Pylaemenes pleurospinosus Hennemann & Le Tirant, 2021

Hennemann, Frank H., 2021, Stick insects of Sulawesi, Peleng and the Sula Islands, Indonesia- a review including checklists of species and descriptions of new taxa (Insecta: Phasmatodea), Zootaxa 5073 (1), pp. 1-189 : 25-26

Pylaemenes pleurospinosus Hennemann & Le Tirant n. sp.

( Fig. 11 )

HT, ♀: Indonesia, Peleng Island , Tinangkung Utara District, near Luksagu village ca. 60 m elev., 1°17’S 123°25.4’ E, VII.2012 [ IMQC, ex coll. FH, No. 1147-1] .

PT, ♀ (n5): Indonesia, Peleng Island , Tinangkung Utara District, near Luksagu village ca. 60 m elev., 1°17’S 123°25.4’ E, VII.2012 [coll. FH, No. 1147-2] .

Etymology: The name refers to the prominent and long supra-coxal spine of the mesopleurae, which readily distinguishes this new species from all other Wallacean representatives of the genus.

Differential diagnosis: Very similar to the type-species P. coronatus ( Haan, 1842) but at once differing from this and all other species of Pylaemenes so far known to occur throughout Wallacea by the presence of a prominent supracoxal spine on the mesopleurae ( Figs. 11F–G ). Females, the only sex known furthermore differ from the other Wallacean species by having the supra-coxal spine of the metapleurae notably more prominent and the mesonotum relatively more slender with the lateral margins very gently concave and at the anterolateral angle armed with a prominent, slender laterad directed antero-lateral mesonotal spine ( Fig. 11G ).

Description: The description is based exclusively on the unique holotype. The nomenclature used for body armature follows that used for the Heteropteryginae Kirby, 1896 by Hennemann et al. (2016) and that for the cephalic armature follows the nomenclature used for the genus Orestes Redtenbacher, 1906 by Bresseel & Constant (2018: 6, fig. 1).

♀ ( Fig. 11 ). Fairly large (body length 59.0 mm) and moderately stocky for the genus with strongly developed cephalic and body armature and prominent supracoxal spines on the meso- and metapleurae. As typical for the genus, entire dorsal body surface tectinate longitudinally. General colour of the HT greyish and ochraceous mid brown, the lateral margins of the thoracic terga and the base of the large supracoxal spines with a slight pale green wash. All major spines tipped with dull ochre. Abdominal tergum VI with two velvety black, roundly angular central markings. Eyes dull orange.

Head: Slightly longer than wide with the vertex strongly raised and posteriorly somewhat extending over anterior portion of pronotum, the genae very slightly widening towards the posterior. Frons with a very prominent and long, somewhat anteriad directed pair of supra-antennals, the anterior and posterior supra-occipitals much smaller and bluntly rounded; the posterior pair smaller than the anterior pair. Vertex with two converging cristate and unevenly tri-tuberculate ridges, each of which terminate in a prominent, conical but blunt anterior coronal spine. The supra-orbitals large, similar in size to anterior-coronals and positioned close to the aforementioned ridge ( Fig. 11F ). The central coronal prominent and bluntly conical; on each side a much smaller, obtuse lateral coronal tubercle. The two posterior coronals prominent, conical and similar in size to the anterior coronals; the lateral coronals at posterior margin of head notably smaller than the median pair. Postocular ridge very prominent, unevenly and obtusely crenulate and posteriorly terminating in a blunt tubercle. Eyes very small, projecting sub-spherically and their diameter contained about 3.2x in length of genae ( Fig. 11G ). Antennae consisting of 20 segments and notably projecting over apex of protarsi. Scapus longer than wide, somewhat widening towards the base and the outer margin armed with a fairly acute, lateral directed spine at the base and a more blunt, anteriad directed spine at the apex ( Fig. 11F ). Antennomere III distinctly elongated and longer than pedicellus and all following antennomeres.

Thorax: Pronotum notably wider and slightly longer than head, roughly quadrate in shape with lateral margins somewhat concave ( Fig. 11G ). The transverse median sulcus strongly impressed, straight and short. In front of the sulcus a very strong pair of bluntly conical pre-median pronotals and just behind it a small but fairly acute pair of post-medial pronotals. The anterior-mesal pronotals small, the inter-posterior pronotals moderate and rather obtuse. The antero and postero-lateral pronotals at the outer angles of the pronotum weakly developed and blunt. Sensory areas of the prosternum and profurcasternum well developed. Mesothorax moderately slender and 3.5x longer than pronotum, the mesonotum about 2.7x longer than wide and roughly rectangular with the lateral margins very weakly concave ( Fig. 11G ). Dorsal surface with a prominent longitudinal median carina, which bears a small pair of closely placed pre-median tubercles and a very small pair of post-median tubercles ( Fig. 11F ). The anterior-mesal pronotal spines at the raised anterior margin very prominent, upright and pointed. The posterior-mesal pronotals notably smaller than the anterior ones. Surface otherwise very spasely and obtusely tuberclose. Lateral margins distinct and set with about six spiniform tubercles, which notably decrease in size towards the posterior; the antero-lateral mesonotal very prominent, long and pointed. Mesopleurae with a longitudinal row of about five blunt tubercles and two supra-coxal spines; the posterior spine very prominent, slender, acutely pointed and strongly projecting laterally ( Fig. 11G ). Metanotum less than half the length of mesonotum, about 1.4x longer than wide and with lateral margins notably concave; sculptured like mesonotum but only with a fairly small pair of post-median tubercles and the lateral margins with five equally sized blunt tubercles. Metapleurae set with three spiniform lateral tubercles and the same two supra-coxals seen on the mesopleurae; the posterior supra-coxal however even more prominent, comparatively stronger and laterally projecting by almost half the width of metanotum ( Figs. 11A, C ). Meso- and metasternum with a very faint longutudinal median carina and set with a few indistinct and low paired tubercles ( Fig. 11C ).

Abdomen: Median segment transverse with anterior margin widely rounded; the median keel forming an obtuse swelling anteriorly and with two small tubercles posteriorly. Segments IIII–III widening, IV widest, V–VI narrowing, VII narrowest, VIII widening; all transverse and rectangular in outline, IV about 2.6x wider than long. II–VIII with a prominent, tectinate median keel, which is most prominent on V and bears a small pair of median tubercles; near posterior margin with posteromedian pair of spines which is most indistinct on II and most prominent on V. II–VIII with 3–4 small tubercles along lateral margins and each armed with a prominent, straight, lateral directed and acutely pointed posterolateral spine. Median carina on tergum IX strongly raised and forming a large, irregularly shaped crista that posteriorly projects over the anterior portion of the anal segment; lateral margins somewhat deflexed and broadly triangular in outline. Sterna II–VII weakly tectinate longitudinally and with a few scattered, low tubercles. Preopercular organ on sternum VII formed by an obtuse, transverse, scale-like expansion of the posterior margin. Anal segment much narrower than all preceding terga, strongly narrowing towards the posterior and with a blunt longitudinal median carina; the lateral margins with a bluntly triangular expansion in anterior half and the apex bifid with a distinct triangular median excavation ( Fig. 11D ). Epiproct small, scale-like and concealed under anal segment ( Fig. 11E ). Subgenital plate moderately convex, carinate medio-longitudinally, not reaching apex of anal segment and the posterior margin broadly rounded ( Fig. 11E ); the surface unevenly rugulose and with a single spiniform central tubercle on each lateral surface.

Legs: All moderately long and stocky, all tibiae unarmed. Profemora with a single, blunt sub-apical tooth on posteroventral carina, otherwise unarmed. Meso- and metafemora with a two sub-apical teeth on the two outer ventral carinae of which the apical one is notably larger; furthermore with two blunt teeth in basal half of posterodorsal carina.

Comments: Males and eggs unknown. The immature ♀ paratype has a body length of 42.0 mm and well ex-hibits the characteristic supracoxal spines of this species.

Distribution: Apparently endemic to the Island of Peleng, the largest of the Banggai Islands positioned east of Sulawesi.

Figures

FIGURE 11. Pylaemenes pleurospinosus n. sp. ♀, holotype [IMQC]: A. Habitus, dorsal view; B. Habitus lateral view; C. Habitus ventral view; D. Terminal abdominal segments in dorsal view; E. Terminal abdominal segments in ventral view; F. Head, pro- and mesothorax in dorso-lateral view; G. Head, pro- and mesothorax in dorsal view.