Gelaeus Waterhouse, 1905

Frank, David & Sekerka, Lukáš, 2016, Revision of the subgenusGelaeus of Chrysodema (Coleoptera: Buprestidae: Chrysochroinae), Acta Entomologica Musei Nationalis Pragae 56 (2), pp. 671-719 : 674-679

publication ID	https://doi.org/ 10.5281/zenodo.5310800
publication LSID	lsid:zoobank.org:pub:4CBAE762-D52E-4BE6-99A3-8714B47141DFK
DOI	https://doi.org/10.5281/zenodo.5448853
persistent identifier	https://treatment.plazi.org/id/04548794-6955-FFA1-0FD0-FEFBFBCAFE02
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scientific name	Gelaeus Waterhouse, 1905
status

Treatment

Subgenus Gelaeus Waterhouse, 1905

Gelaeus Waterhouse, 1905: 584 (original description). OBENBERGER (1926): 129 (catalogue); THÉRY (1935): 247 (key to species), 248 (catalogue); KUROSAWA (1982): 190 (as synonym of Chrysodema View in CoL ); BELLAMY (1985): 415 (catalogue); AKIYAMA & OHMOMO (2000): Pl. 42, Figs 445 1–4 (iconography); VOLKOVITSH (2001): 65, 95 (noted); BELLAMY (2003): 35 (catalogue).

Chrysodema (Gelaeus) : KERREMANS (1909): 504 (key to subgenera), 509–511 (key to species, monograph); HOŁYŃSKI (1994): 69 –71 (key to subgenera); LANDER (2003):9 (noted); BELLAMY (2008): 526 (catalogue); HOŁYŃSKI (2014): 373 –375 (key to subgenera).

Type species. Pseudochrysodema walkeri Waterhouse, 1892 , by monotypy.

Differential diagnosis. The subgenus Gelaeus can be immediately recognized by the subtriangular, deep and sharply cut basal impression on each side of pronotum situated approximately at 1/7 width, while other subgenera of Chrysodema do not have this impression. Additionally Gelaeus also has the aedeagus with broad and parallel-sided parameresseparated by a deep cleft, while species of the other subgenera have mostly narrow parameres with shallow cleft, or broad parameres converning from the middle towards apices.

Redescription. Body large (17) 24–34 (38) mm long, metallic coloured, oval, widest in basal 1/5 length of elytra, then parallel-sided and approximately in posterior half strongly tapering apically.

Head slightly narrower than anterior margin of pronotum, metallic coloured with labrum, labium, maxillae and antennal insertions yellow to brownish. Base of scape and antennomeres III–XI yellow to brown, antennomeres I–II metallic coloured. Antennae serrate from antennomere IV. Scape and pedicel sparsely but coarsely punctate. Antennomere III smooth and shiny, IV–XI smooth and shiny with densely punctate dilated parts. All antennomeres elongate, longer than wide. Antennomere III ca. 3× longer than II, antennomeres III and IV subequal, antennomeres gradually shorter from IV except of XI which is distinctly longer than any of VIII–X, VIII–X subequal and ca. 0.6× as long as III. Mandibles metallic coloured and densely and coarsely punctate with smooth cutting edge. Labrum slightly wider than long, deeply emarginate. Eyes large covering approximately lateral 1/4 of head. Genae obvious, densely and coarsely punctate. Frons approximately 2× as wide as diameter of eye, impressed with medial sulcus; coarsely and densely punctate along lower margin and lateral sides, central part sparsely finely to coarsely punctate. Vertex sparsely and coarsely punctate. Whole head with short to moderately long pubescence.

Pronotum trapezoidal, narrowing anteriad, approximately 1.5–1.7× as wide as long. Anterior angles moderately protruding anteriad, obtuse, anterior margin parabolic and densely pubescent. Basal corners angulate, basal margin barely bisinuate. Lateral pronotal carina in form of smooth and impunctate carina interrupted below anterior corners. Disc of pronotum weakly convex with moderately wide medial line and four pairs of impressions ( Figs 1–2 View Figs 1–5 ): a) subtriangular deep and sharply cut basal impression on basal margin situated approximately at 1/7 width of pronotum at base, b) oval shallow to deep principal impression situated approximately at 1/4 width of disc, c) narrow and shallow medial impression situated immediately next to medial line. More or less defined oval lateral impression (d) situated along midlength of lateral pronotal carina. Pronotum with micro- and macropunctation. Micropunctation covers interspaces between macropunctation on whole disc and is visible at magnifications 15–30×. Macropunctation gradually larger and denser from centre to lateral and anterior margins, medial line impunctate. Medial and principal impressions densely punctate but punctures with smaller diameter. Lateral impression usually rugose without separate punctures. Pronotum sparsely and more or less distinctly pubescent. Basically all macropunctures with short seta; setae in anterior corners and principal and medial impressions longer and more obvious.

Scutellum variable in shape, smooth and impunctate.

Elytra weakly convex, in lateral view sinuate with postscutellar area slightly humped, apex somewhat bent upwards. Elytra at base as wide as base of pronotum with several irregular shallow impressions. Basal margin smooth, and not thickened. Lateral margins thickened smooth and nearly impunctate, with more or less distinct angulation below humeral calli. Lateral margins strongly and gradually serrate from the middle to apex, with ca. 12–16 serrations on average. Humeral calli moderately convex and irregularly punctate. Punctation moderate-sized to coarse, closely arranged in more or less distinct striae; inner rows more or less regular, outer ones gradually irregular with multiple punctures. Punctures foveolate, laterally and apically gradually coarser and denser. Intervals at centre nearly impunctate, more or less convex, laterally and apically vanishing. Sometimes intervals and puncture rows interrupted by impressions of small densely arranged punctures with long pubescence (e.g. Figs 8, 11 View Figs 6–11. 6–8 , 32 View Figs 30–35.30–32 ): one situated in basal fourth and one in basal half near lateral margin. In a few taxa there are additional two impressions situated along midline of elytron in basal fourth or half respectively. Whole surface of elytra with sparse very short and recumbent pubescence, laterobasally somewhat longer. Epipleura horizontal, in basal half moderately densely punctate.

Thorax ventrally. Hypomeron densely and coarsely punctate, punctures smaller in basal part. Prosternum distinctly shinier than hypomeron. Basal part of prosternum moderately densely and coarsely punctate, punctures sometimes forming transverse striae. Prosternal process subparallel-sided, narrow, as wide as length of trochanter, sparser but more coarsely punctate, its punctures ca. 2× as coarse as those on base and concentrated at its base and along midline, apex and sides smooth, polished and nearly impunctate, midline more or less impressed. Mesepimeron, and meso- and metanepisterna densely and coarsely punctate. Meso- and metaventrite laterally densely and coarsely punctate, punctures gradually larger but sparser towards midline. Middle parts nearly impunctate. Whole of underside of thorax sparsely pubescent.

Legs. Whole of legs moderately dense and coarsely punctate and pubescent. Femora with two apical ventral teeth, without carinae. Tarsal claws divergent and simple. Legs metallic, only base of trochanter and often tarsi yellow. Sometimes tarsi yellow with more or less metallic ultimate tarsomere, sometimes only claws metallic. Abdominal ventrites laterally densely punctate, centrally and apically very sparsely punctate but punctures much coarser.

Sexual dimorphism distinct in formation of abdominal ventrite V. Males with deep and acute notch, females with shallow notch. Also males on average slimmer than females.

Male genitalia. Aedeagus distinctly longer than wide. Parameres widely separated by deep cleft reaching beyond midlength, often to basal fourth; apices sparsely pubescent, obliquely truncate, exceptionally rounded. Penis from elongate and subparallel-sided to more or less oval and laterally rounded, exceptionally stout-oval; apex acuminate, ventral side with deep central impression nearly for whole length, surface of impression striate.

Distribution. Indonesia: Lesser Sunda Islands and Selayar Islands;? East Timor.

Gelaeus is found all over Lesser Sunda Islands (ca. 6°– 11°S a 116°– 132°E, Fig. 72 View Fig ), however it has not been recorded so far from several larger islands of the archipelago (i.e. Bali, Sumba, Sumbawa, Sawu, and Rote). Nevertheless these islands are poorly explored regarding their insect fauna and some species of Gelaeus might be found there in the future. East Timor is mentioned with a question mark as we mostly have only historical material localized as just Timor without precise locality data.

Remarks. WATERHOUSE (1905: 584) stated the following about Gelaeus : ‘Closely allied to Chrysodema , but differs from all the species of that genus in having two sharply cut impressions at the base of the thorax. Just below the shoulders the elytra are acutely angular. The tarsi are yellow.’ However, only the sharp cut basal impression on the pronotum is diagnostic as the two other characters are present also in other species of Chrysodema . The acutely angular elytra below humeral calli are also present e.g. in C. (C.) mniszechi Deyrolle, 1864 or C. (C.) aurofoveata (Guérin-Méneville, 1830) , the latter being currently considered a junior synonym of C. (C.) radians (Guérin-Méneville, 1830) . It is true that all species of Gelaeus have an acute subhumeral protuberance, however, it displays also great intraspecific variation and is often very small. Most species of Gelaeus have yellow tarsi but some have metallic tarsi (e.g. C. (G.) iris moluensis Novak, 2010 ). Additionally two other species, C. (G.) florensis Lansberge, 1880 and C. (G.) cyanicollis Kerremans, 1900 here assigned to Gelaeus , were placed among Chrysodema s. str. but some authors pointed that they have typical characters of Gelaeus , however rerained them in the nominotypical subgenus ( KERREMANS 1909: 527; LANDER 2003: 17–18).

Key to species of Gelaeus Waterhouse, 1905

1 Pronotum and elytra monochromatic. ............................................................................ 2

– Dorsum dichromatic, pronotum paler and brighter coloured than elytra. ...................... 4

2 Dorsum green or golden-green. Elytra weakly sulcate, striae gently impressed and intervals gently elevated. Lateral impressions distinct. ......................................................... 3

– Dorsum black, only pronotum partly with barely perceptible metallic blue reflections. Elytra profoundly sulcate with deep striae and elevated intervals, without lateral impressions. Endemic to Wetar Is. Figs 54–56 View Figs 54–56 , 71 View Figs 56–71 . ............... C. (G.) wetteriana ( Théry, 1935)

3 Whole of tarsi metallic green. At least posterior lateral impressions of elytra large and round. Nearly whole lateral sides of abdominal ventrites II–III very densely punctate ( Fig. 5 View Figs 1–5 ). Flores Is., Sangeang Is., and Lombok Is. Figs 6–8 View Figs 6–11. 6–8 , 56 View Figs 54–56 . ...................................... ..................................................................................... C. (G.) florensis Lansberge, 1880 View in CoL

– Tarsi pale brown, only last tarsomere metallic green. Lateral impressions of elytra small and oval. Lateral sides of abdominal ventrites II–III basally densely punctate and apically sparsely punctate with large impunctate areas ( Fig. 4 View Figs 1–5 ). Flores Is. and Timor Is. Figs 9–11 View Figs 6–11. 6–8 , 57 View Figs 56–71 . .............................................................. C. (G.) foraminifera Lansberge, 1879 View in CoL

4 Elytra metallic brown, bronze or copper. Pronotum fern green with dark violet tint. ... 5

– Elytra in tones of blue or green. Pronotum bright green with variable tint or blue, exceptionally metallic purple. .................................................................................................. 8

5 Elytra with iridescent pattern. ........................................................................................ 6

– Elytra bronze, copper or dark brown-grey without iridescent pattern. .......................... 7

6 Tarsi pale brown, only ultimate tarsomere metallic green. Iridescent pattern of elytra begins laterally from base. Tenimbar Isls. Figs 12–14 View Figs 12–17. 12–14 , 58 View Figs 56–71 . ............................................... .................................................................................... C. (G.) iris iris ( Kerremans, 1898) View in CoL

– Whole of tarsi metallic green. Iridescent pattern only in apical half of elytra. Molu Is. Figs 15–17 View Figs 12–17. 12–14 , 59 View Figs 56–71 . ........................................................ C. (G.) iris moluensis Novak, 2010

7 Elytra moderately convex in lateral view. Body narrower on average, markedly in males; body length/width ratio in males: 2.97–3.22. Elytra dark metallic brown-violet with more or less bronze intervals. Yamdena Is. Figs 18–20 View Figs 18–23. 18–20 , 60 View Figs 56–71 . ............................................. .......................................................................................... C. (G.) oborili oborili sp. nov.

– Elytra strongly convex in lateral view. Body stouter on average; body length/width ratio in males: 2.79–2.86. Elytra bright bronze to copper. Larat Is. Figs 21–23 View Figs 18–23. 18–20 , 61 View Figs 56–71 . ................ ............................................................................... C. (G.) oborili laratensis subsp. nov.

8 Colouration of elytra in tones of green. .......................................................................... 9

– Colouration of elytra in tones of blue. .......................................................................... 10

9 Lateral sides of abdominal ventrites II–V very sparsely and finely punctate ( Fig. 3 View Figs 1–5 ). Elytra with lighter tone (fern green). Ventral side of body overall with finer and sparser punctation, bright copper-red or copper-golden. Principal impression on pronotum always elongate and shallow. Wetar Is. Figs 48–50 View Figs 48–53.48–50 , 69 View Figs 56–71 . ...................................................... ............................................................................ C. (G.) cupriventris ( Kerremans, 1898) View in CoL

– Lateral sides of abdominal ventrites II–V laterobasally densely and coarsely punctate, apically sparsely but coarsely punctate ( Fig. 4 View Figs 1–5 ). Elytra darker (pine green, exceptionally blue-green or nearly black). Ventral side of body coarsely and densely punctate, dark green with golden or copper reflections. Principal impression on pronotum oval to round and deep. Timor Is. Figs 51–53 View Figs 48–53.48–50 , 70 View Figs 56–71 . .............................................. C. (G.) katka sp. nov.

10 Tarsi pale brown or only ultimate tarsomere metallic green. ....................................... 11

– Whole of tarsi metallic green. Jampea Is., Selayar Is., and Lembata Is. Figs 42–44 View Figs 42–47. 42–44 . ....... ................................................................................ C. (G.) cyanicollis Kerremans, 1900 View in CoL

11 Elytra distinctly sulcate (striae impressed and intervals elevated) at least in apical half, punctures medium sized. Pronotum densely and coarsely punctate thus appearing subrugose. Penis elongate subparallel-sided. ........................................................................ 12

– Elytra smooth without elevated ribs or impressed rows of punctures, latter fine and sparse. Pronotum sparsely punctate and thus appears polished. Penis stout-oval and short. Babar Is. and Wetang Is. Figs 45–47 View Figs 42–47. 42–44 , 68 View Figs 56–71 . .................................................. C. (G.) sara sp. nov.

12 Ventral side of body bright green with golden lustre. .................................................. 13

– Ventral side of body dark green or blue. ...................................................................... 15

13 Whole of tarsi pale brown. ........................................................................................... 14

– Ultimate tarsomere metallic green. Elytra deep blue-violet, apex with purple reflections. Elytra laterally with nearly regular rows of punctures and wide intervals but latter not forming elevated reticulation. Damar Is. Figs 24–26 View Figs 24–29. 24–26 , 62 View Figs 56–71 . ................................................. ..................................................................... C. (G.) walkeri walkeri ( Waterhouse, 1892) View in CoL

14 Elytra uniformly blue without lateral impressions; laterally and apically very densely and irregularly punctate; intervals apically vanishing and punctation not forming distinct rows. Leti Is. Figs 27–29 View Figs 24–29. 24–26 , 63 View Figs 56–71 . ................................... C. (G.) walkeri horaki subsp. nov.

– Elytra blue with lateral impressions, suture and outer margin green; moderately densely punctate, punctures also apically forming distinct rows separated by intervals. Alor Is. Figs 30–32 View Figs 30–35.30–32 , 64 View Figs 56–71 . ......................................................... C. (G.) walkeri rejzeki subsp. nov.

15 Elytra in tones of blue. Apices of parameres obliquely truncate. ................................. 16

– Elytra dark viridian with purple reflections on apical half. Apices of parameres rounded. Moa Is. Figs 33–35 View Figs 30–35.30–32 , 65 View Figs 56–71 . ................................... C. (G.) walkeri nigriventris View in CoL subsp. nov.

16 Elytra dark bluish-black; punctation in rows V–VIII partly irregular. In general elytra more sulcate (striae deeper and intervals more elevated) with coarser punctation. Romang Is. Figs 39–41 View Figs 36–41. 36–38 , 67 View Figs 56–71 . ......................................... C. (G.) walkeri kubani subsp. nov.

– Elytra dark blue; punctation in rows V–VIII forming regular rows. In general elytra less sulcate (striae shallower and intervals less elevated) with finer punctation. Selaru Is. Figs 36–38 View Figs 36–41. 36–38 , 66 View Figs 56–71 . ............................................................ C. (G.) walkeri bilyi subsp. nov.