Orestes Redtenbacher, 1906

Joachim Bresseel & Jérôme Constant, 2018, The Oriental stick insect genus Orestes Redtenbacher, 1906: Taxonomical notes and six new species from Vietnam (Phasmida: Heteropterygidae: Dataminae), Belgian Journal of Entomology 58, pp. 1-62 : 5-9

Genus Orestes Redtenbacher, 1906

Type species: Orestes verruculatus Redtenbacher, 1906 by original monotopy.

Orestes REDTENBACHER, 1906: 47 [described].

Orestes – REHN & REHN, 1939 [attributed to Datamini ]. — BRAGG, 2001 [type specimen data]. — ZOMPRO, 2004 [redescribed]. — HO, 2013 [recorded from China]. — SEOW- CHOEN, 2017 [recorded from Singapore]. — BROCK et al., 2017 [catalogued].

DIAGNOSIS.

♂♂, ♀♀: moderately sized Datamini (body length ♂♂ 34.0–45.0 mm, ♀♀ 42.6–54.4 mm), apterous and strongly cryptic. Body robust, surface granulose to tuberculose; colouration with different shades of brown to black, sometimes whitish. Head armature arranged as in Fig. 1 , from almost indistinct to crest-like. Thorax cylindrical to subcylindrical in cross-section. ♀♀ with mesonotum slightly widening towards the posterior, often with mediolongitudinal line and two rows of tubercles sublaterally. Legs with carinae often indistinct, most distinct carina is the anterodorsal carina of the profemora. Abdomen dilated centrally, with posterior “wart” on terga IV-V; tergum IX with distinct posteromedian crest. Subgenital plate cup-like, not projecting over anal segment. ♂♂ distinctly smaller and narrower than ♀♀ with mesonotum and abdomen almost parallel-sided. Poculum relatively large and triangular to cup-like from lateral view. Legs as in female.

Eggs: egg capsule spherical to subspherical. Operculum shape variable elongated to circular and slightly convex. Capsule and operculum covered with long setae with a distal black twoto four-hooked grapnel-shaped structure. Micropylar plate trilobate with one anterior expansion and with two posterior expansions; posterior arms directed laterally and projecting on sides of capsule. Margin of micropylar plate sometimes indistinct. Micropylar cup small, black, cup-shaped and protruding.

The genus was redescribed by ZOMPRO (2004) upon both sexes and the egg. ZOMPRO’ s description is based on material of O. mouhotii ( Bates, 1865) from Nakhon Ratchasima, Thailand. In the species description, he stated that the widest abdominal segment is segment V. However, the posterior margin of tergum IV is slightly wider than V in O. mouhotii and all species of Orestes . Some species can have terga IV-V almost parallel-sided, whereas other species have tergum V with distinctly oblique lateral margins.

DIFFERENTIATION.

The genus Orestes differs from all other known genera of Datamini Redtenbacher, 1939 by the following combination of characters:

1) Mesonotum semicylindrical without distinctly raised mediolongitudinal and lateral carina; mediolongitudinal line sometimes present, sometimes slightly elevated in males. 2) Females with widest part of body at the posterior margin of tergum IV, sometimes tergum IV-V almost parallel-sided.

3) Anal segment almost parallel-sided, never triangular or strongly tapering towards the posterior; posterior margin more or less straight.

4) Anal segment in females dorsally flattened, with two distinct lamellate or tuberculose oblique carinae reaching posterolateral angles.

5) Females with terga IV-V with a wart-like structure posteriorly and tergum IV being the highest part of the abdomen.

The most closely related genus is Pylaemenes Stål, 1875 . However, Pylaemenes has the meso- and metanotum flattened or slightly tectiform and with distinct raised mediolongitudinal and lateral carinae; the anal segment of females is strongly triangular in dorsal aspect and distinctly notched apically; the males have tergum IX strongly widened posteriorly and oblique laterally ( Fig. 2 : P. coronatus (Haan, 1842) , the type-species of Pylaemenes ).

BIOLOGY. All species were collected in tropical evergreen rainforest, at low to moderately high altitude (50–1500 m). In Vietnam and Cambodia the specimens were observed on low vegetation, usually very close to the ground (below 50cm) but sometimes up to 1.5–3 m from the ground. They seemed to be exclusively nocturnal and appeared to feed on a variety of plant species with a preference for Araceae .

DISTRIBUTION. Far Eastern Palaearctic and Oriental Regions: China, Vietnam, Cambodia, Thailand, Sumatra, Japan, Taiwan.

Species included

1. O. bachmaensis sp. nov. [Vietnam: Bach Ma N.P., Phong Dien VNMN Station]

2. O. botot sp. nov. [Vietnam: Bidoup Nui Ba N.P.]

3. O. diabolicus sp. nov. [Vietnam: Bidoup Nui Ba N.P.]

4. O. dittmari sp. nov. [Vietnam: Cat Ba N.P.]

5. O. draegeri sp. nov. [Vietnam: Cat Tien N.P., Dong Nai Biosphere Reserve]

6. O. guangxiensis ( Bi & Li, 1994) comb. nov. [China: Fujian, Guangdong, Guangxi, Hainan, Hong Kong]

= Pylaemenes hongkongensis Brock & Seow-Choen, 2000

7. O. krijnsi sp. nov. [Vietnam: Nui Chua N.P.]

8. O. japonicus ( Ho, 2016) comb. nov. [Japan: Yakushima]

9. O. mouhotii ( Bates, 1865) [Cambodia, Tatai, Kirirom N.P.; Thailand: Bangkok, Chantaburi, Nakhon Ratchasima; Sumatra: Medan; Singapore]

= O. verruculatus Redtenbacher, 1906

= Dares fulmeki ( Werner, 1934)

10. O. shirakii ( Ho & Brock, 2013) comb. nov. [Taiwan: Taipei]

11. O. subcylindricus ( Redtenbacher, 1906) comb. nov. [Vietnam: Mt Mauson, Cuc Phuong N.P., Ngo Luong N.R., Tay Ten Tu N.R.]

Keys to the species of Orestes from Cambodia and Vietnam

Figs 3–5

MALES

1. Supra-coxal spine on mesopleuron strongly projecting laterally ( Fig. 3 A ) ......................... 2

- Mesopleuron without a distinct elongated supra-coxal spine ( Fig. 3 B–C ) .......................... 3

2. No elongated spines on pro- and mesonotum or on median segment ( Fig. 3 D ) .................... ....................................................................................................................... O. botot sp. nov.

- A pair of strong, elongated spines on pronotum, two pairs on mesonotum and one on median segment ( Fig. 3 G ) ................................................................... O. diabolicus sp. nov.

3. Head without central coronal ( Fig. 3 J, M–N )....................................................................... 4

- Head with central coronal ( Fig. 3 K–L, O ) ........................................................................... 6

4. Anterior coronals distinctly enlarged; blunt and laterally compressed, creating ear-like processes; posterior margin of metanotum not raised ( Fig. 3 J, N )....................................... 5

- Anterior coronals spinose, not laterally compressed; posterior margin of metanotum raised ( Fig. 3 M ).................................................................................................... O. krijnsi sp. nov.

5. Posterior margin of mesonotum not distinctly raised, armed with two small tubercles ( Fig. 3 E ) ................................................................................................ O. mouhotii ( Bates, 1865)

- Posterior margin of mesonotum conically raised, sulcate medially ( Fig. 3 C, F ) ................... ................................................................................................................. O. draegeri sp. nov.

6. Supra-orbitals and anterior coronals lamellate ( Fig. 3 L )........................................................ .............................................................. O. subcylindricus ( Redtenbacher, 1906) comb. nov.

- Supra-orbitals and anterior occipitals spinose ( Fig. 3 K, O ) ................................................. 7

7. Coronals not fused basally; anterior coronals rounded apically ( Fig. 3 K )............................. .................................................................................................................. O. dittmari sp. nov.

- Anterior-, central- and posterior coronals fused basally, together into a raised crest; anterior coronals acute ( Fig. 3 O ) .................................................................. O. bachmaensis sp. nov.

FEMALES

1. Head with a lamellate elevation on vertex ( Fig. 4 A–B, D ) .................................................. 2

- Head without lamellate elevation, vertex granulose to tuberculose ( Fig. 4 C ) ..................... 5

2. Tergum IX with posteromedian crest distinctly notched posteriorly ( Fig. 4 E ); tergum V with posterior margin indistinctly narrower than anterior margin ........................................ 3

- Tergum IX with posteromedian crest strongly tectiform and not distinctly notched anteriorly, with apex narrow ( Fig. 4 F ); tergum V with posterior margin distinctly narrower than anterior margin .............................................................................................................. 4

3. Supra-coxal spine on mesopleuron small but acute and projecting laterally ( Fig. 4 I ); posterior margin of mesonotum slightly raised with two short oblique carinae; terga III-IV without posterolateral elevated tubercle ........................................................ O. botot sp. nov.

- Mesopleuron without a supra-coxa spine, at best present as a small tubercle ( Fig. 4 J ); posterior margin of mesonotum not raised; terga III–V with a distinct, raised tubercle posterolaterally ..................................... O. subcylindricus ( Redtenbacher, 1906) comb. nov.

4. Outer ventral carinae of meso- and metafemora with two laterally compressed and rounded teeth posteriorly ( Fig. 4 M ); abdominal sternum VII with a conspicuous medial compound tubercle anteriorly............................................................................. O. bachmaensis sp. nov.

- Outer ventral carinae of meso- and metafemora unarmed, or with two tubercles posteriorly ( Fig. 4 N ); abdominal sternum VII with at best an indistinct pair of tubercles in the anterior half............................................................................................................ O. dittmari sp. nov.

5. Tergum IX with posteromedian crest notched posteriorly ( Fig. 4 H ) ..................................... ....................................................................................................... O. mouhotii ( Bates, 1865)

- Tergum IX with posteromedian crest elongated, strongly tectiform and not visibly notched anteriorly, and narrow apically ( Fig. 4 G ) ............................................................................. 6

6. Meso- and metatibiae unarmed; tergum IV distinctly widening towards the posterior ( Fig. 4 L ) ............................................................................................................. O. krijnsi sp. nov.

- Meso- and metatibiae with a laterally compressed, central tooth dorsally; tergum IV indistinctly widening towards the posterior, almost parallel-sided ( Fig. 4 K )

................................................................................................................. O. draegeri sp. nov.

Figures

Fig. 2. Pylaemenes coronatus (Haan, 1842). A, ♂ from Indonesia, Molucca, West-Seram, X.2012 (RBINS), habitus dorsal view. B,♀ from same origin, III.2013(RBINS), habitusdorsal view.

Fig. 3. Orestes spp., diagnostic characters of ♂♂ (not to scale). A–C, mesonotum dorsal view. A, O. botot sp. nov. B, O. subcylindricus (Redtenbacher, 1906) stat. rev. comb. nov. C, O. draegeri sp. nov. D–I, mesonotum lateral view. D, O. botot sp. nov. E, O. mouhotii (Bates, 1865). F, O. draegeri sp. nov. G, O. diabolicus sp. nov. H, O. krijnsi sp. nov. I, O. bachmaensis sp. nov. J–O, head lateralview. J, O. draegeri sp. nov. K, O. dittmari sp. nov. L, O. subcylindricus (Redtenbacher, 1906) comb. nov. M, O. krijnsi sp. nov. N, O. mouhotii (Bates, 1865). O, O. bachmaensis sp. nov. Cc = central coronal.

Fig. 4. Orestes spp., diagnostic characters of ♀♀ (not to scale). A–D, head, lateral view. A, O. bachmaensis sp. nov. B, O. dittmari sp. nov. C, O. draegeri sp. nov. D, O. subcylindricus (Redtenbacher, 1906) comb. nov. E–H, apex of abdomen, anterolateral view. E, O. botot sp. nov. F, O. dittmari sp. nov. G, O. krijnsi sp. nov. H, O. mouhotii (Bates, 1865). I–J, mesonotum, lateral view. I, O. botot sp. nov. J, O. subcylindricus (Redtenbacher, 1906) comb. nov. K–L, abdomen dorsal view. K, O. draegeri sp. nov. L, O. krijnsi sp. nov. M–N, metafemur, lateral view. M, O. bachmaensis sp. nov. N, O. dittmari sp. nov. C = carina; PmN = posteromedian notch;PlM = posterolateral margin.

Fig.5. Orestes. spp., distribution map.

Fig.1. Orestes Redtenbacher, 1906,nomenclature of cephalic armature.