Pterohirasea nigrolineata, Bresseel & Constant, 1835

Bresseel, Joachim & Constant, Jérôme, 1835, Two new stick insect genera from Vietnam, Nuichua gen. nov. and Pterohirasea gen. nov. with two new species (Phasmida: Diapheromeridae: Necrosciinae), Belgian Journal of Entomology 70, pp. 1-29 : 1-29

Pterohirasea nigrolineata sp. nov.

urn:lsid:zoobank.org:act:08146329-89F9-4C44-AD0D-6A120A5BEC84

Figs 8–14

ETYMOLOGY. The species name is derived from niger (adj., Latin) meaning black, and lineatus (adj., Latin) meaning striped. It refers to the black longitudinal stripe marking the body of the species.

TYPE MATERIAL. VIETNAM: holotype ♂ ( Fig. 10 ): C Vietnam, Bach Ma N. P., 16°12’N 107°52’E, 12–17.VII.2011, leg. J. Constant & J. Bresseel, I.G.: 31.933 ( RBINS) .

Paratypes [20♂♂, 20♀♀, 4♀♀ penultimate stage, 2 nymphs]: 1♂, 3♀♀, 4♀♀ nymphs penultimate stage: C Vietnam, Bach Ma N. P., 16°12’N 107°52’E, 12–17.VII.2011, leg. J. Constant & J. Bresseel, I.G.: 31.933 (2♀♀, 2♀♀ nymphs penultimate stage: RBINS; 1♂, 1♀, 2♀♀ nymphs penultimate stage: VNMN) ; 1♂, 2♀♀: Vietnam, Thua Thiên-Huê Prov., Phong Dien near VNMN station, 16°35’12”N 107°20’31’’E, 8-9.IV.2017, leg. J. Constant & J. Bresseel, I.G.: 33.447 ( RBINS) ; 1♂ Vietnam, Thua Thiên-Huê Prov., Bach Ma N.P., 16°12’N 107°52’E 10-16.IV.2017, leg. J. Constant & J. Bresseel, I.G.: 33.447 ( RBINS) ; 15♂♂, 15♀♀: ex breeding Tim Bollens 2018, origin: Vietnam, Thua Thiên-Huê Prov., Phong Dien near VNMN station, 16°35’12”N 107°20’31’’E, 8-9.IV.2017, leg. J. Constant & J. Bresseel, I.G.: 33.447 (11♂♂, 11♀♀: RBINS; 4♂♂, 4♀♀: VNMN) ; 3♂♂: Annam, Lién Chién près Tourane, 0 à 1000 M d’alt., Mme Poilane , 1923 ( MNHN) .

NOTE

Tourane is the older name of Da Nang, hence the location name “Lién Chién” is most probably a misspelling of Liên Chi ểu (coordinates: 16°07′26″N 108°07′4″E)

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ADDITIONAL MATERIAL. VIETNAM: 75 eggs: ex breeding J. Bresseel, 2017, origin: Vietnam, Thua Thiên-Huê Prov., Phong Dien near VNMN station, 16°35’12”N 107°20’31”E, 8- 9.IV.2017, leg. J. Constant & J. Bresseel, I.G.: 33.447 (50 eggs: RBINS; 25 eggs: VNMN) .

ADDITIONAL DATA. VIETNAM: several nymphs (not collected): Da Nang Province, Ba Na-Nui Chua Nat. Res., 16°00’N 108°01’E, 16-19.VII.2017, J. Constant & J. Bresseel .

DESCRIPTION

MALE ( Figs 10–11 , 13 C–I , 14 A–C )

Measurements: see table 2.

Body: ( Fig. 10 A–C ) head orange- to dark brown with paler granules; broad black postocular line and a dark marking dorsally. Antennae black with white rings. Pro-, meso and metanotum orange- to dark brown with paler granules and a broad black mediolongitudinal line. Median segment and abdominal terga II–VII brown with a broad, black longitudinal line; sometimes present on all segment excluding anal segment. Terga II–IX with a pale marking anterolaterally. Legs orange- to dark brown. Coxae with a yellowish marking posteriorly, femora and tibiae with minute pale markings. Meso- and metapleura with a definite yellow marking. Thoracical and abdominal sterna cream to light brown with posteromedian black marking.

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21 Head: ( Figs 10 D, G , 14 C ) longer than wide and mainly smooth, with few distinct, pale granules dorsally and on genae; dorsal surface slightly flattened with distinct mediolongitudinal groove. Vertex rounded, posterolaterally also with a groove. Between eyes, a small raised area; anteriorly of raised area a shallow indention. Eyes circular and strongly projecting hemispherically. Antennae distinctly projecting over front legs. Scapus slightly flattened dorsoventrally and oval in cross-section. Pedicellus short, knob like and round in cross-section.

Thorax: ( Figs 10 D, G , 13 H , 14 C ) pronotum slightly shorter than head with few pale granules; anterior margin strongly incurved with anterolateral angles extended and apically rounded. Base of anterolateral extensions with a minute peudoforamen. Posterior portion slightly widening towards posterior margin. Median longitudinal groove starting anteriorly, not reaching posterior edge. Centrally with a short transverse impression not reaching lateral edges. Posterior margin rounded. Mesonotum about as long as mesofemora, with few pale granules and parallel-sided. Metanotum with few pale granules, slightly longer than median segment, subapically with a small hump followed by a short transverse median furrow. Prosternum with anterior margin straight, widening towards the posterior; posterior margin concave. Prosternum with rough paired, almost circular sensory organs; longitudinally divided by a median furrow ( Fig. 9 ). Mesosternum with few, minute pale tubercles laterally. Meso- and metasternum with a small, black elevation posteriorly.

Wings: ( Figs 10 D, G , 13 H , 14 C ) tegmina absent. Alae small, not reaching median segment; costal area blackish with inner margin reddish; anal area bright red.

Legs: ( Fig. 10 A–C ) profemora slightly longer than pro- and mesonotum combined; compressed and curved basally; outer dorsal and ventral carinae present and unarmed; medioventral carina indistinct. Mesofemora about as long as mesonotum; ventral carinae indistinct. Metafemora slightly longer than profemora, armature as in mesofemora. Protibiae slightly longer than head, pro- and mesonotum combined; subrectangular in cross-section with outer ventral and dorsal carinae developed; carinae with small setae. Probasitarsus longer than all following tarsomeres combined. Mesotibiae slightly longer than mesofemora; carinae as in protibiae, with medioventral carinae present, but indistinct. Metatibiae distincly longer than metafemora; carinae as in mesotibiae. Meso- and metatarsi with claws small when compared to body size; tarsomeres with a small posteromedian extension.

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23 Abdomen: ( Figs 10 A–C, E–F, H–I , 13 I ) median segment longer than wide, slightly trapezoidal and subapically with a black transverse hump medially. All abdominal terga less than two times longer than wide with few pale granules. Terga II–IX with a minute posteromedian hump; tergum II slightly longer than median segment; III–V about the same length; tergum VII distinctly shorter than V, widening towards the posterior; VIII distinctly wider than long, widening posteriorly with a mediolongitudinal carina; tergum IX slightly shorter than VIII and tectiform; tergum X shorter than IX with mediolongitudinal carina; slightly concave apically with outer margin slightly setose. Ventral portion of outer margin of anal segment slightly swollen and with several black tubercles. Posterolateral angles rounded. Poculum rounded; posterior margin flattened with outer rim curving downwards; reaching about base of vomer. Cerci reaching about apex of abdomen, laterally flattened with apices rounded, slightly incurving and distinctly setose. Vomer well developed and large; basal portion broad, flattened and almost semicircular; posterior portion tapering, strongly upcurving and notched apically, forming two apices; apices blackish and tapering towards a fairly blunt apex ( Fig. 11 ).

FEMALE ( Figs 12 , 13 J–N , 14 D–F )

Measurements: see table 2.

Body: ( Fig. 12 A–C ) colouration as in male, distinctly paler ventrally.

Head: ( Figs 12 D, H , 14 D ) longer than wide and mainly smooth, with few distinct granules dorsally and on genae. Dorsal surface slightly flattened with distinct mediolongitudinal groove. Vertex rounded, posterolaterally also with a short groove. Eyes circular and strongly projecting hemispherically. Antennae distinctly projecting over front legs. Scapus slightly flattened dorsoventrally and oval in cross-section. Pedicellus short, knob-like and round in cross-section.

Thorax: ( Figs 12 D, H , 13 L , 14 D ) pronotum slightly shorter than head, slightly widening towards the posterior and sparsely granulose. Anterior margin strongly incurved with anterolateral angles extended and apically rounded. Base of anterolateral extensions with a minute peudoforamen. Median longitudinal groove starting anteriorly, not reaching posterior edge. Centrally with a short transverse impression not reaching lateral edges. Posterior margin rounded. Mesonotum distinctly longer than mesofemora, with scattered pale granules and parallel-sided. Metanotum with few pale granules, slightly longer than median segment, subapically with a median small hump, followed by a short transverse furrow. Prosternum with anterior margin straight, widening towards the posterior; posterior margin concave. Posternum with rough paired, almost circular sensory organs; longitudinally divided by a median furrow. Meso- and metasternum smooth.

Wings: ( Figs 12 D, H , 13 L ) tegmina absent. Alae small, not reaching median segment; costal area blackish with inner margin reddish; anal area bright red.

Legs: ( Fig. 12 A–C ) profemora shorter than mesonotum and half the pronotum combined; compressed and curved basally; all carinae present and unarmed; medioventral carina indistinct. Mesofemora shorter than mesonotum; ventral carinae indistinct. Metafemora slightly longer than profemora and unarmed. Protibiae slightly longer than profemora; subrectangular in cross-section and with outer ventral and dorsal carinae developed; carinae with small setae. Probasitarsus about as long as the following three tarsomeres combined. Mesotibiae about as long as mesofemora, with carinae as in protibiae, but with medioventral carinae present. Metatibiae distinctly longer than protibiae; carinae as in mesotibiae. Claws small when compared to body size; tarsomeres with a small posteromedian extension.

Abdomen: ( Figs 12 A–C, E–G , 13 M–N ) median segment wider than long, slightly trapezoidal and subapically with a faint transverse hump medially. All abdominal terga transverse with

24 few minute granules. Terga II–IX with faint median hump subapically, median hump more definite in terga VI–IX; tergum II about as long as median segment; III–VI about the same length; tergum VII slightly shorter than VI, trapezoidal, widening towards the posterior and with a small lobe dorsolaterally; VIII about the same length as VII, trapezoidal and narrowing towards the posterior; tergum IX distinctly shorter than VIII and tectiform. Anal segment about the same length as tergum IX, tectiform with mediolongitudinal carina and truncate apically. Abdominal sternum VII with definite praeopercular organ. Praeopercular organ broad at base, later tapering and resulting in a single spine. Subgenital plate reaching about apex of abdomen; apical half spoon-shaped and tapering posteriorly; posterior portion with a definite median longitudinal carina. Other abdominal sterna smooth with a small black marking posteromedially.

NYMPH ( Figs 13 A–B , 14 G )

Head orange with black postocular line. Antennae black and white. Body olivaceous brown with minute white spots; abdominal terga with anterolateral white markings; legs coloured as body with apical portion of femora orange and trochanters and coxae white.

EGG ( Fig. 13 O–Q )

Measurements (in mm). Length: 3.2; width: 2.2; height: 2.6.

Capsule oval, coloured brownish with darker markings and a reticulum; reticulum on capsule surface covered with minute stalked, cream granules. Polar area with dark marking; marking tapering towards and reaching and continuing on micropylar plate. Operculum oval and convex; coloured as capsule with several mushroom-like, stalked granules, more densely grouped in central portion. Micropylar plate positioned almost centrally on capsule, slightly displaced towards the polar area; almost circular, slightly darker than capsule; surface smooth; outer margin with few, minute whitish granules. Micropylar cup black and distinct, followed anteriorly by a definite mediolongitudinal carina.

BIOLOGY. Adults ( Fig. 14 A–F ) and nymphs ( Fig. 14 G ) were collected in tropical evergreen rainforest ( Fig. 14 H ), at low to medium altitude (250–800 m). The specimens were observed on lower vegetation. In captivity, eggs are dropped to the ground and a wide variety of alternative foodplants including Hypericum spp. ( Hypericaceae ) and different species of Rubus spp. ( Rosaceae ) were accepted.

When disturbed, they open their wings to show the bright red part of the alae as a defensive behaviour ( Fig. 13 G–H ).

DISTRIBUTION. Central Vietnam, provinces of Thua Thien-Hue and Da Nang ( Fig. 8 ) .

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Discussion

Together with the new taxa described herein, the total number of Necrosciinae in Vietnam now reaches 23 genera and 60 species. The two new genera are closely related and share a number of characters e.g. relatively stout body; subgenital plate in females relatively flat, more or less spoon-shaped with a longitudinal median carina in apical half; eggs with capsule more or less round to oval, capitulum rounded to conical, micropylar plate bearing a mediolongitudinal ridge; no specialised egg laying method with eggs dropped to the ground; males with a distinct, often specialised vomer. These common characters of both genera, also place them close to Oxyartes Stål, 1875 , Neohirasea Rehn, 1904 and a number of genera that were grouped in the tribe Neohiraseini Hennemann & Conle, 2008 by HENNEMANN & CONLE (2008) and HO et al. (2014). The latter tribe was originally included in the subfamily Lonchodinae following the generic classification at that time. Based on molecular analysis, BRADLER et al. (2014) transferred Neohirasea to the subfamily Necrosciinae , which comprises only the tribe Necrosciini . Consequently, the tribe Neohiraseini automatically became a junior synonym of Necrosciini . However, the morphological characters as listed above, as well as the phylogenetic trees provided by BRADLER et al. (2014) support a consistent clade within the Necrosciinae which includes the Neohiraseini sensu HENNEMANN & CONLE (2008) + Oxyartes and some further closely related taxa (e.g. Phaenopharos Kirby, 1904 , Paramenexenus Redtenbacker, 1908 , Phamartes Bresseel & Constant, 2013 and Pseudoparamenexenus Ho, 2016 ). Further study integrating molecular data of more taxa, morphological characters of adults and eggs and behavioural data needs to be conducted to assess the relevance of the resurrection of the tribe Neohiraseini within the Necrosciinae .

The presence of rough sensory areas on the prosternum and profurcasternum was considered an autapomorphy of Heteropterygidae by HENNEMANN et al. (2016). A similar structure has been observed for the first time in Necrosciinae , in Pterohirasea gen. nov. Further examination of putatively closely related genera, e.g. Neohirasea , Andropromachus , Spinohirasea and Brockphasma has shown that this character cannot be considered an autapomorphy of Neohiraseini sensu HENNEMANN & CONLE (2008) as it is not present in all genera and can even be present or absent in different species of the same genus as observed in Neohirasea . Additional study of those structures appears necessary to clarify their function and their relevance as a taxonomically useful character within Necrosciinae .

The sexual dimorphism in terms of size observed in Nuichua rabaeyae sp. nov. with the males being almost 50% shorter than females, is very strong compared to that in Pterohirasea nigrolineata sp. nov., with males only about 15% shorter than females. A hypothesis for this sexual dimorphism may be related to sexual selection in connection with the behaviour consisting, for the males reaching adulthood as first, to mate with and keep subadult females. This process may have induced the selection of the fastest growing males, i.e. those reaching maturity with the smallest size. This hypothesis is further supported by the fact that the male remains attached to the same female for all his life.

Figures

Fig. 8. Nuichua rabaeyae sp. nov. and Pterohirasea nigrolineata sp. nov., distribution map.

Fig. 9. Pterohirasea nigrolineata sp. nov., prosternal sensory organs.

Fig. 10. Pterohirasea nigrolineata sp. nov., holotype ♂. A, habitus, dorsal view. B, habitus, lateral view. C, habitus, ventral view. D, head and thorax, dorsal view. E, terminalia, dorsal view. F, terminalia ventral view. G, head and thorax, lateral view. H, terminalia, ventral view. I, terminalia, lateral view.

Fig. 11. Pterohirasea nigrolineata sp. nov., ♂ vomer. A, ventral view. B, detail of apex. C, lateral view.

Fig. 12. Pterohirasea nigrolineata sp. nov., paratype ♀. A, habitus, dorsal view. B, habitus, lateral view. C, habitus, ventral view. D, head and thorax, dorsal view. E, terminalia, dorsal view. F, terminalia, ventral view. G, terminalia, lateral view. H, head and thorax, lateral view.

Fig. 13. Pterohirasea nigrolineata sp. nov. A–N, captive reared, from Phong Dien VNMN Station (photographs by J. Constant). A–B, nymph. C, ♂, dorsal view. D, ♂, lateral view. E, ♂, head and thorax. F, ♂, dorsal view. G, ♂, lateral view. H, ♂, head and thorax. I, ♂, abdomen ventral view. J, ♀, dorsal view. K, ♀, lateral view. L, ♀, head and thorax dorsal view. M, ♀, abdomen ventral view. N, ♀, terminalia dorsal view. O, newborn nymph (photograph by T. Bollens). P–R, egg. P, lateral view. Q, dorsal view. R, operculum.

Fig. 14. Pterohirasea nigrolineata sp. nov., wild specimens and habitat in Bach Ma N.P. (photographs A–G by J. Constant, H by H.T. Pham). A–C, ♂, 12.VII.2011. D–F, ♀, 17.VII.2011. G, subadult nymph, 12.VII.2011. H, habitat in Bach Ma N.P, 12.VII.2011.