Neooxyartes minimus, Bresseel & Constant, 2024

Bresseel, Joachim & Constant, Jérôme, 2024, Stick insects from Vietnam: The new genus Mycovartes gen. nov., with two new species and two new species of Neooxyartes Ho, 2018 (Phasmida: Lonchodidae: Necrosciinae), European Journal of Taxonomy 965, pp. 1-50 : 30-39

Neooxyartes minimus sp. nov.

urn:lsid:zoobank.org:act:6818169D-FE2D-48B4-B21C-AE1AD962A812

Figs 19–26

Etymology

The epithet ‘ minimus ’ is a latin word meaning ‘the smallest’. The name refers to the small body size of the species, since it currently is the smallest species in the genus.

Type material

Holotype VIETNAM • ♂; Gia Lai Province, Kon Ka Kinh N.P. ; 14°12′10″ N, 108°18′40″ E; 6–13 Jul. 2018; 700– 1500 m a.s.l.; GTI project; J. Constant, J. Bresseel and X. Vermeersch leg.; I.G.: 33.769; ex breeding T. Bollens, 2019; RBINS .

Paratypes (21 ♂♂, 24 ♀♀)

VIETNAM – Gia Lai Province • 9 ♂♂, 1 ♀; same data as for holotype; RBINS • 3 ♂♂, 1 ♀; same data as for holotype; VNMN • 2 ♀♀; Kon Ka Kinh N.P. ; 6–13 Jul. 2018; 700–1500 m a.s.l.; 14°12′10″ N, 108°18′40″ E; GTI project; J. Constant, J. Bresseel and X. Vermeersch leg.; I.G.: 33.769; RBINS • 9 ♂♂, 6 ♀♀; same data as for holotype; FH 1171 1 to 16 . – Kon Tum Province • 1 ♀; Kon Plong, Mang Kanh ; 14°39′43″ N, 108°15′45″ E; 16–20 Aug. 2019; GTI Project; J. Constant and J. Bresseel leg.; I.G.: 34.048; RBINS • 8 ♀♀; same data as for preceding; ex breeding Tim Bollens 2020; RBINS • 5 ♀♀; same data as for preceding; VNMN .

Description

Male ( Figs 20–22 , 25A–B, E )

MEASUREMENTS. See Table 3.

BODY. Colouration variable, ranging from pale to dark brown with occasionally some black mottling. Abdominal terga VI–VII often paler than rest of body, sometimes almost white. Legs coloured as body. Antennae coloured as body, tipped in white.

HEAD. Longer than wide, rectangular in dorsal view; dorsal surface flattened with mediolongitudinal groove reaching occiput and posterolaterally with short groove on each side. Eyes more or less circular, slightly displaced towards dorsal surface and strongly projecting laterally. Antennae filiform with 20–22 segments (n = 5) and slightly projecting over front legs; scapus flattened dorsally with inner margin rounded and outer margin straight. Pedicellus shorter, about half the length of scapus, oval in cross-section. Third antennal segment about as long as scapus but distinctly narrower, segment IV about half the length of III; following segments increasing in length to about halfway the antennae and later decreasing in length; apical antennomere more elongated, club-like and about twice the length of preceding segment.

THORAX. Pronotum slightly longer than wide, somewhat shorter than head and indistinctly rugose with pair of faint granules medially on anterior and posterior margins; anterior margin indistinctly concave. Centrally with short transverse impression not reaching lateral edges. Posterior margin almost straight. Mesonotum rugose, slightly longer than two times the length of pronotum, lateral margins more or less straight. Metanotum somewhat rugose, shorter than pronotum, longer than median segment; lateral margins flattened. Prosternum with anterior margin more or less straight, widening towards the posterior; posterior margin concave. Prosternum with three rough “sensory organs”, one medially and pair near bases of front legs. Wings absent.

LEGS. Profemora about as long as corresponding tibiae; compressed and curved basally; dorsal and ventral carinae present and unarmed; medioventral carina absent. Mesofemora about as long as corresponding tibiae, armed as profemora. Metafemora slightly shorter than corresponding tibiae, armed as mesofemora. Tibiae with all carinae present and unarmed.

ABDOMEN. Median segment transverse. All abdominal terga transverse and rugose with lateral margins flattened and somewhat laterally expanding; tergum II shorter than median segment; III–V indistinctly increasing in length; V and VI about the same length; following segments slightly shortening; terga VI– VII with minute posteromedian hump. Tergum X with indistinct mediolongitudinal carina, narrowing towards the posterior with shallow notches near cerci and posteromedially, lateral margins rounded. Ventral portion of posterior margin of anal segment distinctly swollen and with several minute tubercles. Posterolateral angles rounded. Poculum scoop-shaped, rounded; posterior margin flattened and broadly rounded; posterior margin projecting over base of vomer. Cerci not reaching apex of abdomen, more or less triangular with apex rounded and setose. Vomer well developed, distinctly wider than long; basal portion very broad, flattened, slightly narrowing towards posterior portion; posterior portion noticeably constricted and elongated, strongly upcurving with four elongate teeth. Posterior portion of vomer noticeably darker than anterior portion ( Fig. 22 ).

Female ( Figs 23 , 24A–B , 25C–E )

MEASUREMENTS. See Table 3.

BODY. Colouration as in male.

HEAD. Longer than wide, almost rectangular in dorsal view; dorsal surface flat with short carina above eye. Vertex with mediolongitudinal groove reaching occiput and with short posterolateral groove. Eyes more or less circular, slightly displaced towards dorsal surface and strongly projecting.Antennae filiform with 23–24 segments (n = 8) and indistinctly projecting over front legs; shaped as in male.

THORAX. Pronotum slightly shorter than head, slightly widening towards the posterior and somewhat rugose with pair of more distinct granules medially on anterior and posterior margins. Anterior margin gently concave. Centrally with transverse impression not reaching lateral edges. Posterior margin straight. Mesonotum comparatively short and broad, roughly 1.5 times as long as wide and rugose; almost parallel-sided, indistinctly narrowing towards the posterior; posterior margin slightly incurved. Metanotum transverse, slightly longer than median segment and rugose. Prosternum with anterior margin straight, widening towards the posterior; with three rough, almost circular “sensory organs”. Apterous.

LEGS. Profemora slightly longer than mesonotum; compressed and curved basally; all carinae present and unarmed, medioventral carina indistinct; dorsal carinae discretely undulate. Mesofemora about as long as mesonotum; ventral carinae indistinct; unarmed. Metafemora slightly longer than profemora, shaped as mesofemora. Tibiae about as long to slightly longer than corresponding femora and unarmed. Protibiae more or less rectangular in cross-section; probasitarsus short, about as long as following two tarsomeres combined. Meso- and metatibiae simple, rectangular in cross section. Claws small when compared to body size; tarsomeres with small posteromedian extension.

ABDOMEN. Median segment rugose, distinctly wider than long, rectangular and slightly shorter than mesonotum. All abdominal terga transverse and rugose. Terga II–VII indistinctly widening towards the posterior, especially noticeable in living individuals. Tergum VIII narrowing, IX shorter than VIII. Terga II–IX with posteromedian granule/hump, indistinct on tergum II but increasingly enlarging towards tergum IX. Anal segment slightly longer than IX with apical portion somewhat constricted, with indistinct mediolongitudinal carina, apex nearly straight with slight medial indention. Abdominal sternum VII with definite praeopercular organ. Praeopercular organ broad at base, later tapering and resulting in single spine. Subgenital plate reaching about apex of abdomen; apical half spoon-shaped and tapering posteriorly; posterior portion with definite median longitudinal carina. Other abdominal sterna smooth with small black marking posteromedially. Sternum VII with small praeopercular organ present as small, blackish, posteromedian spine. Subgenital plate spoon-shaped, posterior portion carinate, tapering towards the posterior and with apex somewhat triangular, not reaching posterior margin of anal segment. Cerci short not reaching apex of abdomen, flattened, narrowing towards the posterior with triangular, setose apices.

Nymph ( Fig. 25F )

Newly hatched nymphs very small. Head globose, longer than pronotum with dark brown mediolongitudinal dorsal stripe and flanked by longitudinal pale stripes, postocular line orange brown and pale genae. Antennae projecting over front legs, black with few whitish rings. Pronotum with anterior margin broader than posterior margin, coloured as head with postocular line continuing on lateral margins of pronotum. Mesonotum slightly rounded laterally, coloured as pronotum. Metanotum more or less parallel-sided, coloured as mesonotum. Median segment and abdomen terga predominantly orange-brown with dark mediolongitudinal stripe. Legs with pale orange brown femora with dark apex, tibiae with dark base and dark marking centrally. Tarsi and claws whitish.

Egg ( Fig. 26 )

Measurements (in mm): length: 2.1; width: 1.8; height: 2.0.

Capsule almost spherical in lateral view and slightly oval in dorsal view; minutely granulose, predominantly coloured brown with network of minute, dark, mushroom-like armature; central band around egg somewhat darker than posterior area (excluding polar area) and anterior area. Micropylar plate positioned nearly centrally on capsule; almost circular, coloured darker than surrounding capsule; surface reticulated as capsule with mediolongitudinal carina starting at micropylar cup, not reaching anterior margin of micropylar plate. Micropylar cup small, cup-like. Posterior polar area as rest of capsule, somewhat darker with interrupted mediolongitudinal carina directed towards micropylar plate. Operculum oval with ventral margin more broadly rounded than dorsal margin and convex; coloured like capsule with several mushroom-like, stalked granules scattered over surface. Opercular rim somewhat thickened and raised.

Biology

The species was collected in mountainous tropical evergreen rainforest, at a medium to rather high altitude (1500 m in Kon Ka Kinh N.P., 700–1000 m in Kon Plong). The specimens were observed on low vegetation and seemed to feed on a variety of plant species. The eggs are dropped to the ground.

Only females were found in the field, and males were bred from eggs obtained from the wild caught females from Kon Ka Kinh N.P.; only females were bred from the eggs from the Kon Plong population, suggesting the latter population to be parthenogenetic. In captivity, the species accepts Rubus sp. and other Rosaceae , Corylus avellana and Carpinus betulus ( Betulaceae ) as food plants.

Distribution

This species is known from Kon Chu Rang N.R. (Gia Lai Province) and Mang Canh Forest, Kon Plong District (Kon Tum Province) in the central Annamite Mountains ( Fig. 19 ).

Figures

Fig. 19. Neooxyartes Ho, 2018, distribution map.

Fig. 20. Neooxyartes minimus sp. nov., holotype, ♂ (RBINS). A. Habitus, dorsal view. B. Habitus, lateral view. C. Habitus, ventral view. D. Head and thorax, dorsal view. E. Head and thorax, lateral view.

Fig. 21. Neooxyartes minimus sp. nov., terminalia. A. ♂, dorsal view. B. ♀, dorsal view. C. ♂, lateral view. D. ♀, lateral view. E. ♂, ventral view. F. ♀, ventral view. G. ♂, poculum and vomer. H. ♀, left posterior tarsi, I. ♂, left posterior tarsi.

Fig. 22. Neooxyartes minimus sp. nov., ♂ vomer. A. Ventral view. B. Posteroventral view. C. Lateral view.

Fig. 23. Neooxyartes minimus sp. nov., paratype, ♀ (RBINS). A. Habitus, dorsal view. B. Habitus, lateral view. C. Habitus, ventral view. D. Head and thorax, dorsal view. E. Head and thorax, lateral view.

Fig. 24. Neooxyartes minimus sp. nov., in situ.A. ♀, in Kon Ka Kinh N.P. B. ♀, in Kon Plong. C. Habitat.

Fig. 25. Neooxyartes minimus sp. nov. A–B. ♂, dorsal view. C. ♀, dorsal view. D. ♀, dorsolateral view. E. Mating pair. F. Newly hatched nymph. Photographs A, C, F ©T. Bollens.

Fig. 26. Neooxyartes minimus sp. nov., eggs (RBINS). A. Lateral view. B. Dorsal view. C. Dorsolateral view. D. Ventral view. E. Anterolateral view F. Operculum. G. Polar area. H. Variation.