Genus Tetragonoschema Thomson, 1857

Tetragonoschema Thomson, 1857: 115 (neuter).

Type species: Tetragonoschema chrysomelinum Thomson, 1857 (by monotypy; currently T. quadratum (Buquet, 1841)) .

Tetragonoschema: Gemminger & Harold, 1869: 1386 (catalogue); Saunders, 1871: 56 (catalogue); Waterhouse, 1882: 17 (new species); Kerremans, 1892: 129 (catalogue); 1893: 110 (taxonomy); 1897: 15 (new species); 1899: 332 (new species); 1900: 297: (new species); 1903: 168 (taxonomy, key); Bruch, 1911: 231 (catalogue); Obenberger, 1915: 83 (new species); 1922: 68 (revision, key); 1923: 25 (key); 1924: 70 (new taxa); Fisher, 1925: 175 (taxonomy, key); Théry, 1926: 161 (morphology); Obenberger, 1928a: 104 (morphology); 1928b: 38 (morphology); 1930: 558 (catalogue); Théry, 1930: 46 (comment on synonymy); Hoscheck, 1931a: 163 (new species); 1931b: 742 (new species); Obenberger, 1932: 145 (new taxa); Théry, 1934: 13 (new species, taxonomy); Blackwelder 1944: 315 (checklist); Théry, 1944: 5 (revision); Obenberger, 1947: 6 (new species, notes); Cobos, 1949: 9 (taxonomy, new species); 1958: 87 (synonymy, notes on phylogeny); 1959: 11 (new species); 1972: 339 (new species); Hespenheide, 1975: 781 (mimicry); Bellamy, 1985: 421 (higher taxonomy); Cobos, 1986: 13, 21 (morphological notes); Hołyński, 1988: 51 (taxonomy); Bellamy, 1991: 21 (new species); Hołyński, 1993: 14 (taxonomy); Bílý, 2000: 111 (taxonomy); Bellamy, 2003: 68 (taxonomy, higher classification); 2005: 309 (emendation); 2008: 1517 (catalogue).

Pachypyga Steinheil, 1874: 564 (feminine).

Type species: Pachypyga undata Steinheil, 1874 (by monotypy).

Pachypyga: Kerremans, 1885: 137 (note); 1892: 115 (catalogue); 1893: 111 (taxonomy); 1903: 168 (syn. of Tetragonoschema); Fisher, 1925: 175 (taxonomy, as syn. of Tetragonoschema); Obenberger, 1930: 558 (catalogue, as syn. of Tetragonoschema); Bellamy, 1985: 421 (taxonomy, as syn. of Tetragonoschema); 2003: 68 (taxonomy, as syn. of Tetragonoschema); 2008: 1517 (catalogue, as syn. of Tetragonoschema).

Diagnosis of the genus. Small to medium-sized (2.0– 5.5 mm), more or less lustrous, black, bronze, blue, violet or bicolorous (black with red pattern) species; dorsal surface usually asetose, elytra exceptionally with short, sparse, white setae at posterior half of elytra (subgen. Tetragonoschema) or entire dorsal surface with fine, white pubescence (subgen. Patagoschema subgen. nov.); ventral surface with very indistinct, sparse, fine, white pubescence; laterosternites and transverse, preapical depression of anal ventrite often with white tomentum; frons asetose or with white pubescence, flat, convex or grooved; vertex 1.5–3.0 times as wide as width of eye; pronotum 1.8–2.5 times as wide as long with shallow, sometimes nearly indistinct lateroposterior depressions; lateral pronotal carina shortened, only exceptionally reaching pronotal midlength, sometimes completely missing; posterior pronotal angles sometimes with prehumeral keels (Fig. 61); pronotal sculpture consisting of small, well-developed and well-delineated, polygonal cells with or without tiny central granules; scutellum triangular, 1.5–2.0 times as long as wide; elytra conspicuously shortened, 1.1–1.4 times as long as wide, sometimes nearly as wide as long, flattened with deep, wide impressions; each elytron apically widely, obtusely rounded, sometimes nearly truncate; elytral epipleura well-developed reaching or nearly reaching elytral suture, sometimes distinctly visible from above (Fig. 60); elytral sculpture consisting of basal microsculpture and fine, polygonal cells without central granules; elytra without mirror-effect along suture; entire pygidium and anal ventrite completely visible from above; anal ventrite strongly modified due to shortened abdomen, situated nearly vertically with wide, deep transverse impression usually filled with white or cream-white tomentum; this impression is usually triangularly enlarged at middle (Fig. 63); form of anal ventrite rather uniform in all species; aedeagus spindle-shaped, spatulate or with lateral spines at distal half of parameres; median lobe sharply pointed apically, not serrate laterally.

The genus Tetragonoschema is closely related to the genus Anilaroides as mentioned above. The principal distinguishing characters are mentioned in the key and in the diagnosis of the genus Anilaroides (see above).

Adult morphology of the genus was summarised by Théry (1944), and Cobos (1958) briefly discussed the Gondwanian origin of the genus. Papers by Théry (1926) and Obenberger (1928a, 1928b) deal with the morphology of wings.

Bionomy. According to Théry (1944) and according to the experiences of many collectors as well as my own field observation adult beetles are flower-visitors prefering yellow and orange flowers. Flowers of the genus Opuntia (Cactaceae) are very attractive although in the Paraguayan Chaco we found some specimens also on small, blue and pink flowers. During our collecting trip to Paraguay (2010) we used yellow, orange, violet and blue dishes as traps. The most effective were yellow and orange traps. The violet and blue traps were almost non attractive.

Most of specimens of Tetragonoschema (Patagoschema subgen. nov.) cobosi sp.nov. were collected on flowers of Jarilla sp. ( Caricaceae).

Some species possess conspicuous, red and black elytral pattern imitating some species of Chrysomelidae (Clytrinae—Fig. 54) which could be some kind of mimetism or aposematic colouration (Hespenheide, 1975, 1996).

Nothing is known of the larval morphology and bionomy. It seems that the majority of species from dry biotopes develop in Acacia spp. and Prosopis spp. ( Fabaceae). In December 2010 (Paraguay, Prov. Boquéron, Loma Plata) I found larval galleries with old, dead beeetles ( T. nanum) under the bark of dead branches of Acacia praecox Hook & Arm. (Fabaceae) .

Distribution. From central Mexico to Patagonia.

Key to the species of the genus Tetragonoschema

1 Dark bronze, subcylindrical species, elytra completely or partly red-bronze; elytra convex, without lateral and preapical depressions only with flat, medial, triangular depression at anterior elytral third; elytral epipleura narrow, not reaching elytral apex (Fig. 58); frons convex with weak postclypeal depression; pronotum regularly, rather strongly convex, sometimes with two small, weakly developed, rounded depressions; antennae and tarsi reddish-brown; aedeagus short, spindle-shaped (Figs. 72–74) [subgen. Patagoschema subgen. nov.]............................................................... 2

– Black, bronze or multicolorous, shortened (sometimes nearly as wide as long) species; elytra usually very short, flat, conspicuously uneven with one common, medial depression and with deep lateral and preapical depressions; elytral epipleura wide, well-developed, reaching or nearly reaching elytral suture (Figs. 59, 60); frons usually deeply impressed with projecting prominences above antennal insertions, rarely frons convex; pronotum less convex, transverse, usually with more or less distinct lateroposterior depressions; antennae and tarsi black; aedeagus spindle-shaped or elongate, parameres very often with lateral hooks or spines (Figs. 68–69, 75–78) [subgen. Tetragonoschema s.str.]........................................... 4

2 Larger (3.8–4.6 mm), more robust species; elytra dark bronze with a red-bronze lateroposterior part (Figs. 3, 4); frons strongly convex; aedeagus short, broad, spindle-shaped (Figs. 72, 73)................................................... 3

– Small (2.2–3.7 mm), less robust; entire elytra red-bronze; frons moderately convex; pronotum rather strongly enlarged at anterior third, with two small, shallow, rounded impressions on disc; aedeagus relatively longer (Fig. 74); 2.0– 3.7 mm; Argentina (San Juan, San Luis)........................................................... T. (P.) cobosi sp. nov. (Fig. 42)

3 Pronotum slightly angulately widening from base, weakly concave at anterior third, maximum pronotal width at midlength; frontal pubescence distinct, erect, setae as long as diameter of frontal punctures; lateroposterior portion of elytra purplebronze; aedeagus—Fig. 72; 4.6 mm; S Argentina (Santa Cruz)................... T. (P.) patagonicum Obenberger (Fig. 3)

– Pronotum regularly rounded laterally, maximum pronotal width at anterior third; frontal pubescence very short, nearly indistinct, setae much shorter than diameter of frontal punctures; lateroposterior portion of elytra red-bronze; aedeagus—Fig. 73; 3.5–4.0 mm; Argentina (Neuquén).................................................. T. (P.) torresi Cobos (Fig. 4)

4 Elytral epipleura wide, reaching elytral suture, nearly entire; epipleura easily visible from above (Fig. 60); parameres always with lateral, preapical spines (Figs. 75–77).................................................................. 5

– Elytral epipleura wide but not reaching elytral suture, not visible from above (Fig. 59); parameres simple or with lateral, preapical spines....................................................................................... 7

5 Body tricoloured: head and pronotum black, elytra black with blue or violet tinge, entirely widely margined with red; aedeagus very short, stout (Fig. 75); 5.2–5.5 mm; Argentina ............................ T. (T.) rubromarginatum Théry (Fig. 51)

– Entire body bronze or black-bronze....................................................................... 6

6 Body black with feeble bronze lustre; frons deeply grooved, frontal pubescence short, sparse, nearly indistinct; pronotum asetose, moderately convex often with two small, rounded discal impressions; pronotum laterally slightly angulate just anterior of the midlength, posterior pronotal angles with a sharp prehumeral keel (Fig. 61) aedeagus long, parameres enlarged at basal third (Fig. 76); 3.6–5.2 mm; Paraguay ............................................ T. (T.) barriesi sp. nov. (Fig. 44)

– Body bronze; frons nearly flat, only weakly grooved medially, white frontal pubescence dense, long (setae as long as diameter of a frontal puncture); pronotum strongly, regularly convex, with distinct white pubescence on lateral sides; pronotum laterally regularly rounded, maximum pronotal width at anterior third; pronotum without prehumeral keels (Fig. 62); aedeagus short, rather stout, (Fig. 77); 4.5–5.5 mm; Argentina .............................. T. (T.) strandi Obenberger (Fig. 52)

7 Elytra short, more or less as long as wide, only 1.10–1.30 times as long as wide.................................... 8

– Elytra longer, much longer than wide, 1.35–1.40 times as long as wide.......................................... 15

8 Elytra bicolorous: black with green, blue or violet tinge, humeral area with red or purple patches or entire elytra margined with red................................................................................................. 9

– Entire body bronze, dark bronze or black with blue or violet tinge.............................................. 12

9 Body slightly elongate, elytra 1.30 times as long as wide; humeral and lateral parts of elytra dark red, and sometimes also apex of elytra red; aedeagus rather long, parameres with preapical spines (Fig. 78); 3.3–3.8 mm; Argentina, Bolivia, Brazil, Paraguay ............................................................ T. (T.) cupreocingulatum Hoscheck (Fig. 45)

– More robust species; elytra 1.10–1.20 times as long as wide; humeral area of elytra red or purple, sometimes also entire lateral and posterior margins red; aedeagus more or less spindle-shaped, parameres without preapical spines................ 10

10 Less robust species, elytra 1.10 times as long as wide; ventral surface black with golden tinge; anterior pronotal margin angulate medially; male metatibiae slightly curved, enlarged towards apex; aedeagus—Fig. 79; 3.1–3.5 mm; Brazil (Goyas)............................................................................. T. (T.) fossicolle Kerremans (Fig. 47)

– Larger, elytra 1.20 times as long as wide; ventral surface black or black with very slight green tinge; anterior pronotal margin moderately rounded medially; male metatibiae straight, not enlarged apically..................................... 11

11 Only humeral area of elytra red or purple; pronotum and remainder of elytra black with green tinge, exceptionally (in some females) blue with green tinge; pronotum laterally more rounded; frontal depression shallower; aedeagus—Fig. 80; 3.2–5.3 mm; Belize, Costa Rica, Honduras, Mexico, Nicaragua .......................... T. (T.) humerale Waterhouse (Fig. 48)

– Humeral and apical parts (exceptionally also entire lateral margin) red or purple; pronotum and remainder of elytra black with geen-bronze tinge; sometimes elytra with a narrow, golden-red sutural stripe; rarely red pattern missing and entire dorsal surface black or black with blue-green tinge; prontum laterally more or less angulate; frontal depression deeper; aedeagus—Fig. 81; 3.2–5.2 mm; French Guyana, Tobago, Trinidad, Venezuela ................. T. (T.) trinidadense Bellamy (Fig. 55–57)

12 Entire body bronze, often with red tinge, dorsal surface sometimes with blue tinge; frons with very short, white pubescence; posterior pronotal angles with prehumeral keel (like Fig. 61); parameres with large, preapical spines (Figs. 68, 69)....... 13

– Entire body black, or black with a rather intense violet lustre; frons asetose; pronotum without prehumeral keel (like Fig. 62); aedeagus long, slender, parameres without preapical spines (Figs. 70, 71)........................................ 14

13 Body stout, elytra 1.10–1.20 times longer than wide; pronotum subparallel in posterior half; elytra slightly narrowed posteriorly; male bronze, female bronze with blue tinge on entire dorsal surface; aedeagus robust, relatively short, parameres with large preapical spines (Fig. 68); 3.4–4.8 mm; Brazil (Surumu) T. (T.) alvarengai Cobos (Fig. 9)

– Body smaller and more slender, elytra 1.30 times as long as wide; pronotum strongly narrowing in posterior half; elytra subparallel; entire body bronze, head and posterior elytral margin with slight red lustre; aedeagus slender, parameres with small preapical spines (Fig. 69); 3.4–3.8 mm; Colombia, Venezuela ......................... T. (T.) darlingtoni Théry (Fig. 46)

14 Body black with intense violet lustre; elytra subparallel, nearly as wide as long, 1.10 times as long as wide; elytral apex transversely truncate; male metatibiae slightly curved inwards; sculpture of pronotal disc regular, very fine, almost indistinct in front of scutellum; pronotum rounded laterally, maximum pronotal width at posterior third; aedeagus nearly spindle-shaped, parameres enlarged at basal third (Fig. 70); 4.3 mm; Haiti ......................... T. (T.) quadratum (Buquet) (Fig. 24)

– Body black sometimes with very slight red tinge; lateral margins of elytra weakly emarginate; elytra 1.15–1.20 times as long as wide; elytral apex obliquely truncate; male metatibiae straight; sculpture of pronotal disc rougher, quite distinct, somewhat transverse in front of scutellum; pronotum laterally obtusely angulate, maximum pronotal width at midlength; aedeagus slender, subparallel (Fig. 71); 4.2–4.5 mm; Argentina, Brazil, Paraguay ............. T. (T.) purpurascens Kerremans (Fig. 50)

15 Black-bronze, matt with silky lustre; frons asetose, deeply grooved, supra-antennal prominences strongly projecting; pronotum cordiform with two small, rounded discal impressions; lateroposterior pronotal depressions weak, nearly indistinct, pronotal punctures very fine with tiny central granules; aedeagus spindle-shaped, parameres with very small preapical spines (Fig. 64); 3.9–4.8 mm; Argentina, Brazil, Paraguay ...................................... T. (T.) aeneum Kerremans (Fig. 43)

– Bronze, rather shiny species; frons with white pubescence, only slightly grooved or convex, supra-antennal prominences very small; pronotum not cordiform, only rarely with two small, rounded discal impressions; lateroposterior pronotal depressions well-developed, pronotal punctures coarse, without central granules; aedeagus broadly spindle-shaped or elongate, without lateral spines (Figs. 65, 66)............................................................................. 16

16 Less robust, dark bronze, rarely blue; frons convex, frontal pubescence short (as long as diameter of a puncture); apex of each elytron broadly rounded (Fig. 49); aedeagus broadly spindle-shaped (Fig. 65); 3.0– 4.6 mm; Argentina, Bolivia, Brazil, Paraguay .................................................................... T. (T.) nanum Obenberger (Fig. 49)

– More robust, bronze, rarely black-blue; frons slightly grooved, frontal pubescence long (much longer than diameter of a puncture); each elytron obliquely angled to the rounded apices, maximum elytral length at suture (Fig. 53) aedeagus elongate, parameres enlarged at basal half (Fig. 66); 2.7–5.0 mm; Argentina ................. T. (T.) undatum (Steinheil) (Fig. 53)