medial knob at apical third of tergum 4, short medial carina in front of anterior margin of tergum 7 and uneven posterior margin of tergum 8 ( Fig. 35 View FIGURES 35 ­ 38 ). Some (smaller) males may lack these features altogether and externally look like females. Median lobe of aedeagus narrows apically (in parameral view; Figs. 40 View FIGURES 39 ­ 44 , 50 View FIGURES 49 ­ 54 , 60 View FIGURES 59 ­ 64 ), apex straight or slightly bent ventrally (in lateral view; Figs. 41 View FIGURES 39 ­ 44 , 51 View FIGURES 49 ­ 54 , 61 View FIGURES 59 ­ 64 ). Parameres with two long and two short macrosetae ( Figs. 44 View FIGURES 39 ­ 44 , 54 View FIGURES 49 ­ 54 , 64 View FIGURES 59 ­ 64 ). Copulatory piece of internal sac with short apical process and lateral denticles near the base of process (CP; Figs. 18, 20 View FIGURES 16 ­ 21 ). Medial lamellae (in parameral view) broad (ML; Figs. 17, 20­21 View FIGURES 16 ­ 21 ). Spermatheca without umbiculus, with thick C­shaped distal portion and thin proximal portion which may form 1­2 coils ( Figs. 39 View FIGURES 39 ­ 44 , 49 View FIGURES 49 ­ 54 , 59 View FIGURES 59 ­ 64 )

Type species. Geostiba tuberiventris Eppelsheim in Leder, 1879 by original designation.

Gender. The name Tropimenelytron ends in a Greek word “ ” transliterated into Latin without other changes and therefore takes the neutral gender (Article 30.1.2 of the Code; ICZN 1999). Because a species name must agree in gender with the generic name with which it is combined (Article 31.2.1) when G. tuberiventris is placed in Tropimenelytron the correct spelling is T. tuberiventre .

Discussion. Although originally described as a separate genus ( Pace 1983) Tropimenelytron was subsequently ( Pace 1991) downgraded to subgeneric rank within the genus Pelioptera . Pace (1991) argued that Pelioptera , Tropimenelytron and Geostibida have “almost identical” ligula, but in Pelioptera mesocoxae are more widely separated. Pace considered this similarity in ligula sufficient to include Tropimenelytron and Geostibida in Pelioptera as subgenera.

Pelioptera micans Kraatz, 1857 View in CoL ( Figs. 23­24 View FIGURES 22 ­ 26 , 27­29 View FIGURES 27 ­ 34 ; Fig. 9 View FIGURES 6 ­ 11 in Sawada 1980), the type species of Pelioptera View in CoL , differs from T. tuberiventre View in CoL and T. americanum Gusarov View in CoL , sp. n. in the following characters: first segment of labial palpus with seta present ( Fig. 23 View FIGURES 22 ­ 26 ) (absent in Tropimenelytron View in CoL : Fig. 9 View FIGURES 6 ­ 11 ) and equidistant from setae b and; prementum with two asetose pores ( Fig. 23 View FIGURES 22 ­ 26 ) (three in Tropimenelytron View in CoL : Fig. 9 View FIGURES 6 ­ 11 ), spermatheca with umbiculus ( Fig. 9 View FIGURES 6 ­ 11 , O in Sawada 1980) (without umbiculus in Tropimenelytron View in CoL : Figs. 39 View FIGURES 39 ­ 44 , 49 View FIGURES 49 ­ 54 , 59 View FIGURES 59 ­ 64 ), copulatory piece with very long apical process (flagellum­like; Fig. 29 View FIGURES 27 ­ 34 ) (with short apical process in Tropimenelytron View in CoL : Figs. 16, 18, 19­20 View FIGURES 16 ­ 21 ). Considering the above differences between the examined species of Tropimenelytron View in CoL (including the type species of the genus) and the type species of Pelioptera View in CoL I do not regard their similarity in the shape of ligula to be sufficient to include Tropimenelytron View in CoL in Pelioptera View in CoL . In this paper I consider Tropimenelytron View in CoL to represent a genus separate from Pelioptera View in CoL , pending a detailed examination of related genera and subgenera and analysis of their relationships.

My examination of three species of Pelioptera View in CoL ( Figs. 22­34 View FIGURES 22 ­ 26 View FIGURES 27 ­ 34 ) and comparison of the drawings and descriptions published by Sawada (1977, 1980, 1982, 1987, 1989) demonstrate that the species currently assigned to Pelioptera View in CoL often have very different structures of internal sac (cf. Figs. 29, 32, 34 View FIGURES 27 ­ 34 and Figs. 10 View FIGURES 6 ­ 11 , K; 11, I; 12, J in Sawada 1980) and mesometathorax ( Figs. 24­26 View FIGURES 22 ­ 26 ). This may indicate that some species currently assigned to Pelioptera View in CoL are not related and should not be congeneric with the type species of the genus. This problem requires further study and it is briefly discussed at the end of this paper.

In his key to subgenera of Pelioptera, Pace (1991) listed two characters to allow separation between Tropimenelytron and Geostibida : the difference in the shape of spermatheca (S­shaped in Geostibida and semicircular in Tropimenelytron ) and the length of elytra (shorter than pronotum in Geostibida and longer than pronotum in Tropimenelytron ). Unfortunately, these characters are not reliable. The shape of the proximal portion of spermatheca varies even among closely related species. For example, in T. americanum ( Fig. 39 View FIGURES 39 ­ 44 ) this portion is longer than in two other Nearctic species ( Figs. 49 View FIGURES 49 ­ 54 , 59 View FIGURES 59 ­ 64 ) and the spermatheca can be described as S­shaped. In many groups of Aleocharinae the length of elytra may be subject to variation even within the same species (see for example Muona 1991; Assing 1999). The specimens with well developed wings have longer elytra, while in wingless specimens the elytra are shorter. In many groups of aleocharines the species or populations restricted in their distribution to limited areas in the mountains often loose the ability to fly, have reduced wings and shorter elytra in comparison to their more widespread relatives in the plain. Clearly the length of elytra alone is not a sufficient character to separate subgenera of Pelioptera .

Pace himself is not consistent in applying these two characters to separate Tropimenelytron and Geostibida . For example, in T. nepalense Pace, 1985 a ( Fig. 45 View FIGURES 45 ­ 48 in Pace 1985a) and T. parbatense Pace,1987 a ( Fig. 47 View FIGURES 45 ­ 48 in Pace 1987a) (both assigned to Pelioptera (Tropimenelytron) in Pace 1991) the spermatheca is no less S­shaped than in G. himalayiensis Pace, 1984 (Fig. 108 in Pace 1991; assigned to Pelioptera (Geostibida) in Pace 1991). In P. (G.) problematica Pace, 1991 the elytra are both described (p. 849 in Pace 1991) and illustrated (Fig. 113 in Pace 1991) as being longer than pronotum, but nevertheless the species is placed in the subgenus Geostibida and not Tropimenelytron . In T. parbatense ( Fig. 46 View FIGURES 45 ­ 48 in Pace 1987a) elytra are illustrated as being shorter than pronotum, but in Pace 1991 this species is placed in the subgenus Tropimenelytron and not Geostibida . Some species assigned by Pace to Geostibida lack both diagnostic characters of Geostibida . For example, in P. (G.) eremita Pace, 1998 elytra are longer than pronotum (Fig. 133 in Pace 1998) and spermatheca is not S­shaped (Fig. 134 in Pace 1998).

Examination of Pace’s description of G. himalayiensis Pace, 1984 (type species of Geostibida ) and description of additional species included by Pace in Geostibida ( Pace 1984, 1985a, 1991, 1998) demonstrates that Geostibida is an artificial group which includes those species of Tropimenelytron ( G. himalayiensis Pace, 1984 ; G. major Pace, 1984 ; G. annapurnensis Pace, 1985 a) which have short elytra, and some unrelated species (which should be reassigned to other genera) with the same type of pronotal pubescence ( P. (G.) lii Pace, 1998 ; P. (G.) kowloonensis Pace, 1998 ; P. (G.) eremita Pace, 1998 and probably P. (G.) problematica Pace, 1991 ). A revision of the type of Geostibida is necessary to formally synonymize the name with Tropimenelytron .

The genus Tropimenelytron is being reported from North America for the first time.

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Coleoptera

Family

Staphylinidae

Loc

Tropimenelytron Pace, 1983

Gusarov, Vladimir I. 2002
2002
Loc

Pelioptera (Tropimenelytron)

Assing 2001: 168
Assing 2000: 1000
2000
Loc

Pelioptera (Tropimenelytron)

Pace 1991: 839
1991
Loc

Tropimenelytron:

Pace 1983: 187
Scheerpeltz 1955: 171
1955
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