Trichostetha curlei, Perissinotto, Renzo, Sipek, Petr & Ball, Jonathan B., 2014

Perissinotto, Renzo, Sipek, Petr & Ball, Jonathan B., 2014, Description of adult and third instar larva of Trichostetha curlei sp. n. (Coleoptera, Scarabaeidae, Cetoniinae) from the Cape region of South Africa, ZooKeys 428, pp. 41-56 : 42-49

Taxon classification Animalia Coleoptera Scarabaeidae

Trichostetha curlei sp. n.

Type series.

Holotype ♂: South Africa, WC, Elandsberg 33°19'49"S, 21°18'13"E, 1478 m asl, 13 Nov 2013, JB Ball & R Perissinotto (ISAM). Paratypes, 16♂ 2♀: same data as above (ISAM, PCBM, PCRP); 5♂ 1♀, same locality, but 16 Nov 2009, HC Ficq (PCAC); 2♂ 2♀, same locality, but 14 Nov 2011, HC Ficq (PCAC).

Etymology.

The species is named after the South African lepidopterist AI Curle, who brought to our attention the existence of this undescribed Cetoniinae from the Elandsberg range.

Description of adult

(Figures 1-4). Male, holotype. Size: length 18.0 mm; width 9.2 mm.

Body (Figure 1A). Dark green to black; long white setae and white tomentose marks widespread, particularly on elytral surface.

Head. Black with scattered whitish, long setae and dense round punctures; clypeus sharply upturned, with broad anterior margin rounded, depressed at centre, forming two lateral lobes, which together with marked lateral ridges form concavity with raised frons at middle; antennal club, pedicel and flagellum black; antennal club short, pedicel and flagellum with long, erected white setae.

Pronotum. Dark green to black, shiny; disc without setae and with only few small, shallow punctures; scattered round punctures becoming larger and denser towards lateral margins; short setae restricted to lateral declivity; white tomentum restricted to stripe on lateral margins and two basal spots near posterior margin in shallow depression anteriad of scutellar basal corners; postero-lateral angle slightly rounded, posterior margin mildly sinuate anteriad of scutellum; anterior margin straight and as wide as eyes.

Scutellum. Dark green, shiny with sharply pointed apex and deep lateral grooves; few, scattered small punctures bearing short setae mainly around basolateral corners.

Elytron. Dark green to black; with sparse but very long white setae; humeral and third costa sharply raised and very marked; umbone wider than pronotum; small sparse white maculae, denser on second and fourth elytral striae where they form dotted lines, larger maculae present on lateral and apical declivity; crescent to horseshoe punctures distributed throughout surface, becoming more irregular in shape and scattered on umbone, costae, lateral and apical declivities.

Pygidium. Black with long white setae; with extensive white markings in basal two thirds, on each side of midline.

Legs. Protibia with few short setae, tridentate, with proximal denticle drastically reduced; distal teeth very pointed; anterior arolium bisetose; mesotibia with many long setae and two median external denticles, proximal extremely reduced, distal furcate and pointed outwardly; mesotibial claws sharply bent to form hook-like structure; metatibia covered in long setae, with median outer ridge not very pronounced, posterior arolium bisetose; all femora covered in dense, long white setae.

Underside (Figure 1B). Dark green, shiny, with dense setation and scattered punctures covering entire surface, except parts of mesometasternal process, medial half of abdominal sternites and ventral surface of metafemora; mesosternal lobe simple and flat, not protruding; sternites 3-6 with deep medial concavity.

Aedaegus (Figure 2). Parameres tapering gradually into sharply pointed apical end, gently curved downwards at apical half; without setae.

Female, paratype (Figure 3). Size: length 17.3 mm; width 8.9 mm. General shape and colour patterns similar to male, but white marks substantially reduced throughout body surface; white setation drastically reduced both on dorsal and ventral surfaces; tarsal segments shorter and protibial denticles wider and rounded; wing surface approximately one fifth smaller than in male; sternites 3-6 with slight medial convexity.

Variability.

Males range from 12.9 to 18.0 mm in length and from 7.0 to 9.0 mm in width (n = 24), while females vary between 15.5 and 17.3 mm in length and between 8.2 and 8.5 mm in width (n = 2). All specimens exhibit a dark green to black dorsal colour, but there are brown areas on elytral disc in some cases. The extent of white maculation throughout the surface can also change substantially among specimens. The male pronotum occasionally exhibits second and/or third smaller discal spots in shallow depressions towards the lateral declivity, at middle or near the anterior margin.

Diagnosis.

Trichostetha curlei sp. n. is most closely related to the smaller species of the genus, Trichostetha dukei and Trichostetha hawequas . It differs from both in having extremely well developed white pilosity in the male, sharp elytral costae, dark green background colour and extensive white maculation on the pygidium (Figures 1, 3, 4).

Remarks.

It appears that, despite being seen on numerous flowers in different plant families, the univoltine adults are unable to feed and are active for a relatively short period of time at the onset of summer, from mid November to mid December. Their observed behavior is unexpected for a member of the genus Trichostetha , in that they show very little flying activity, preferring rather to perch on leaves and flowers of a variety of shrub species (Figure 4), which may serve as mating platform. Adults were noted on a number of plants, including Leucadendron rubrum (both male and female flower heads), Protea eximia , Passerina truncata , Elegia filacea (both male and female flowers) and Cullumia bisulca .

Description of third instar larva

(Figures 5-6). Material examined. Two third instar larvae with the following data: South Africa, Western Cape Province; Elandsberg, 13 Nov 2013, JB Ball & R. Perissinotto legit.

Body (Figure 5A). Larva scarabaeiform, of typical Cetoniinae habitus, maximal length 38-41 mm; cranium brown to dark-brown, body densely setose, creamy-white or greyish, setae yellowish to orange-brown; abdominal segments IX and X fused dorsally, ventrally separated by an incomplete groove.

Head capsule (Figure 5B). Maximum width between 3.3 and 3.6 mm; cranium glabrous with linear microsculpture, brown; antennifer, postclypeus and labrum darker, frontoclypeal suture and apices of mandibles black; frontal sutures shallowly bisinuated; epicranial insertions of antennal muscles feebly developed (visible only as small depressions near the midline of frontal sutures); epicranial suture extending anteriorly into frons; cranial chaetotaxy summarized in Table 1; posterior epicranial setae with a single long and several minute setae; anterior frontal setae absent, exterior frontal setae minute; clypeus almost rectangular, membranous anteclypeal part covering about 1/3 of entire clypeal area; postclypeus strongly sclerotized with one anterior and a pair of exterior clypeal setae (one shorter than the other); frontoclypeal suture distinct; stemmata rudimental.

Antennae (Figures 5G, H). Four-jointed (an I–IV), relative length of antennomeres: an I> an IV> an II> an III; an III with ventral, apical projection exhibiting a single sensory spot; roud (apical) sensorial field of ultimate antennomera shifted slightly laterally; two dorsal and two ventral sensorial spots present.

Labrum. Symmetrical, anterior margin trilobed with numerous setae; clithra present; dorsal labral surface with two transverse rows of setae.

Epipharynx (Figure 5C). Haptomerum with zygum convex, with a transverse row of 12-15 spiny setae, eight to ten similar setae at posterior base of haptomerum; sensilla of zygum grouped below apex of haptomerum; haptomeral process and proplegmata absent; acroparia with external margin of lateral labral lobes with six long setae on ventral and four setae on dorsal side; medial labral lobe with two rows of four setae; acanthoparia bearing five to seven setae with distinctly swollen base (projecting out of epipharyngeal margin); lateral margin of epipharynx serrate; subapical seta of acanthoparia slightly longer than posterior setae, apical seta about three times longer than subapical seta; plegmata absent; chaetoparia with about 60 setae arranged in three to four irregular rows, medial rows with stout, spine-like setae; dexiotorma robust, straight; right pternotorma present; laeotorma short, left pternotorma triangular, large; haptolachus with sense cone (left nesium) low and obtuse, sclerotised plate (right nesium) absent; plate-shaped sclerite feebly developed; anterior part of haptolachus (distad to sense cone) with short spine-like setae; postero-lateral part with group of two pore-like setae on each side; phoba and crepis absent.

Mandibles (Figure 6 A–F). Asymmetrical, scrobis with four to six setae; longitudinal furrow absent; anterolateral portion of dorsal mandibular surface with two setae (often broken); interior seta more or less distinct, exterior seta short, indistinct; patches of two to four dorsomolar and ventromolar setae concealed in single rim on both mandibles (however, dorsomolar setae were absent on one of two left mandibles examined); stridulatory area with seven to ten transversal ridges; left mandible with four and right mandible with three prominent scissorial teeth; apical third of external mandibular margin with prominent obtuse or slightly pointed tubercle; molar lobes of both mandibles with sharp projections; posterior margin of right madibular calyx bilobed (in medial aspect), dorsal lobe about twice as large as ventral; calyx of left mandible flattened with convex posterior margin; brustiae with 5-7 and 10-13 setae on right and left mandible, respectively.

Maxilla (Figures 5D, E). Dorsal surface of cardo and labacoparia with 10-14 and 12-13 setae, respectively; ventral surface of cardo with 2-3 and 21-28 setae, respectively; stipes with around 21-31 slender hair-like setae dorsally and 2-3 long stout setae at external margin; stridulatory area composed of 6-8 well sclerotised spine-like stridulatory teeth organized in oblique raw; truncate process (blunt tubercle) present; ventral face of stipes with single prominent seta at proximal margin and transverse, prominent group of seven setae at base of maxillary palpi; galea and lacinia entirely fused forming mala, galeo-lacinial suture indistinct, entirely absent on ventral surface; galear portion of mala with single falcate uncus and 9-11 long hair-like setae in longitudinal rows; lacinial part of mala with one large and one small uncus and a minute conical seta at base of larger uncus; dorso-medial side with 16-20 very long hair-like setae; setae proximal to galear and lacinial unci generally shorter and stouter than other setae; ventral surface of mala with two longitudinal rows of 3-5 stout setae and basal transverse group of 3-4 hair-like setae; maxillary palps four–jointed, penultimate joint with two setae.

Hypopharyngeal scleroma (Figure 5D). Asymmetrical with strong protruding and pointed truncate process; tufts of tegumentary expansions (= phoba, sensu Böving 1936) present on left lateral lobe, but absent on central portion of hypopharyngeal scleroma (at base of truncate process); two additional tegumentary expansions below medio-lateral margin of hypopharyngeal scleroma; lateral lobes only feebly sclerotized, anterior margin of left lobe with 12 setae, anterior margin of right lobe with 6-9 setae.

Ligula (Figure 5D). Dorsal surface with group of approximately 15-20 long hair-like setae on each lateral margin; paramedial longitudinal row of 3-4 stout setae and proximal transverse row of 12-14 campaniform sensilla interrupted by central pair of conical setae; labial palpi two–jointed.

Thorax (Figures 5A, F; 6H). First thoracic sublobe densely setose, with approximately 12 transverse rows of setae; posterior margin of prothoracic sclerite with about 10 setae on dorsal and four setae on ventral surface; each sublobe of meso- and metathoracic segments with 3-6 rows of dorsal setae, anterior row(s) generally with shorter setae than posterior rows; respiratory plate of mesothoracic spiracle “C” -shaped, 0.4 × 0.25 mm (height × width) (Figure 7H); distance between lobes almost equal to maximal diameter of respiratory plate; respiratory plate with 15-20 holes across diameter; all pairs of legs subequal (Figure 5A, F); pretarsi cylindrical with 7-8 setae and minute pointed tip.

Abdomen (Figures 5A, 6G). Nine-segmented, densely setose; dorsi of abdominal segments I–VI with three sublobes, VII and VIII with only two; each sublobe bearing six to ten rows of setae; like in thorax, setae in anterior rows shorter than in posterior rows; abdominal spiracles more concealed than mesothoracic spiracle, distance between lobes of respiratory plate equal or shorter than half maximal diameter of respiratory plate; all spiracles subequal in size; abdominal spiracles on segment VI–VIII more circular than preceding ones; dorsum of last abdominal segment entirely covered with medium to long hair-like setae; hammate setae absent.

Raster (Figure 6G). Palidium monostichous (however few irregular pali scattered around main row and on ventral anal lobe), composed of two rows of approximately 15-19 short, spine-like pali; septula posteriorly open, about three times longer than wide; tegilla not separated from other groups of setae, entire venter of last abdominal segment covered with hair-like setae interspersed with few spine-like setae; ventral and dorsal anal lobes with numerous medium to long setae, transverse anal row of dense setae absent.