Scaphodius drehu, Reid & Beatson, 2012

Reid, C. A. M. & Beatson, M., 2013, Chrysomelid males with enlarged mandibles: three new species and a review of occurrence in the family (Coleoptera: Chrysomelidae), Zootaxa 3619 (1), pp. 79-100 : 84-88

Scaphodius drehu sp. nov.

( Figs 7–18 )

Material examined. Holotype:3/ Loyalty Is, Ouvea , Fayaoue , 0–50m, xii.1968 / N. L. H. Krauss collector Bishop Museum/ Nyetra sp., G. A. Samuelson det. 1971/ ( BPBM); paratype: Ƥ, same data as holotype except i.1969 ( BPBM).

Description. Length: 5mm (male = female), greatest width 3mm (male), 3.5mm (female). Colour: reddishbrown, except (i) antennomeres 8–11, female mandibles, disc of pronotum and elytral humeri, distal half female tibiae, darker brown; (ii) antennomeres 1–5, labiomaxillary complex, frontoclypeus of female, legs paler brown; (iii) labrum, posterior angles pronotum (dorsal and ventral), prosternal and mesoventrite processes, anterior margin metaventrite, mesanepisternum, mesepimeron, deep yellow to orange. Dorsal pubescence: head, pronotum [except disc—rubbed off?] and elytral striae with dense recumbent silvery setae.

Head: roughly circular, broadest at genae below eyes (male) or at eyes (female); male frontoclypeus diamond shaped, convex, except reflexed anterior edge which is produced apically and bilobed; female frontoclypeus not anteriorly produced, apical margin flat, shallowly triangularly excavate; sides frontoclypeus bounded by oblique antennal grooves from antennal sockets to lateral margins buccal cavity; head densely and finely punctured (punctures separated by their diameters, about eye facet sized) and clothed in silvery recumbent setae, except antennal grooves, antennal tubercles and shallowly depressed centre of vertex impunctate and glabrous; eyes oval (female larger than male), inner margin feebly concave; interocular space 2.5x (male) or 2x (female) length of eye; gena long, minimum length 0.4–0.45x eye length; antennae much longer than width of head (male) or slightly longer than width of head (female), all segments elongate, 1–5 sparsely setose and thin, almost parallel-sided, 6–10 densely setose and triangular with apical sensory patch, 11 elongate oval (10 & 11 absent in male); antennomere 1 longest, greatly elongated, length 0.8x eye length (male) or 0.35x (female); labrum transverse with convex apex, apically swollen in male, flat in female; mandible apices normal in both sexes, with two interlocking teeth; male with massive horn arising from base of left mandible, curving across face and upwards in front of right eye; apical maxillary palpomere flattened-cylindrical in male, elongate conical in female (apex narrowly truncate).

Thorax: pronotum: strongly transverse, width male 1.7x length, width female 1.8x length, anteriorly strongly laterally arched, front angles almost hidden by curvature; strongly and closely punctured on disc (puncture diameters c. 2x head punctures, generally separated by one puncture diameter, some coalescent), but basal half midline smooth and impunctate (slightly raised in male), becoming finer and slightly sparser at sides; pronotum with dense recumbent silvery setae except disc [irregularly setose, possibly worn off] and trichobothrium at each angle; anterior and lateral edges finely margined, posterior edge presumed to have row of small teeth as in other Scaphodius species (not seen in entirety); anterior angles rounded, posterior angles posteriorly produced, 90° in perpendicular view; pronotal basal lobe triangular with slightly bilobed apex, basal margin hidden by raised anterior edge of elytra; hypomeron glabrous, impunctate, except densely setose posterior lobe; prosternum closely setose and punctate, anterior margin reflexed; prosternal process transverse, ventral surface flat, laterally bounded by parallel ridges, apex evenly arcuate; scutellum smooth, glabrous and impunctate, minute, length equal width 3rd elytral interval, elliptical; elytra almost quadrate but apices rounded with c. 45° sutural angle; basal margin elytra smooth, slightly overlapping basal margin pronotum; elytra striate, with striole and 10 striae (10th adjacent to epipleuron) but each ‘stria’ consisting of confused fine punctures, with recumbent setae (similar to head), in a straight groove with convex glabrous impunctate interstiae (except base of 9th interval); striae 4 and 5 anastomised before apex, striae 3 and 6, and 7 and 8, at apex; humeri prominent, swelling divided by base of 9th stria; epipleura sparsely and minutely setose, ventrally produced at humeri, broad at base (= width third elytral interval), abruptly narrowed at postcoxae, then narrowing to a single edge before elytral apex; mesoventrite process similar to prosternal process, but shorter, with convex anterior and laterally projecting apical angles; mesanepisternum and mesepimeron glabrous, impunctate, but densely microsculptured; fully winged; metaventrite densely punctured and pubscent at sides, glabrous and transversely strigose (more so in male) at middle; metepisternum densely setose; femora elongate-ovate, similar sized; tibiae gradually expanded to rounded apices, pro- and mesotibiae finely grooved on basal half outer edge; hind tarsi 0.75x length hind tibiae, length metatarsomere 1 <2+3; male first pro- and mesotarsomeres expanded, width 3/5 length, female first tarsomeres not expanded, width 2/5 length; claws appendiculate, lobe large, right-angled.

Abdomen: paired patches of wing-folding spicules on each tergite except pygidium, patches increasing in size from II-VII; pygidium entirely punctured and pubescent with dense recumbent setae, without median ridge; ventrites without lateral ridges, densely punctured and recumbent-setose; ventrite V with truncate apex in both sexes, male with median sparsely setose shallow depression, female ventrite V with deep hemispherical transversely strigose depression and median excavation of apical margins of ventrites III and IV. Male genitalia: spiculum Y-shaped; penis in lateral view with apical half constricted at base, bent towards acute apex; penis dorsally parallel-sided to right-angled apex with blunt tip, pair of setae at base of ostium and c. 11 pairs of setae on apical margin; tegmen broadly Y-shaped, with deep internal keel; endophallic sclerite roughly trident-shaped in dorsal view with oval apical lobes. Female genitalia: vaginal palp elongate-triangular, with darkly sclerotised anterior margin; spermatheca falcate, twisted at base, with uncoiled duct; rectum with well-developed kotpresse: dorsum with rectangular sclerites, simply rounded at their laterally projecting apices, and ovate patch of microspicules; venter with narrow parallel-sided transverse bar, projecting apices greatly expanded; sides with posteriorly directed sclerotised strip.

Notes. Etymology: named for the major endemic language of the island of Ouvea, Drehu ( Anonymous 2010) , a noun in apposition.

Sensory organs on the head are sexually dimorphic in size, as compared against body length, measured from anterior margin of pronotum to apex of elytra: greatest diameter of eye 14.5% (male) or 13.5% (female) body length; antennal length approximately 66% (male) or 50% (female).

Amongst described species of Scaphodius , S. drehu is nearest to S. amieus Schöller, 2009 , which differs by colour, mandibular structure, frontoclypeal margin and penis shape. The female of Scaphodius drehu is most similar to an undescribed species with only females available, from the nearby island of Livou (Loyalty Islands; in BPBM), but S. drehu differs by denser punctures on pronotum, more elongate hind angles of pronotum and broader lines of setae on elytra.

Figures

FIGURES 3–8. Chaloenus gajah sp. nov., male holotype. 3, habitus; 4, head, antero-lateral; 5, head, dorsal; 6, apical ventrite; 7, penis lateral, ventral; 8, tegmen dorsal.

FIGURES 9–13. Scaphodius drehu sp. nov. 9, male, habitus; 10, male head, anterior; 11, male head, lateral; 12, female, habitus; 13, female head, anterior.

FIGURES 14–18. Scaphodius drehu sp. nov. 14, penis lateral, dorsal, endophallic sclerite; 15, tegmen lateral, dorsal; 16, vaginal palp; 17, spermatheca and duct; 18, rectal kotpresse, dorsal (left), ventral (right) (lighter shading = internal spicule patches).