Ysachron, García & Botero & Santos-Silva, 2021

García, Kimberly, Botero, Juan Pablo & Santos-Silva, Antonio, 2021, A new genus of Achrysonini and new records in Cerambycidae (Coleoptera, Chrysomeloidea) from Colombia, European Journal of Taxonomy 735, pp. 89-109 : 91-92

Ysachron gen. nov.

urn:lsid:zoobank.org:act:B31E5244-31DC-49D7-8838-93850EEA9581

Figs 1–12

Type species

Ysachron pilosus gen. et sp. nov., here designated.

Differential diagnosis

Ysachron gen. nov. is similar to some genera of Hesperophanini Mulsant, 1839 , Oemini and Achrysonini . Despite not having the setae between ommatidia, we allocate it in Achrysonini due to the presence of the following characteristics: eyes coarsely faceted; antennomeres unarmed; antennae in males longer than body; scape shorter than antennomere III; procoxal cavities open and not strongly angulate laterally ( Fig. 13 , Ysachron pilosus gen. et sp. nov.; Fig. 14 , Achryson surinamum (Linnaeus, 1767)) ; prosternal process without lateral projections apically; and metatibiae not carinate.

The presence or absence of setae between ommatidia is a characteristic that also varies among subtribes of Oemini ( Martins, 1997) : present in Oemina Lacordaire, 1868 , absent in Methioidina Martins, 1997 (except in Proeme Martins, 1978 ).

Although we are aware of the great similarity between the tribes Achrysonini , Hesperophanini and Oemini , Ysachron gen. nov. differs from Hesperophanini and Oemini by having procoxal cavities not strongly angulate laterally ( Figs 13–14 ), while they are strongly angulate in the latter two ( Figs 15–16 ). The new genus also differs from genera of Hesperophanini by the median lobe with the apical region shorter than basal apophysis ( Figs 27–29 ).

Among the genera of Achrysonini , Ysachron gen. nov. is similar to Achryson by the rounded prothorax sides without projections, basal antennomeres linear, scape as long as half of the length of antennomere III, and fuscous aspect. It differs as follows: eyes lacking setae between the ommatidia; surface of the pronotum alveolate; antennae 12-segmented; elytra with long setae; and meso- and metafemora subclavate.Species of Achryson have setae between ommatidia, surface of the pronotum microsculptured, antennae 11-segmented, elytra with short setae, and femora fusiform. Also, unlike some other genera in Achrysonini , Ysachron gen. nov. does not show sexual punctation differences.

Etymology

The name Ysachron is an anagram of Achryson , a similar genus of Achrysonini . The gender is masculine.

Description

Head narrowed behind eyes, densely alveolate between upper eye lobes. Median groove well-marked between antennal tubercles. Antennal tubercles weakly elevated, with obtuse apex. Eyes coarsely

faceted, not coplanar with surface around them; without setae between ommatidia; upper eye lobes distant from each other; lower eye lobes large, about three times the length of genae. Genae small, with rounded apex. Labrum small, when together with clypeus, longer than frons. Mandibles short, with acute apex. Maxillary and labial palpi of similar length. Antennae 12-segmented, longer than body in males, as long as body in females; scape short, somewhat cylindrical, as long as about half length of antennomere III; antennomere III longer than IV. Prothorax subcylindrical; lateral margin rounded and unarmed, constricted in anterior and posterior margins. Prosternal process narrow, parallel sided, with apex curved inwards. Mesoventrite tumid. Mesoventral process emarginated at apex. Metaventrite rectangular, slightly wider than long, parallel-sided. Scutellum small. Elytra not exposing abdomen, parallel-sided; humeri rounded; base wider than posterior margin of prothorax; surface not carinate. Femora from subfusiform to slightly clavate. Tibiae slightly widened toward apex. Abdominal ventrite I the largest (including abdominal process), ventrites II–V subequal in length.

Key to South American genera of Achrysonini (modified and translated from Martins 2002 and Monné & Monné 2004)

1. Setae between ommatidia absent; antennae 12-segmented ................................. Ysachron gen. nov.

– Setae between ommatidia present; antennae 11-segmented ............................................................. 2

2. Sides of prothorax with long spine (longer than pedicel), with curved apex backward ..................... ................................................................................................ Drascalia Fairmaire & Germain, 1864

– Sides of prothorax unarmed (without spines or with small gibbosity) or at most with short triangular tubercle ............................................................................................................................................. 3

3. Pronotum with two tubercles on anterior third; elytra with longitudinal elevation, more evident near base, reaching apical fourth, delimiting a flattened area near suture .. Abyarachryson Martins, 2002

– Pronotum without tubercles (except for small gibbosities in some species of Achryson ); elytra uniformly convex or flattened on apical ¾ ....................................................................................... 4

4. Elytra flattened on apical ¾; metafemora linear ..................... Neoachryson Monné & Monné, 2004

– Elytra uniformly convex, metafemora not linear .............................................................................. 5

5. Metafemora strongly clavate ............................................................................................................ 6

– Metafemora subfusiform, with elongate club ................................................................................... 7

6. Antennomere III longer than scape and other antennomeres ...................... Huequenia Cerda, 1890

– Antennomere III shorter than scape and other antennomeres .............. Esseiachryson Martins, 2002

7. Elytra with contrasting punctures and glabrous perimeter ................... Cotyachryson Martins, 2002 – Elytra without contrasting punctures ................................................................................................ 8

8. Basal antennomeres thickened; sides of prothorax with small central gibbosity ............................... .......................................................................................................................... Cerdaia Monné, 2006

– Basal antennomeres linear; sides of prothorax rounded ................................................................... 9

9. Scape about as long or slightly shorter than antennomere III; elytra with long setae and shining aspect ...................................................................................................... Xenocompsa Martins, 1965

– Scape about as long as half the length of antennomere III; elytra often with short setae and general aspect not shining .......................................................................... Achryson Audinet-Serville, 1833

Figures

Figs 1–9. Ysachron pilosus gen. et sp. nov. 1–4. Holotype, ♂ (MPUJ_ENT 0071150). 1. Dorsal view. 2. Ventral view.3. Lateral view.4. Details of head, frontal view.5–8. Paratype, ♀ (MPUJ_ENT 0071152). 5. Details of head, frontal view. 6. Dorsal view. 7. Ventral view. 8. Lateral view. 9. Paratype, ♀ (MZSP). Dorsal view with sides of prothorax strongly rounded. Scale bars: 1–4, 6–9 = 0.5 cm; 5 = 0.25 cm.

Figs 10–16. 10–12. Details of pronotum of Ysachron pilosus gen. et sp. nov. 10. Holotype, ♂ (MPUJ_ ENT 0071150). 11. Paratype, ♀ (MPUJ_ENT 0071152). 12. Paratype, ♀ (MZSP). 13–16. Procoxal cavities in Cerambycidae Latreille, 1802 tribes. 13. Achrysonini Lacordaire, 1868, Ysachron pilosus gen. et sp. nov. 14. Achrysonini, Achryson sp. 15. Hesperophanini Mulsant, 1839, Hesperophanes sp. 16. Oemini Lacordaire, 1868, Oeme sp.

Figs 17–29. Ysachron pilosus gen. et sp. nov., ♂ (MZSP). 17. Tergite VIII. 18. Sternite VIII. 19. Dorsal arc. 20. Ventral arc. 21–23. Tegmen + median lobe. 21. Dorsal view. 22. Lateral view. 23. Ventral view. 24–26. Tegmen. 24. Dorsal view. 25. Lateral view. 26. Ventral view. 27–29. Median lobe. 27. Dorsal view. 28. Lateral view.29. Ventral view. Scale bars: 17, 20 = 0.5 mm; 18 = 0.3 mm; 19 = 0.1 mm; 21–29 = 1 mm.