Zenascus, Grzymala & Leschen, 2020

Grzymala, Traci L. & Leschen, Richard A. B., 2020, Sexual Dimorphism of New Zealand Puppet Beetles (Aderidae, Coleoptera, Tenebrionoidea): Systematic Revision, Description of Three New Genera, and Phylogeny for Zenascus, gen. n., Zootaxa 4889 (1), pp. 1-59 : 27-29

Zenascus gen. n.

Type species: Zenascus obscurus ( Broun, 1893) , here designated.

Etymology. This genus is named with reference to New Zealand where the first species observed to comprise this lineage were examined, disarticulated, and described.

Diagnosis. This genus is distinguished from other New Zealand genera by the specific primary punctation pattern of the metaventrite ( Fig. 13F ) consisting of relatively deep slit-like punctures, the shallow integument excavation along the length of the femur with modified setae overlying this excavation (reduced in some taxa), and the expansion of the metatibial apex with the accompanying tuft of thickened setae in a triangular shape ( Fig. 13E ). Zenascus can also be distinguished from other genera by the shape of the pronotum ( Fig. 13C ), though is superficially very similar to Pseudozena but can be distinguished by antennomere 3 much shorter and smaller in comparison to antennomere 4 and the distinct modifications to the metafemora. Another distinguishing characteristic of this is genus is the males tend to have their more terminal antennomeres modified and form what we refer to in the key as a club.

Description. Small to average size for family, length 1.36–2.11 mm. Body about 1.8–2.5× longer than wide. Dorsal surface piceus to testaceous, testaceous antennae, mouthparts, and legs; vestiture uniseriate or biseriate, clothed with thin, decumbent pubescence arising anterad of each puncture, between 1–4× length of puncture, without additional pubescence or with 4–5 additional thin, slightly shorter, decumbent setae between each puncture pair. Ventral vestiture biseriate. Head abruptly constricted posteriorly, forming a neck concealed within pronotum. Eyes moderately protuberant, coarsely faceted, with moderate anterior emargination, with short interfacetal setae. Frontoclypeal suture present. Antennal insertions anterad of eyes and eye emargination, produced on slight ridge. Antennae with scape slightly longer than wide, dorso-ventrally flattened and expanded in some species; pedicel subglobular, apex wider than base of antennomere 3; antennomere 3 shorter and thinner than pedicel (except Z. antennalis ); antennomere 4 longer or subequal to antennomere 5; antennomeres 5 and 6 subequal in length and width; antennomeres 7–9 subequal in width and decreasing slightly in length or highly modified; antennomere 10 subquadrate, length subequal to width; antennomere 11 elongate, 2× longer than antennomere 10; antennomeres 3–11 covered in moderately dense, suberect pubescence, with or without additional pilosity covering antennomeres 7–9. Mandible bidentate. Apical maxillary palpomere greatly expanded from base to apex. Apical labial palpomere expanded. Pronotum subquadrate, length subequal or slightly greater than width, sides slightly rounded to sinuate, anterior angles rounded, posterior angles rounded; basal margin wider than apical margin; disc with two distinct, deep, circular punctures present antero-laterally to basal margin. Prosternal process short, extremely narrowed posteriorly, apex acute. Mesonotum with slight anterior notch; suture between mesonotum and scutellar shield distinct, straight; scutellar shield broad, posteriorly truncate with edges acute and a row of deep punctures confined to basal margin. Elytral length 1.4–2.1× elytral width and 3.3–4.2× pronotal length; with slight to moderate obliquely impressed subscutellar depression. Elytron with elongate elliptical punctures; apices rounded, without protrusions. Mesoventrite without procoxal rests. Mesanepisternum with deep, elongate punctation. Mesepimeron without distinctive deep, punctation. Mesanepisternal-mesepimeral suture faintly indicated. Mesoventral process complex, moderately broad about 0.5x width of mesocoxa posterior margin inserted below metaventral process. Metaventrite with deep punctures, approximately evenly spaced across surface except medially and at margins anterad of metacoxae; discrimen distinct, long, without invagination. Metendosternite with long lateral arms; anterior process absent; laminae absent. Proleg with femur simple, width subequal basally, medially and apically; tibia curved strongly inward at base, width slightly expanded from base to apex, tibial spurs absent, with numerous thickened setae on ventro-lateral surface, confined to apical half; tarsi with tarsomeres 1–3 subequal in width; tarsomeres 1 and 2 with slight ventral expansion; tarsomere 3 with ventral expansion 3× greater in length than dorsal edge; tarsomere 4 reduced in length and width; tarsomere 5 elongate. Midleg with coxal ventro-lateral face having four thickened setae; femur width slightly expanded from base to apex; tibia width slightly expanded from base to apex, length 11–13× width just distad of base; tarsomeres 1–3 subequal in width; tarsomere 3 expanded ventrally, ventral surface with tactile setae; length of 1 st mesotarsomere 5–6× greater than mesotarsomere 2; tarsomere 1 with ventral row of suberect thickened setae. Hind leg with coxa lackingt deep, elongate punctures along apical margin; tibia gradually expanding in width from base to apex, apex broader than base of tarsomere 1; tarsomeres 1 and 2 subequal in width; tarsomere 1 longer than 2; tarsomere 3 reduced in length and width; tarsomere 4 elongate. Abdominal ventrites 1 and 2 connate, suture only indicated by absence of deep, elongate punctures followed by distinctive row of punctures; abdominal process moderately acute; length and width of ventrites 3 and 4 subequal; deep punctures, sparse and irregularly spaced on ventrites 1–3, smaller, shallower punctures present on ventrites 4 and 5; ventrite 4 without an elevated plate; ventrite 5 with or without an excavation. Phallobase posteriorly rounded; apicale with or without accessory lobes; penis with anterior struts present, length variable.

Females. Ventrite 5 without setose pit. Apex of last abdominal ventrite and tergite without serration.

Distribution. New Zealand, Australia, New Caledonia, and Papua New Guinea.

Remarks. Zenascus is presently restricted to Australasia and is recovered as a monophyletic group in a preliminary molecular phylogeny ( Grzymala 2016). Zenascus does not key well in the classification of Werner (1990) because the accessory lobes on the apicale are present or absent dependent on the species and the metafemoral setal brushes are lacking in both sexes, though males and females of all species have a characteristic excavation of the integument with overlying thickened setae ( Figs 20 A–20J). We have observed specimens from Papua New Guinea with the elytral pubescence arranged into a color pattern as has been observed for other aderid genera such as Ganascus Casey from North America and Mixaderus Collado & Alonso-Zarazaga from Africa (T. Grzymala, per. obs.). Extreme modifications of the male antennomeres ( Figs 14 H–J, 15A–15C) have only been observed for some of the New Zealand species we place in Z enascus.

Key to Species of Zenascus

1. Elytra with uniseriate vestiture, without additional setae between pairs of single seta arising anterior of each puncture; integument black.......................................................................................... 2

- Elytra with biseriate vestiture, with additional setae between pairs of primary setae arising anterior to each puncture; integument dark brown or testaceous........................................................................... 4

2. Antennomeres 8–11 brunneous or piceus; males with antennomeres 7–9 modified ( Fig. 14F ); North Island; Fig. 12A..................................................................................... Z . antennalis ( Broun, 1893)

- Antennomeres 8–11 testaceous; males with antennomeres 7–9 unmodified ( Figs 14D & 14E )......................... 3

3. Metatibiae gradually expanded from base to apex ( Figs 17A & 17B ); scape testaceous (occasionally with base brunneous or piceous); males without medial impression on apical abdominal sternite; North Island and Three Kings Island; Fig. 11D..................................................................................... Z . nitidus ( Broun, 1893)

- Metatibiae abruptly expanded from midlength to apex ( Figs 17C & 17D ); scape brunneous or piceous; males with medial impression on apical abdominal sternite; North Island; Fig. 11E....................................... Z . elenae, sp. n.

4. Elytra distinctly bicolored ( Figs 11A,C ).................................................................. 10

- Elytra generally unicolorus or infuscate, but lacking distinct maculae............................................ 5

5. Antennal club of male present and highly modified ( Figs 14 G–J); antennomeres 9 and 10 of female weakly to strongly transverse ( Figs 14 G–J).................................................................................... 6

- Antenna of male not highly modified and filiform ( Fig 14B ); antennomeres 9 and 10 not weakly to strongly transverse ( Fig 14B ); North Island and South Island; Fig. 11B.......................................... Z . obscurus ( Broun, 1893)

6. Pronotal punctation coarse ( Figs 12B,C )................................................................... 7

- Pronotal punctation absent to fine, and not coarse ( Figs 12D,E )................................................ 8

7. Male with antennomeres 7 and 8 modified with lateral extensions ( Figs 14H , 15A ); pronotum often with weak basal impressions with raised areas glabrous; color usually pale, golden to testaceous, rarely darker; North Island and northern region of the South Island; Fig. 12C..................................................................... Z . roberti, sp. n.

- Male with antennomeres 7 and 8 less modified, lacking lateral extensions ( Figs 12B , 14G ); pronotum often with deeply impressed basal fovea with raised areas punctate; color dark and brunneous; North Island....... Z. xenarthrus ( Broun, 1910)

8. Occiput of head in male without a distinct ridge ( Fig. 12D ); male antennomere 7 narrowed in cross-section ( Figs 14I , 15B ); North Island; Fig. 12D........................................................... Z . luniger ( Champion, 1916)

- Occiput of head in male with a distinct ridge ( Fig. 12E ); male antennomere 7 broad ( Figs 14J , 15C ); Three Kings Islands; Fig. 12E.................................................................................. Z . incensum, sp. n.

10. Elytral integument overall testaceous with medial brown patches; males without impression at metafemoral apex; Three Kings Islands, Fig. 11C......................................................................... Z . aurum, sp. n.

- Elytral integument overall brunneous with only humeral angles testaceous; males with impression present on ventral surface of metafemoral apex ( Fig. 20A ); North Island and South Island, Fig. 11A....................... Z . coloratus ( Broun, 1893)

Figures

FIGURES 11A–E. Dorsal habitus images. (A) Zenascus coloratus (Broun), male; (B) Zenascus obscurus (Broun), male; (C) Zenascus aurum, sp. n., female; (D) Zenascus nitidus (Broun), male; (E) Zenascus elenae, sp. n., male. Scale bars = 1.0 mm.

FIGURES 12A–E. Dorsal habitus images. (A) Zenascus antennalis (Broun), male; (B) Zenascus xenarthrus (Broun), male; (C) Zenascus roberti sp. n., male; (D) Zenascus luniger (Champion), male; (E) Zenascus incensum sp. n., male. Scale bars = 1.0 mm.

FIGURES 13A–H. Zenascus obscurus, scanning electron micrographs. (A) head, frontal view; (B) antenna; (C) pronotum (D) proleg; (E) metatibia; (F) metaventrite; (G) abdomen; (H) tergite VII.

FIGURES 14A–J. Antennal illustrations for Zenascus species, male on left, female on right.(A) Z. coloratus; (B) Z. obscurus; (C) Z. aurum, sp. n.; (D) Z. nitidus; (E) Z. elenae, sp. n.; (F) Z. antennalis; (G) Z. xenarthrus; (H) Z. roberti, sp. n.; (I) Z. luniger; (J) Z. incensum, sp. n. Scale bar = 0.1 mm.

FIGURES 15A–C. Scanning electron microscope images of Zenascus species with close-ups of male antennomeres 7–9. (A) Z. roberti, sp. n.; (B) Z. luniger; (C) Z. incensum, sp. n.. Scale bars = 20μm.

FIGURES 17A–D. Scanning electron microscope images, Zenascus species, metatibia (A) Z. nitidus, male; (B) Z. nitidus, female; (C) Z. elenae, sp. n., male; (D) Z. elenae, sp. n., female. Scale bars = 30μm.

FIGURES 20A–J. Scanning electron microscope images, ventral view of metafemora for Zenascus species. (A) Z. coloratus, male; (B) Z. obscurus, male; (C) Z. aurum, sp. n., male; (D) Z. nitidus, female; (E) Z. elenae, sp. n., male; (F) Z. antennalis, female; (G) Z. xenarthrus, male; (H) Z. roberti, sp. n., male; (I) Z. luniger, male; (J) Z. incensum, sp. n., male. Scale bars = 60μm.