Isanopus sahlbergi Bernhauer, 1917

Klemann-Junior, Louri & Chatzimanolis, Stylianos, 2025, A new Amazonian species, description of male of Isanopus sahlbergi Bernhauer, 1917, and a revised key to species of Isanopus Sharp, 1876 (Coleoptera: Staphylinidae), Zootaxa 5575 (2), pp. 305-313 : 309-313

publication ID	https://doi.org/10.11646/zootaxa.5575.2.6
publication LSID	lsid:zoobank.org:pub:09D68B22-EDE1-4372-BDF2-E4CEFFF888F9
DOI	https://doi.org/10.5281/zenodo.14772728
persistent identifier	https://treatment.plazi.org/id/4E7987DF-7965-E933-58B7-F9D025E21203
treatment provided by	Plazi
scientific name	Isanopus sahlbergi Bernhauer, 1917
status

Treatment

Isanopus sahlbergi Bernhauer, 1917 View in CoL

( Figs 3A–D View FIGURE 3 , 4A–E View FIGURE 4 )

Examined material (5 ♂♂, 7 ♀♀).

Diagnosis (from Chatzimanolis 2008). Isanopus sahlbergi can be distinguished from all other known Isanopus species by the shape of the antennomeres. In I. sahlbergi the antennomeres are shorter than any other species and it can only be mistaken for I. eptaskouros ; however, in addition to the shape of the aedeagi, the two species can easily be distinguished by the coloration of abdominal segment VII, which is completely dark brown-black in I. eptaskouros . The meso and metatibia appear less enlarged in I. sahlbergi in comparison to other taxa in Isanopus .

Description. BL: 10.78 mm, FL: 5.63 mm.

Coloration. Head, pronotum and scutellum dark brown to black ( Fig. 3A–B View FIGURE 3 ). Antenna dark brown ( Fig. 3C View FIGURE 3 ). Legs dark brown; tarsomere 1 dark brown, tarsomeres 2–5 light brown, becoming lighter from the second to the fifth tarsomere ( Fig. 3A View FIGURE 3 ). Elytra ( Fig. 3A View FIGURE 3 ) dark metallic greenish blue. Abdomen ( Fig. 3A View FIGURE 3 , 4A View FIGURE 4 ) dark brown, almost black; except segment VII with anterior 4/5 dark brown and posterior 1/5 orange; and segments VIII–IX orange. Prosternum, meso- and metaventrite dark brown to black.

Head ( Fig. 3A–B View FIGURE 3 ) wider (HW: 1.76) than long (HL: 1.33), width: length ratio=1.32, with rounded hind angles. Head with long dark brown macrosetae along borders. Head with medium size umbilicate punctures each carrying dark brown microsetae; umbilicate punctures absent in middle and denser at the inner margin of eyes and posteriorly; punctures smaller around eyes and at base of head. Distance between punctures vary, from 0.5 to 1 times width of punctures. Integument of epicranium glossy, with dense microsculpture formed by transverse lines uniformly distributed; few micropunctures distributed at middle. Eyes prominent, length (OL: 0.62) about 1/2 the length of head, distance between eyes (IO: 1.21) about 4.2 times the width of eyes (OW: 0.29). Antennal segment ( Fig. 3D View FIGURE 3 ) 1 gradually club-like thickened; segments 1–11 longer than wide, with long macrosetae; segments 4–11 densely covered by microtrichae; segment 1 about twice as long segment 2; segment 3 about 1.5 times segment 2 length; segment 4 about 0.7 times segment 3 length; segments 5–10 almost identical, 1.6 times longer than wide; segment 11 subequal segments 5–10. Neck with few punctures and micropunctures; integument with dense microsculpture formed by transverse lines uniformly distributed.

Pronotum ( Fig. 3A–B View FIGURE 3 ) longer than wide (PL: 1.98; PW: 1.8), width: length ratio=0.91; pronotum broadest in apical 1/2 and narrower at basal angles; anterolateral angles obtusely rounded curved; from the anterolateral angle, the pronotum touches the neck through a smooth convex curve; lateral margins concave in dorsal view; pronotum flat in lateral view. Pronotum with dark brown microsetae and, along borders, few dark brown macrosetae. Medium size umbilicate punctures distributed in 4–5 rows; punctures absent on disc of pronotum; least distance between punctures for each row as wide as 1–2 punctures; distance between rows smaller towards anterolateral angles, distance between punctures as wide as 0.5–1.5 punctures. Integument of pronotum glossy, with dense microsculpture formed by transverse lines uniformly distributed and few micropunctures. Scutellum prominent, with dark brown microsetae, densely punctuate, distance between punctures as wide as 0.25–1 punctures. EL/PL ratio=1.17.

Elytra ( Fig. 3A View FIGURE 3 ) subquadrate (EL: 2.32; EW: 2.42), wider than pronotum; with medium size punctures; punctures smaller than head and pronotum; distance between punctures as wide as 0.7–1.6 punctures (about 7 punctures/ 0.5 mm); covered with dark brown microsetae and few long dark brown macrosetae along the lateral borders.

Legs ( Fig. 3A View FIGURE 3 ). Profemur with dark brown microsetae; protibia with light brown microsetae; protarsus dorsoventrally flattened, with yellow microsetae. Middle and hind legs with dark brown microsetae; mesotibia and metatibia with spines on the external side and with apical spurs; meso and metatarsus elongated and enlarged, with brown microsetae dorsally and light brown to yellow microsetae ventrally; tarsomeres 1–4 asymmetrical, apically dilated.

Abdominal ( Fig. 3A View FIGURE 3 ) segments III–VI with dense and uniform punctuation pattern; punctuation smaller than head, pronotum, and elytra; punctuation in each segment becoming less dense from anterior to posterior region. Tergite VII with punctuation becoming less dense from anterior to posterior region on anterior 4/5 (dark brown region), and denser punctuation on posterior 1/5 (orange region); sternite VII with punctuation becoming less dense from anterior to posterior region. Segment VIII with uniform distributed punctuation, sparser than previous segments. Each puncture with dark brown microsetae on segments III–VI and anterior 4/5 of segment VII; punctures with yellow microsetae on posterior 1/5 of segment VII and on segment VIII; few long dark brown macrosetae along borders of all segments. Lateral tergal sclerites of segment IX long and straight, covered with long brown and yellowish macrosetae. Abdominal tergites III–V with tergal basal carina and no subbasal (arch-like) carina. Posterior margin of sternite VII ( Fig. 4A View FIGURE 4 ) with shallow and broad emargination at midline; posterior margin of sternite VIII ( Fig. 4A View FIGURE 4 ) with deep V-shaped emargination at midline; sternite IX emarginate.

Aedeagus as in Figures 4B–E View FIGURE 4 . Paramere extremely reduced; paramere: median lobe ratio=0.3. Paramere in parameral ( Fig. 4C View FIGURE 4 ) and antiparameral (Fig, 4D–E) view with lateral outline slightly concave curved (Fig, 4D); with a smooth curve at the apex (Fig, 4D–E); without peg setae (Fig, 4D–E); with three long setae on each side of the apex (Fig, 4D–E). Median lobe in parameral view ( Fig. 4B View FIGURE 4 ) with lateral outline converging smoothly to a narrower rounded apex. Median lobe in lateral view ( Fig. 4C View FIGURE 4 ) in a slight downward curve; abruptly narrower in the apical 1/3; apex rounded.

Female (described in Chatzimanolis 2008). Similar to male, except by the posterior margin of sternites VII and VIII straight.

Habitat. Captured with Malaise trap. The capture sites in the state of Paraná is 1050 m.a.s.l. (São José dos Pinhais) and 750 m. a.s.l. (Telêmaco Borba). The vegetation is Evergreen Subtropical Forest “Floresta Úmida Subtropical” ( Holdridge 1987), in the transition between “Floresta Ombrófila Densa Montana ” and “Floresta Ombrófila Mista Montana ” (São José dos Pinhais), and “Floresta Ombrófila Mista Montana ” (Telêmaco Borba) ( Veloso & Góes Filho 1982). For details on climate, floristics and other data on collection sites in the state of Paraná, see Marinoni & Dutra (1991).

Distribution. Known distribution for Brazil, state of Rio de Janeiro (Petrópolis) and state of Paraná (São José dos Pinhais and Telêmaco Borba).

Revised key to the species of Isanopus (modified from Chatzimanolis 2008; figures starting with C refer to the figures in Chatzimanolis 2008):

1 Abdominal segments III–V dark orange to rufous or gradient between brown and orange............................ 2

- Abdominal segments III–V dark brown to black..........................................................… 3

2 Abdominal segments III–VIII dark orange to rufous; antennae dark brown; aedeagus as in Figures C5A–C ….......................................................................................... I. ashei Chatzimanolis, 2008 View in CoL

- Abdominal segments III–VIII with a color gradient from dark brown to yellow, usually III–IV dark brown, V–VI rufous to orange, VII–VIII orange to yellow; antennae orange to yellow; aedeagus as in Figures C7A–C …............................................................................................... I. hinojosai Chatzimanolis, 2008 View in CoL

3 Head punctuation on the posterior part of the head less dense, distance between punctures at least 0.5–1 times the size of puncture ( Figures C1B View FIGURE 1 ); paramere in dorsal view fairly wide but converging to two apical processes, with narrow U-shaped emargination between them ….......................................................... I. sallaei Sharp, 1884 View in CoL

- Head punctuation on the posterior part of the head almost confluent ( Figures 1B View FIGURE 1 , 3B View FIGURE 3 ); paramere not as above............ 4

4 Abdominal segment VII completely dark brown to black, aedeagus as in Figures C6A–C.................................................................................................... I. eptaskouros Chatzimanolis, 2008 View in CoL

- Abdominal segment VII orange or combination of dark brown and orange, aedeagus not as above..................... 5

5 Antennomeres 5–10 about 1.6 times longer than wide ( Figure 3C View FIGURE 3 ); median lobe without tooth ( Fig. 4B View FIGURE 4 ).............................................................................................. I. sahlbergi Bernhauer, 1917 View in CoL

- Antennomeres 5–10 at least two times longer than wide ( Figure 1C View FIGURE 1 ); median lobe with tooth (e.g., Fig. 2B View FIGURE 2 )............. 6

6 A ntennomeres 4–11 dark brown ( Fig. 1C View FIGURE 1 ); antennomeres 5–10 twice as long as wide ( Fig. 1C View FIGURE 1 ); paramere in parameral view expanded before apex, with rounded slightly bilobed apex ( Fig.1D–E View FIGURE 1 ).............................. I. itoupe sp. nov.

- Antennae 4–11 yellow ( Fig. C1A View FIGURE 1 ); antennomeres 5–10 2.5 times longer than wide ( Fig. C4D View FIGURE 4 ); paramere in parameral view not expanded before apex, apex straight with no apical processes (Fig. C9C)..................... I. tenuicornis Sharp, 1876 View in CoL