Triarius Jacoby 1887
Creators: name: Clark, Shawn M.
name: Anderson, E. Russell
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Chrysomelidae
Triarius

description: Triarius Jacoby, 1887
Figs. 2a–i, 3a–g
Triarius Jacoby 1887: 571
Type Species. Triarius mexicanus Jacoby, 1887 (by monotypy).
Diagnosis. The basal carina of the pronotum is complete. Although fine, it extends without interruption along the entire posterior margin. Each eye is narrowly separated from the base of the mandible by a distance subequal to the width of the
basal maxillary palpomere. The length of the basal antennomere is subequal to the maximum diameter of the eye. The epipleuron is broad in the basal portion and very narrow in the distal portion. Each tibia is armed with a terminal spur. The rectangular lobe at the apex of the male abdomen is conspicuous. In these characters, Triarius is similar to Triariodes. However, the frontal tubercles of Triarius are only about as broad as long, being limited laterad by a shallow (sometimes rather inconspicuous) depression. In Triariodes, the depression is nearly absent, such that the tubercles are strongly transverse, closely approaching the eye. Moreover, the aedeagus of Triarius is symmetrical, with the distal portion only weakly spatulate, or not at all.
Comments. Within the subfamily Galerucinae, the nature of the tarsal claws (simple, appendiculate, or bifid) is extensively employed to diagnose genera or even taxa above the generic level. It is therefore remarkable that some species of Triarius have bifid claws and others have appendiculate claws. However, this situation is not unique among the New World genera in the section Scelidites, where claws are reported to be appendiculate, except in some species of Triarius. Although not previously reported in the published literature, the claws are also bifid in Scelida metallica Jacoby, while appendiculate in all other species of Scelida Chapuis. Beyond the section Scelidites, the lack of claw uniformity is not common, but also not unprecedented. For instance, all species of Erynephala Blake and some (but not all) species of Monoxia LeConte have bifid claws in males and simple claws in females. In males of Hyperbrotica Bechyné and Springlová de Bechyné, all claws are appendiculate in females, while only the hind claws are appendiculate in males, the others being bifid.
KEY TO THE KNOWN SPECIES OF TRIARIUS
1. Tarsal claws bifid, inner lobe of each claw sharply pointed and forming angle less than 45° ................................................... 2
1´. Tarsal claws appendiculate, inner lobe of each claw blunt and forming angle greater than 45° .................................................... 6
2. Elytra uniformly colored or with contrasting color limited to the sutural and lateral areas, without stripe extending from humerus to base of distal declivity ................................. 3
2´. Elytra with stripe extending from humerus to base of distal declivity .......................... 4
3. Prothorax and elytra entirely black; gender male; aedeagus as in Fig. 3b; habitus as in Fig. 2d ........................... Triarius nigroflavus Riley, Clark, and Gilbert
3´. Prothorax and elytra largely or entirely yellow; gender male or female; aedeagus as in Fig. 3d; habitus as in Fig. 2g ............................... ...................... Triarius lividus (LeConte)
4. Basal half of elytron with short, oblique stripe between sutural stripe and posthumeral stripe; aedeagus as in Fig. 3e; habitus as in Fig. 2c ... ............................ Triarius trivittatus Horn
4´. Elytron without short stripe between sutural and posthumeral stripe .......................... 5
5. Distal half of hind femur mostly pale; terminal abdominal sternite entirely pale, or nearly entirely dark, not mostly pale with only narrow apical margin dark; gender male or female; aedeagus as in Fig. 3c; habitus as in Fig. 2f ............................. ............ Triarius melanolomatus (Blake)
5´. Distal half of hind femur mostly black; terminal abdomen sternite mostly pale, but narrowly dark apically; gender female; habitus as in Fig. 2e ................. Triarius nigroflavus Riley, Clark, and Gilbert
6. Head black; female elytra orange-yellow, with suture very narrowly black (Fig. 2b); male elytra entirely black (Fig. 2a); legs entirely black; aedeagus strongly curved in lateral view (Fig. 3a) ............. Triarius pini (Schaeffer)
6´. Head yellow; elytra yellow, except for narrow, dark brown sutural stripe and, in some specimens, dark brown lateral stripe; femora partially or entirely yellow or pale brown; aedeagus either weakly curved or strongly bisinuate in lateral view ........................ 7
7. Metasternum yellow; aedeagus evenly arcuate in lateral view, narrow in distal half in dorsal view (Fig. 3f); habitus as in Fig. 2h ........... .................... Triarius texanus Clark and Anderson, new species
7´. Metasternum black; aedeagus strongly sinuate in lateral view, distinctly broadened towards apex in dorsal view (Fig. 3g); habitus as in Fig. 2i ........................... .................. Triarius novoleonis Clark and Anderson, new species
description: Published as part of Clark, Shawn M. & Anderson, E. Russell, 2019, A Review Of Triarius Jacoby, 1887 (Coleoptera: Chrysomelidae: Galerucinae: Luperini), With Descriptions Of A New Genus And Four New Species, pp. 343-357 in The Coleopterists Bulletin 73 (2) on pages 349-350, DOI: 10.1649/0010-065X-73.2.343, http://zenodo.org/record/3445861