Omma Newman, 1839

Escalona, Hermes E., Lawrence, John F. & Ślipiński, Adam, 2020, The extant species of the genus Omma Newman and description of Beutelius gen. nov. (Coleoptera: Archostemata: Ommatidae: Ommatinae), Zootaxa 4728 (4), pp. 547-574 : 549-551

Omma Newman, 1839

( Figs 1–3 , 14–18, 21 , 39–43 , 51–55 , 58–60, 63 , 64–66 , 69–70 , 74 , 76–78, 80–81 , 90 )

Omma Newman 1839: 303 . Type species: Omma stanleyi Newman, 1839 , by monotypy.

Procarabus Oppenheim 1888: 236 . Type species: Procarabus zitelli Oppenheim, 1888 . Ponomarenko 1971 (synonymy).

Ommamima Ponomarenko 1964: 50 . Type species: Ommamima pilosum Ponomarenko, 1964 . Ponomarenko 1969 (synonymy).

Diagnosis. Body elongate, moderately flattened, often tuberculate, clothed with moderately short and decumbent setae ( Fig. 2 ). Head slightly elongate, usually abruptly narrowed behind eyes, with distinct neck region ( Fig. 14 ). Posterior tentorial pits clearly indicated ( Fig. 15 ). Anterior third of gulamentum not depressed ( Fig. 15 ). Antennae filiform ( Fig. 2 ) and setose. Ligula truncate, apical labial and maxillary palpomeres expanded and securiform, when extended posteriorly not or just reaching the level of the eyes ( Fig. 15 ). Prothorax slightly longer than wide, without lateral pronotal carinae; notopleural suture complete to anterior edge, sternopleural suture absent ( Fig. 42 ). Prosternal process incomplete and short ( Fig. 40 ). Elytra with mesal edge of sutural flange finely denticulate ( Fig. 69 ); epipleura complete and moderately broad (variable in fossil species). Outer surface of protibia in male with setose tubercle at basal third or fourth ( Fig. 81 ; fig. 9 in Lawrence 1999).

Description. Length: 6–26 mm, 2.4–3.0 times as long as wide, slightly flattened dorsally and distinctly so ventrally, with sides of pronotum rounded and elytra apex independently rounded. Colour uniformly dark brown to black; upper surfaces tuberculate, tubercles clothed with short, slightly thickened, decumbent setae; last abdominal ventrite in males often with longer and denser setae.

Head prognathous, longer than wide, constricted posteriorly to form a neck, temples and median occipital endocarina present. Eyes entire and very finely facetted, without interfacetal setae. Antennal insertions lateral, barely concealed by frontal ridges; subantennal grooves absent. Frontoclypeal suture absent. Labrum transverse, apically convex, fused to clypeus. Antenna short, not extending beyond base of prothorax, 11-segmented and filiform, with glabrous areas at the sides of antennomeres 6–11 probably containing sensory organs. Mandible tridentate with vertically aligned teeth, without mola or prostheca; its dorsal surface near base with setose cavity (figs 6–7 in Grebennikov & Leschen 2010). Maxilla highly reduced and partly concealed by mentum; cardo and stipes sclerotised; galea and lacinia slender, hyaline and setose, the latter without uncus. Apical maxillary palpomere expanded and securiform, with small cavity bearing sensilla near outer edge of upper surface ( Fig. 20 ; figs 4, 5 in Lawrence 1999). Mentum about as long as wide with deep basal pit; small, truncate ligula and palpal insertions concealed by mentum in ventral view; apical labial palpomere expanded and securiform, with a cavity like that on the apical maxillary palpomere. Maxillary and labial palps, when extended posteriorly, not reaching the level of the eyes ( Fig. 15 ). Posterior tentorial pits clearly indicated ( Figs 15, 21 ). Gular sutures well separated and extending to the submental peduncle ( Fig. 21 ); gula longer than wide. Gulamentum anteriorly barely convex ( Fig. 16 ). Corpotentorium weakly developed or absent. Cervical sclerites absent.

Prothorax distinctly narrower than the distance across elytral humeri, widest anteriorly with sides slightly sinuate; lateral pronotal carinae absent. Pronotum disc convex with lateral paired anterior and posterior deep impressions. Prosternum in front of coxae moderately long, pleurosternal suture absent, without paired crural impressions. Prosternal process incomplete and short, slightly extended between procoxae, narrowed apically and acute at apex. Notopleural suture complete to anterior edge, never joined by pleurosternal suture. Procoxae subglobular, not strongly projecting, without concealed lateral extensions, with reduced coxal plates; trochantin large, well sclerotised, broadly exposed and abutting sternum and propleural cavity. Procoxal cavities slightly transverse, contiguous, broadly open externally and internally. Promesothoracic interlocking mechanism formed by mesanepisternal con- dyle ( Fig. 52 ) and propleural cavity. Scutellar shield distinctly elevated from the anterior portion of the mesoscutellum, not elevated above elytra, constricted at base and broadly curved and crenulate posteriorly ( Fig. 43 ). Elytra complete with independently rounded to acute apices and ten rows of transversely oval window punctures; epipleura moderately broad (variable in fossil species) and complete. Mesoventrite at middle with acute anterior projection separating paired procoxal rests extending onto mesanepisterna, mesoventral cavity absent; discrimen long and transverse (mesokatepisternal) suture incomplete ( Fig. 54 ). Mesoventral process divided into two short, acute processes ( Fig. 54 ). Mesocoxae more or less globular, slightly projecting, with short plates and exposed trochantins. Mesocoxal cavities about as long as wide, contiguous, partly closed laterally by mesepimera and metanepisterna; meso- and metathoracic joint within coxal cavities membranous. Metaventrite ( Figs 51, 52, 53 ) strongly narrowed anteriorly; discrimen present; transverse (metakatepisternal) suture well developed. Metanepisternum completely exposed, widest near anterior end; exposed portion of metepimeron narrowly elongate and widest at posterior end; metatrochantins exposed. Metacoxae strongly transverse with subconical mesal projections, contiguous, extending laterally to meet elytra, with weak coxal plates. Metendosternite with a moderately long, slender stalk, short, broad ventrolateral processes, moderately long and distally slender lateral arms, and a moderately long, apically emarginate anterior process with tendons moderately widely separated on either side of emargination.

Hind wing well developed and moderately broad, with very short bending zone near apex of radial bar (anterior wing strut); pterostigma absent; two cross-veins join RA 1+2 and RA 3+4 to form brachial cell; RP complete almost to wing base, joined to RA 3+4 by four cross-veins; RP and MP joined by two cross-veins forming the oblongum cell; MP 1+2 with very short bending zone or hinge and a very short, straight medial spur; medial field with four free veins and no medial fleck; wedge cell well-developed and apically truncate; anal lobe well developed, without embayment; AP 3+4 forked.

Legs moderately long and slender; tibia subequal in length to femur; lateral surface of protibia often with a setose tubercle at basal third in males (fig. 9 in Lawrence 1999); protibial apex parallel. Tibial spurs well-developed, usually unequal and paired on all legs; protibial spurs scoop-like and widely separated, major mesotibial spur scoop-like, metatibial spurs subequal, apex pointed. Tarsi 5-5-5; tarsomeres without ventral lobes; pretarsal claws simple; empodium bisetose.

Abdomen ( Fig. 74 ) with five flattened ventrites more or less connate, separated by very narrow grooves and all on the same plane, with edges abutting; lateral edges of ventrites 1 to 4 with small bare patches; ventrite 5 with a submarginal groove, except near base, vestiture similar in males and females. Aedeagus of modified trilobate type, with parameres completely fused to phallobase and partially fused together, each with a mesal notch near apex. Ovipositor narrowly elongate, gonocoxites each with well-developed apical gonostylus.

Species included. Extant: O. stanleyi Newman, 1839 . Fossils: O. aberratum Ponomarenko 1968: 126 , Kaz- akhstan; Jurassic. O. altajense Ponomarenko 1997: 49 , Mongolia; Jurassic. O. antennatum Ponomarenko 1997: 50 , Mongolia; Cretaceous. O. avus Ponomarenko 1969: 103 , Kyrgyzstan; Jurassic. O. brevipes (Deichmüller, 1886) , Germany; Jurassic. O. daxishanense Cai & Huang 2017: 279 , China; Jurassic. O. delicatum Tan et al., 2012 , China; Jurassic. O. gobiense Ponomarenko 1997: 49 , Mongolia; Jurassic. O. jurassicum Ponomarenko 1968: 125 , Kazakh- stan; Jurassic. O. liassicum Crowson 1962 , UK; Late Triassic (type examined). O. lii Jarzembowski et al. 2017: 114 , Myanmar; Cretaceous. O. pilosum ( Ponomarenko, 1964) , Kazakhstan; Jurassic [misspelled as O. pilpsim in Tan et al. (2012) ]. O. sibiricum Ponomarenko 1966: 138 , Russia; Cretaceous. O. zitteli ( Oppenheim, 1888) .

Comments. An historical account of Omma classification is presented in Lawrence (1999). Hörnschemey- er (2009) performed a species-level morphological phylogenetic analysis of extant archostematans, recovering a monophyletic Omma (clade xxx) containing a subclade, clade xxxi: O. stanleyi + ( O. mastersi , O. sagitta and O. rutherfordi ) in all the analyses. The monophyly of Hörnschemeyer’s (2009) clade xxxi was supported by the long maxillary palps (character 30–1) and distinctive dorsal white ribbed scales on pronotum and elytra (characters 45–1 and 56–1). We found additional characters that support this major split within the genus and that led us to recognise the new genus Beutelius for the latter clade. As diagnosed here, the only extant species retained in Omma is O. stanleyi , while the remaining species are transferred to Beutelius .

The several fossil species described in Omma lack useful diagnoses, so we can assign with confidence to Omma only the amber inclusion O. lii Jarzembowski et al. and the impressions O. daxishanense Cai & Huang and O. liasicum Crowson (type examined). The placement of other Omma fossil species requires a thorough comparative study of their type material as well as that of other fossil genera of Ommatinae .

Biology. The larva of the genus remains unknown. Adults of O. stanleyi have been collected under loose Eucalyptus bark, exhibiting thanatosis (G.B. Monteith, pers. comm.).

Distribution. Omma stanleyi Newman occurs in eastern Australia from VIC, SA and NSW to central QLD.

Figures

FIGURES 1–3. Omma stanleyi: 1, Natural habitat, Queensland, Australia ©Dash Huang (17 Jan 2017); 2–3, habitus: 2, dorsal (♀ 20 mm, VIC); 3, same, ventral.

FIGURES 14–21. Omma stanleyi: 14–19. Head (♀): 14, dorsal, 15, ventral, 16, lateral, 17, frontal, 18, mandible, dorsal; 19, Beutelius rutherfordi (paratype ♂): labial palp; 20, B. mastersi (♀): maxilla; 21, O. stanleyi: head, latero-ventral.

FIGURES 39–44. Omma stanleyi (♀): 39–43. 39, pronotum, 40, prothorax, ventral, 41–42, prothorax, lateral, 43, scutellum; 44, Beutelius rutherfordi, prothorax, lateral (paratype ♂).

FIGURES 51–55. Omma stanleyi (♀): 51, pterothorax, ventral; 52, pterothorax, latero-ventral; 53, pterothorax and hind legs; 54, bifid mesoventral process; 55, abdominal ventrites 1 and 2 (in part).

FIGURES 56–63. Beutelius sagitta (♂): 56, epipleuron, ventral view; B. rutherfordi (♂): 57, epipleuron, ventral view; O. stanleyi (♀) elytron: 58–60, 63. 58, ventral view with epipleuron, 59, dorsal, 60, internal, 63 dorsal; B. mastersi (♀) elytron: 61–62. 61, dorsal, 62, ventral view with epipleuron.

FIGURES 64–66. Omma stanleyi (♀) wing: 64, complete view; 65, wing base (in folded wing); 66, wing, apical field, with apical wing folding. Veinal nomenclature abbreviations: BR: radial basivenale. BM: redial basivenale. BCu: cubital basivenale. AA: anal anterior. AP: anal posterior. Cu: cubitus. C: costa. ScA: subcosta anterior. ScP: subcosta posterior. RA: radius anterior. RP: radius posterior. MP: media posterior. WC: wedge cell. BC: brachial cell. Cross-veins: rp-mp, r, cv1: mp3+4-cua, cv2: mp1+2-mp3+4, cv3: mp1+2-mp3.

FIGURES 67–70. Beutelius mastersi (♂): 67, wing (veinal nomenclature as in Fig. 64); B. sagitta (♂): 68, wing; Omma stanleyi: 69–70. 69, elytron base, 70, elytron, close detail of sutural flange.

FIGURES 71–75. Omma stanleyi and Beutelius spp. abdominal ventrites and tergites: 71, B. rutherfordi (♂, holotype); 72, B. mastersi (♀) ventrites; 73, B. sagitta (♂) ventrites; 74, O. stanleyi (♀) ventrites; 75, B. sagitta (♂), tergites.

FIGURES 76–84. Omma stanleyi (♀): 76–78. 76, foreleg, 77, midleg, 78, hind leg. Forelegs (♂): 79–84. 79, Beutelius rutherfordi; 80–81, O. stanleyi, 80, anterior view, 81, lateral view; 82–83, B. sagitta, 82, anterior view, 83, posterior view; 84, B. mastersi, anterior view.

FIGURES 85–95. Beutelius spp., mentum: 85–86. 85, B. mastersi, 86, B. rutherfordi (paratype ♂); 87, B. mastersi, mesonotum; 88, B. mastersi, pterothorax, ventral; 89, B. rutherfordi, pterothorax, ventral; aedeagus: 90–95. 90, Omma stanleyi; 91–92, B. mastersi; 93, B. reidi sp. nov.; 94, B. rutherfordi; 95, B. sagitta.