Microrestes robustus, Bresseel & Constant, 1877

Bresseel, Joachim & Constant, Jérôme, 2020, Microrestes gen. nov., a new genus in the Oriental stick insect tribe Datamini Rehn & Rehn, 1939 with a new species and a new combination (Phasmida: Heteropterygidae: Dataminae), Belgian Journal of Entomology 106, pp. 1-19 : 1-19

Microrestes robustus sp. nov.

urn:lsid:zoobank.org:act:1918EB8F-7DA6-4CE5-B1EE-1D52692CBEAC

( Figs 2–8 )

ETYMOLOGY. The species epithet “robustus ” (adjective, Latin) means firm, solid or robust and refers to the general shape of this species.

TYPE MATERIAL. VIETNAM. Holotype ♀: Hoa Binh prov., Ngo Luong Nat. Res., 20°26’16”N 105°20’15”E, 25-30.VII.2016, GTI Project, Leg. J. Constant & J. Bresseel, I.G.:33.282 ( RBINS).

Paratypes (3♂♂, 3♀♀): 1♀: Tonkin, Région de Hoa-Binh , A. De Cooman, 1934 ( MNHN) ; 1♂: same data as holotype, ex breeding R. Krijns 2018 ( RBINS) ; 2♂♂, 2♀♀: same data as holotype, ex breeding D. Dittmar 2020. (1♂, 1♀: RBINS; 1♂, 1♀: VNMN) .

ADDITIONAL MATERIAL. 5 eggs: same data as holotype, ex breeding D. Dittmar 2020 ( RBINS).

DIAGNOSIS. The new species resembles the only other species in the genus M. trapezius (Ho, 2016) comb. nov., but is slightly smaller and has the body and leg armature much less developed. The anterolateral margins of the mesonotum are only armed with an indistinct tubercle, while they are distinctly spinose in M. trapezius .

DESCRIPTION

MALE ( Figs 2A , 4 , 7 E –F).

MEASUREMENTS: see table 1 .

Head: Supra-antennals and occipitals present as small, blunt spines. Vertex raised and slightly elongated. Supra-orbitals, pro-coronals and anterior coronals present as small, blunt spines; supra-orbitals slightly laterally flattened and larger than pro-coronals and anterior coronals.

Posterior coronals about the same size as anterior coronals. Lateral coronals indistinct and only represented as minute elevations. Postocular carina with a definite blunt spine apically. Eyes relatively small, almost circular in outline and projecting laterally. Antennae shorter than front legs, consisting of 18 segments (n =3); scapus strongly flattened dorsally, laterally carinate and with a median and a subapical blunt spine on outer lateral carina; pedicellus slightly flattened dorsoventrally, indistinctly narrowing towards the posterior and with a blunt spine on outer lateral margin. Third antennomere longer than following two antennomeres combined. Segment XIII with minute spine anterolaterally. Apical antennomere elongated, club-shaped and distinctly longer than preceding segments. Apical five antennomeres yellowish.

Thorax: Pronotum transverse and trapezoidal, widening towards the posterior; anterior margin concave. Lateral margin with small lobe anteriorly, indistinctly undulate towards the posterior. Prozona elevated centrally and with four conical tubercles. Metazona elevated centrally and with two carinae that are armed with four conical tubercles. Posterior margin distinctly wider than anterior margin and straight. Mesonotum trapezoidal with anterior margin wider than posterior margin, anterolateral margin with indistinct granule; anterior margin triangularly raised medially; lateral margin thickened. Mediolongitudinal carina distinct, indistinctly diverging posteromedially; posterior margin concave; anterolateral margin distinctly lower than posterolateral margin in lateral view. Mesopleura widest above coxae; widened portion notched laterally. Metanotum slightly longer than wide, anterior margin slightly wider than posterior one; anterior margin convex, not raised anteromedially; otherwise armed as mesonotum. Metapleura laterally expanding. Prosternum with three sensory areas, lateral ones elongateoval, central one small, circular and not reaching lateral margins of segment. Sensory area on profurcasternum raised, small and circular.

Legs: Femora somewhat rugose with carinae present; dorsal carinae more distinct than ventral ones, medioventral carinae absent. Profemora indistinctly curved basally; dorsal carinae with very faint undulation; with blunt spine posteromedially and unarmed ventrally. Mesofemora slightly shorter than profemora, dorsally with two to three faint, evenly spaced and rounded elevations; ventrally unarmed. Metafemora slightly longer than profemora, armed as mesofemora. Tibiae with carinae indistinct, unarmed ventrally; dorsal carinae with minute, evenly spaced rounded elevations; shorter than or as long as corresponding femora. Tarsomeres very short with a square posteromedian hump dorsally. Claws very small.

Abdomen: Median segment short and distinctly transverse with an obtuse mediolongitudinal carina; posteriorly diverging, forming an inverted Y-shaped elevation; anterior margin convex, posterior margin straight. Abdominal terga rugose and transverse. Terga II–IV gradually narrowing; IV–VII more or less parallel-sided; II–VIII with carina as in median segment; VIII widening towards the posterior with posterior margin concave; IX with mediolongitudinal carina gradually raising towards the posterior but not diverging posteriorly; posterior margin with two granules medially and one submedially; posterolateral angles slightly extended. Anal segment somewhat flattened, incised posteromedially and posterolaterally. Posterolateral angles indistinctly raised and rounded. Poculum with anterior portion rounded and keeled medially, posterior portion distinctly flattened and notched apically. Vomer well projecting over posterior margin of poculum, with a single up-curving distal point. Cerci very small, flattened dorsoventrally and not reaching apex of abdomen. Epiproct short and broadly rounded, only visible in ventral aspect.

FEMALE ( Figs 2B , 5–6 , 7 C–G ).

MEASUREMENTS: see table 1 .

Head: Supra-antennals and occipitals present as small blunt spines. Vertex raised and slightly elongated. Supra-orbitals, pro-coronals and anterior coronals almost continuous, merged into two undulate carinae. Carinae almost touching posteromedially. Posterior- and lateral coronals reduced to rounded tubercles. Postocular carina slightly more raised towards the posterior with a triangular tubercle apically and a smaller one subapically. Eyes relatively small, oval and projecting laterally. Antennae shorter than legs with 19 segments (n =2); scapus strongly flattened dorsally; carinate laterally and with central and subapical, blunt spines on outer lateral carina; pedicellus slightly flattened dorsoventrally, narrowing towards the posterior and with blunt spine on outer lateral margin; third antennomere longer than following two antennomeres combined; segment XV with minute spine anterolaterally; apical antennomere elongated, club-shaped and distinctly longer. Apical antennomere and preceding segment yellowish.

Thorax: Pronotum transverse, trapezoidal and widening towards the posterior; anterior margin concave; lateral margins with small lobe anteriorly, undulate towards the posterior; prozona elevated centrally and with four granules; metazona elevated centrally and with two carinae armed with four granules to tubercles; posterior margin distinctly wider than anterior one and straight. Mesonotum with only few granules dorsally; anterior margin distinctly raised, anteromedially with a pair of granules and anterolateral angles with two small granules; medially with a raised longitudinal carina, diverging near posterior margin; widest anteriorly, laterally carinate and narrowing towards the posterior; anterolateral margin distinctly lower than posterolateral one in lateral view; posterior margin slightly concave. Mesopleura widest above coxae; widened portion undulate laterally. Metanotum with anterior margin concave; distinctly wider than long, more or less parallel-sided with lateral margins carinate; medially with raised longitudinal carina, diverging near posterior margin; portions more or less smooth. Metapleura widest medially, lateral margin undulate. Sensory areas as in male.

Legs: femora with carinae present, anterodorsal carina of profemora slightly raised; apex with medial small granule. Profemora rugose, indistinctly curved basally with posterior part of anterodorsal carina slightly undulate; posterodorsal carina with three evenly spaced minute elevations; ventrally unarmed. Mesofemora slightly shorter than profemora, dorsally with two to three evenly spaced, rounded elevations, ventrally unarmed. Metafemora slightly longer than profemora, armed as mesofemora. Tibiae with carinae indistinct, unarmed ventrally; dorsal carinae with evenly spaced rounded elevations; shorter than corresponding femora. Tarsomeres very short with square posteromedian hump dorsally. Claws very small.

Abdomen: median segment rugose, strongly transverse and with posterior margin more or less straight; medially with raised longitudinal carina, diverging near the posterior margin. Abdominal terga rugose. Terga II–IV gradually widening towards the posterior; IV–V more or less parallel-sided; II armed as median segment; III–V with x-like carinae medially that have the posterior arms more diverging than anterior ones, posterolateral edges triangularly elevated, slightly elongated and thickened with sometimes a small submedial granule posteriorly; VI–X gradually narrowing; VI–VII very short, armed as tergum II. Tergum VIII distinctly longer than VII and slightly ascending, posterolaterally with a spinose granule, centrally with short carina, with pair of granules posteromedially and with two small submedial granules posteriorly, with posterior margin strongly concave; IX distinctly ascending with a well-defined posteromedian

crest formed by two converging carinae, anterior and posterior margins rounded with conical tubercle laterally and sublaterally. Anal segment dorsally flattened; anteriorly with minute median tubercle, sublaterally with oblique row of minute tubercles reaching posterolateral angles, posterior margin straight and granulose, lateral margins with a minute blunt spine medially. Subgenital plate with posterior portion strongly rounded in lateral view, boat-shaped; ventral portion with three longitudinal carinae, one medially and two submedially; widest part

at median portion; posterior margin short, dorsoventrally flattened and rounded apically; not reaching margin of tergum X. Sterna with a mediolongitudinal carina.

NYMPH ( Fig. 7 A–D ). Newly hatched nymphs fairly broad; coloured brown with lateral margins of body paler; paler margins more distinct on abdomen; legs with pale markings; head with complete cephalic armature present ( Fig. 1 ); pronotum trapezoidal; meso- and metanotum with lateral edges thickened and with mediolongitudinal carina; abdominal terga gradually narrowing towards the posterior; median segment and terga II–VIII with posteriorly diverging mediolongitudinal carina.

EGG ( Fig. 8 ). MEASUREMENTS [mm]. Length: 3.1; width: 2.8; height: 3.1.

Egg capsule almost spherical; blackish with minute, brown round markings. Operculum subcircular and slightly convex; capsule and operculum minutely pitted. Micropylar plate slightly raised, trilobate with one anterior expansion and two posterior expansions. Anterior expansion

parallel-sided, reaching to margin of operculum and rounded anteriorly. Posterior expansions projecting laterally, slightly directed towards the anterior and merging ventrally. Micropylar cup indistinct and cup-shaped; median line somewhat raised, reaching polar area.

BIOLOGY. The female holotype of M. robustus sp. nov. was collected on the forest floor in tropical evergreen rainforest. The specimen was found on a narrow trail running through a large, closed patch of Araceae . In captivity nymphs and adults also feed on a variety of Araceae (e.g. Epipremnum spp. , Arum sp. ); but hazel, Corylus avellana L. ( Betulaceae ) and firethorn, Pyracantha coccinea M. ( Rosaceae ) are also accepted as substitute food-plants (pers. com. R. Krijns and D. Dittmar).

Figures

Fig. 2. Microrestes robustus sp. nov., prosternal sensory organs. A, paratype ♂. B, holotype ♀.

Fig. 3. Microrestes spp. distribution map.

Fig. 4. Microrestes robustus sp. nov., paratype ♂ (RBINS). A, habitus, dorsal view. B, habitus, ventral view. C, head and thorax, dorsal view. D, head and thorax, ventral view. E, terminalia, lateral view. F, terminalia, dorsal view. G, habitus, lateral view. H, habitus, dorsolateral view. I, terminalia, ventral view. J, head and thorax, lateral view. K, area apicalis and tarsi.

Fig. 5. Microrestes robustus sp. nov., holotype ♀ (RBINS). A, habitus, dorsal view. B, habitus, ventral view. C, head and thorax, dorsal view. D, terminalia, dorsal view. E, terminalia, ventral view. F, habitus, lateral view. G, habitus, dorsolateral view. H, terminalia lateral view. I, head and thorax, lateral view. J, area apicalis and tarsi.

Fig. 6. Microrestes robustus sp. nov., holotype ♀, in situ. A, dorsal view. B, dorsolateral view.

Fig. 7. Microrestes robustus sp. nov., living specimens. A, newly hatched nymph, lateral view. B, newly hatched nymph, dorsal view. C, female nymph colour variation, dorsal view. D, adult females and nymphs at different stages. E, mating pair, lateral view. F, male and female, dorsal view. G, female, dorsolateral view. A–E, © R. Krijns, F–G, © D. Dittmar.

Fig. 8. Microrestes robustus sp. nov., egg. A, lateral view. B, dorsolateral view. C, dorsal view. D, operculum. E, anterodorsal view. F, polar area.

Fig. 1. Microrestes gen. nov., nomenclature of cephalic armature.

Tables

Table 1. Measurements [mm] of Microrestes robustus sp. nov.

Length of	HT ♀	PT ♂♂	PT ♀♀
Body:	34.0	29.5	33.9
Head:
Pronotum:	3.1	2.4	3.3
Mesonotum:
Metanotum:	3.4	2.8	3.4
Median segment:	1.6	1.3	1.8
Profemora:	6.5	5.0	5.9
Mesofemora:
Metafemora:	6.8	5.6	7.3
Protibiae:	5.7	4.9	5.3
Mesotibiae:	5.0	4.1	5.0
Metatibiae:	7.1	5.6	6.8