Monilonotum Bartlett & Lambkin 2022, gen. nov.

Monilonotum gen. nov.

ZooBank registration: urn:lsid:zoobank.org:act: 36F952E9-96BE-41C9-BC6F-294E1E13FA00

Gender. Neuter.

Type species. Opilo pascoii Gorham, 1876, by present designation.

Diagnosis. Intrafoveal setae, if present, minute and not clearly visible under magnification (or apparently absent) (Fig. 22); basitarsi without a distinct ventral pad; ninth elytral stria present; inside lateral rims of elytral punctures without nodules; elytral interstriae setae arranged in simple rows; elytral striae terminating abruptly near mid-length; pronotal basal collar typically paler than pronotal disc; carinae of inside face of antennal scape often not well-defined; median lobe without rearward-directed spine or barb, distally digitiform.

Description. Eyes facets intermediately coarse, strongly emarginate above supra-antennal elevations, separated by 0.88–1.62 eye widths; carinae of rear face of antennal scape short or weak (less conspicuous than most other genera treated here); sensory face of terminal maxillary palpomere 1.6 longer than inside margin; sensory face of terminal labial palpomere 1.0–2.5 times longer than inside margin; genae wrinkled, submentum smooth; pronotum 1.5–3.0 times longer than wide, middle slightly broader than pronotal arch, smooth, almost impunctate, median sulcus subtle or apparently absent, basal collar typically paler than disc; elytra 2.52–2.95 times longer than wide at humeri, punctures without nodules, eighth stria beginning immediately behind humeral tumescence, all stria terminating abruptly near elytral mid-length, interstrial setae in single rows, intrafoveal setae apparently absent in majority of punctures (an extremely short seta, difficult to observe even under high magnification, was occasionally found in some specimens); hindwing with CuA 3+4 and CuA 1 crossveins complete, MP 3+4 substantialy extended basad of CuA 1 crossvein; tarsi each with three well-developed ventral pads; tegmen ventral sinus half to two-thirds as long as dorsal sinus; median lobe without apico-lateral spine, with distal digitiform process; specular fork Y-shaped.

Etymology. The generic epithet Monilonotum (from Latin ‘monile’ meaning necklace, and Latin ‘nota’ meaning mark and also suggestive of the pronotum), refers to the paleness of the pronotal collar which, in the majority of species of this genus, is characteristically contrasted against a darker pronotum.

Remarks. Evidence for early divergence of Monilonotum from the other genera treated here can be found in the digitiform terminal process of the median lobe of Monilonotum which resembles that found in genera of Australian Opilonina such as Trogodendron Spinola and Olesterus Spinola, the extreme reduction of intrafoveal setae (putatively synapomorphic), the loss of the carina of the antennal scape (also putatively synapomorphic), plus the retention of plesiomorphic fused/non-separated state of the spicular fork (collectively more derived in the remaining genera of this revision).

Key to species of Monilonotum

1 Pale transverse elytral fascia, if present, flat, not calositous or bullose (Figs 151–154).......... (pascoei species group) ... 2

- Pale transverse elytral fascia always present as a raised, calositous or bullose formation (Fig. 155).................................................................................................. (rufiventre species group) ... 5

2 (1) Elytral colouration yellowish to pale brown and dark brown (Fig. 151).................. Monilonotum bunyense sp. nov.

- Elytral colouration black, reddish-brown and white.......................................................... 3

3 (2) Each elytron with a small white fleck between transverse fascia and base; elytral apices without maculation (Fig. 152)............................................................. Monilonotum doddi (Schenkling) stat. rev., comb. nov.

- Elytra between fascia and base without white fleck; elytral apices with whitish macula.............................. 4

4 (3) Metacoxae and metaventrite of similar colour; interstices anterior to elytral fascia thin and slightly raised, giving punctation a grid-like appearance within this area............................................ Monilonotum sundholmi sp. nov.

- Metacoxae whitish or yellowish, metaventrite orange-brown; interstices anterior to elytral fascia smooth, punctation not gridlike in appearance within this area.................................... Monilonotum pascoei (Gorham) comb. nov.

5 (4) Elytral base red, sternum not red............................... * Monilonotum eburneocincta (Gorham) comb. nov.

- Elytra entirely black; sternum orange............................. * Monilonotum rufiventre (Gerstmeier) comb. nov.

* See notes below, under each species heading, for information about potentially superficially similar undescribed species.