Discodon tricolor subsp. mimetic

Biffi, Gabriel & Geiser, Michael, 2022, A revision of Discodon tricolor (Guérin-Méneville) and its mimics from the Atlantic forests of Brazil (Coleoptera: Cantharidae), European Journal of Taxonomy 834 (1), pp. 148-189 : 181-183

publication ID	https://doi.org/ 10.5852/ejt.2022.834.1907
publication LSID	lsid:zoobank.org:pub:C2DF7AC2-3D99-43FF-BB36-CEF8E8747160
DOI	https://doi.org/10.5281/zenodo.7020075
persistent identifier	https://treatment.plazi.org/id/03CEA025-FFC6-FF91-FF24-FDD52B76FF47
treatment provided by	Felipe
scientific name	Discodon tricolor subsp. mimetic
status

Treatment

Key to the species of D. tricolor mimetic complex

Several species in different beetle families from the Atlantic Forest biome in Brazil show a similar colour pattern with a black body and elytra, a pronotum with orange lateral margins, and white to orangish elytral spots ( Fig. 17 View Fig ). This identification key distinguishes cantharid species with such a colour pattern, as well as similar species with entirely black elytra. Included in the key is the cantharid species Chauliognathus fenestratus (Perty, 1830) ( Fig. 17A View Fig ) which, despite belonging to a different subfamily ( Chauliognathinae ), is sympatric and may easily be confounded with species of D. tricolor mimetic complex.

1. Fronto-clypeal suture distinct; anterior and lateral margins of pronotum broadly arched; tibial spurs absent; tarsal claws always simple; last ventrite broad and strongly convex in males and flat and with a median parallel-sided notch in females ( Chauliognathinae , Chauliognathus View in CoL ) ................................ .......................................................................................... Chauliognathus fenestratus (Perty, 1830)

– Fronto-clypeal suture indistinct; lateral margins of pronotum slightly sinuous, males with a notch at posterior third ( Figs 7–8 View Fig View Fig ); tibial spurs present ( Fig. 9L View Fig ); anterior prothoracic tarsal claws lobed basally ( Fig. 9A–K View Fig ), posterior claws on meso- and metathoracic tarsal claws apparently split at the apex; last ventrite deeply divided into two halves in males ( Fig. 10 View Fig ), and entire, sometimes with median projections in females ( Fig. 15 View Fig ) ( Silinae , Discodon ) ........................................................... 2

2. Elytra with white or yellowish spots ................................................................................................ 3

– Elytra entirely black ........................................................................................................................ 12

3. Elytra with small and weakly defined rounded spots, legs reddish brown ( Fig. 4D, F View Fig ) ..................... ....................................................................................................................... D. testaceipes Pic, 1930

– Elytral spots large, legs entirely black .............................................................................................. 4

4. Antennae mostly black with some antennomeres clearer, or antennae mostly testaceous to light brown ................................................................................................................................................ 5

– Antennae entirely dark brown or black ............................................................................................ 7

5. Males: lobe of protarsal claws sinuate ( Fig. 9A–D View Fig ); aedeagus: ventral wall of tegmen short and broad, distal margin with two rounded lobes and a median notch ( Fig. 11 View Fig ). Females: distal margin of last ventrite sinuate, with short median projection ( Fig. 15A–C View Fig ) ..................................................... 6

– Males: lobe of protarsal claws broadly rounded ( Fig. 9J View Fig ); aedeagus ( Fig. 13D–F View Fig ): ventral wall of tegmen elongate, distal margin slightly concave medially. Females: distal margin of last ventrite broadly arched, without projections or notches ( Fig. 15J View Fig ) ..................... D. viridimontanum sp. nov.

6. Antennae mostly pale yellow to testaceous brown, except antennomere I or I and II. Males: lobe of protarsal claws slightly sinuate ( Fig. 9A View Fig ); aedeagus ( Fig. 11A View Fig ): ventral wall of tegmen longer, median lobe with a narrow central sclerite. Females: last ventrite with distal margin almost straight, with a slight median projection ( Fig. 15A View Fig ) .............................. D. tricolor (Guérin-Méneville, 1832)

– Antennae with last two or three antennomeres orange to light brown. Males: lobe of protarsal claws with a distinctly projecting lobule ( Fig. 9C View Fig ); aedeagus ( Fig. 11G–I View Fig ): ventral wall of tegmen less distinctly narrowed laterally, central sclerite of median lobe broader. Females: last ventrite with distal margin sinuate ( Fig. 15C View Fig ) ............................................................................. D. vanini sp. nov.

7. Elytra with weakly defined costae, more visible anteriorly ( Fig. 3D View Fig ); elytral spots rounded, dark yellow to orangish; antennae without lines ............................................. D. aurimaculatum sp. nov.

– Elytra smooth, without costae; elytral spots variable; antennae with or without lines ..................... 8

8. Pronotum black with dark reddish-brown markings at the angles ( Fig. 7G View Fig ) ...................................... ...................................................................................................................... D. marginicolle sp. nov.

– Pronotum with a broad longitudinal black band with irregular yellow and orange markings at the sides .................................................................................................................................................. 9

9. Pronotum distinctly narrower than humeri, about 1.3 times as wide as long ( Fig. 7K View Fig ). Males: hind leg strongly modified, coxa with unciform projection, femur swollen and tibia flattened distally ( Fig. 9L View Fig ); antennomeres VIII–XI with antennal lines ( Fig. 6K View Fig ); lobe of protarsal claws with broadly rounded margin ( Fig. 9K View Fig ); last ventrite broad, inner margins of halves notched, divergent, exposing the aedeagus ( Fig. 10K View Fig ); aedeagus with ventral wall of tegmen with a long median projection ( Fig. 13G–J View Fig ) ............................................................................................. D. crassipes Wittmer, 1952

– Pronotum wider, nearly or as wide as humeri. Males: hind leg slender, not modified; antennomeres with or without antennal lines ......................................................................................................... 10

10. Elytral spots somewhat triangular, elongate, extending anteriorly and posteriorly ( Fig. 3A View Fig ). Males: antennomeres without antennal lines ( Fig. 6B View Fig ); lobe of protarsal claws with sinuate margin ( Fig. 9B View Fig ); last ventrite elongate, inner margins of halves nearly parallel ( Fig. 10B View Fig ); aedeagus with ventral wall of tegmen short and broad, distal margin with a pair of rounded lobes and a median incision ( Fig. 11D–F View Fig ). Females: distal margin of last ventrite sinuous, with a short projection medially ( Fig. 15B View Fig ) .................................................................................................... D. neoteutonum sp. nov.

– Elytral spots smaller and rounder. Males: antennomeres with or without antennal lines; aedeagus elongate, distal margin of ventral wall of tegmen greatly projected. Females: distal margin of last ventrite with a pair of projections and a median V- ou U-shaped incision ( Fig. 15E–F, H–I View Fig ) ........11

11. Males: antennomeres without antennal lines ( Fig. 6I View Fig ); last ventrite elongate, distal margins of halves truncate, inner margins broadly separated, exposing part of aedeagus and meeting distally ( Fig. 10I View Fig ); aedeagus: distal margin of ventral wall of tegmen triangular, with an acute apex ( Fig. 13A–C View Fig ). Females: distal margin of last ventrite with two short projections and a median V-shaped notch ( Fig. 15I View Fig ) ................................................................................................................ D. tamoio sp. nov.

– Males: antennomeres IX–XI with antennal lines ( Fig. 6E View Fig ); last ventrite broad, distal margins of halves rounded, inner margins almost parallel ( Fig. 10E View Fig ); aedeagus: distal margin of ventral wall of tegmen with a pair of short and truncate projections, and a very long and curved median projection ( Fig. 12A–C View Fig ). Females: distal margin of last ventrite with two long projections and a median U-shaped notch ( Fig. 15E View Fig ) ............................................................................ D. lineaticorne sp. nov.

12. Antennae mostly orangish to light brown; head much narrower than pronotum, eyes prominent ..... ......................................................................................................................................................... 13

– Antennae dark brown to black; head broad, nearly as wide as the pronotum ( Fig. 5E–F View Fig ); eyes not prominent .............................................................................................. D. nigrocephalum Pic, 1949

13. Elytra narrower, nearly parallel, with weakly defined costulae ( Fig. 5D View Fig ); pronotum transverse, anterior margin nearly straight ( Fig. 7H View Fig ); antennae black at the base, clearing towards the apex; aedeagus elongate, distal margin of ventral wall of tegmen with a flat median projection and lateral sinuous lobes ( Fig. 12J–M View Fig ). Females: distal margin of last ventrite with two long projections and a median U-shaped notch ( Fig. 15H View Fig ) .......................................................... D. tenuecostatum sp. nov.

– Elytra wider, rough, without weakly defined costulae ( Fig. 5A View Fig ); pronotum with anterior and lateral margins broadly arched ( Fig. 7D View Fig ); antennae mostly light brown to orangish; aedeagus short, distal margin of ventral wall of tegmen with a median incision ( Fig. 11J–L View Fig ). Females: last ventrite short, distal margin sinuous, not strongly projected posteriorly ( Fig. 15D View Fig ) ................................................. ......................................................................................................... D. obscurior Pic, 1906 stat. nov.