Hemiplasta parva, Hennemann, 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 : 141-142

Hemiplasta parva n. sp.

( Fig. 56 )

HT, ♂: Indonesien, Zentral Sulawesi , Prov. Sulawesi Tengah, Palolo District, Palu , VIII.2012 [ MNHU, ex coll. FH No. 0824- 1]

Etymology: The name (parvus lat. = small) refers to the small size of this new species.

Differential diagnosis: Males of this new species, the only sex known, differ from all other known ♂♂ by the smaller size. The dark brown colour makes them resemble H. nigra (Henneman, 1998) n. comb. but the slender three terminal abdominal segments, that are not notably wider than the preceding segments ( Fig. 56E ), and somewhat shorter alae which only reach about half way along abdominal segment VI (at least to posterior margin of VI in nigra ) readily distinguish this new species. In relation to the body length the still unknown ♂♂ of H. parva Günther, 1938 may be similarly small like this new species. However, in aspect of the very similar head and thoracic morphology frequently seen in the two sexes of an individual species, it is very unlikely that this new species is the ♂ of H. aptera ( Fig. 50E ). The sculpturing of the mesonotum of the ♀ of H. aptera is different, the head is much more elongate ( Fig. 50F ) and the fact that it is completely apterous and has a median segment that is slightly shorter than the metanotum rather suggests the corresponding ♂ to be brachypterous or at least have shorter wings than H. parva n. sp..

Description: ♂ ( Figs. 56A–B ). Small (body length 44.7 mm) and fairly stocky for the genus, with well developed ale (22.0 mm) that reach about half way along abdominal segment VI and very long, club-shaped cerci. General colour plain dark brown with a very slight greenish wash on the thoracic segments. Abdomianl terga II–VII with two faint black spots just before the middle, the sterna with two faint block spots in posterior half. Tegmina and costal region of alae plain dark brown, the latter with the base ochre; anal fan of alae transulcent grey with a slight ochre hue. Basal one third of profemora very drak green, that of the meso- and metafemora apple green. Tibiae with a slight orange wash except for the basal and apical portion. Eyes mid brown, antennae very dark reddish brown.

Head (fFg. 56C): Fairly large, rounded subquadrate in dorsal aspect, the genae slightly convex and broadest just behind the eyes; vertex very gently rounded, smooth and with three longitudinal indentions at posterior margin. Frons with two shallow raised areas between the eyes and a very small, V-shaped impression betwenn bases of antennae. Eyes very large and projecting sub-spherically, their diameter contained less than 1.3x in length of genae. Scapus compressed dorsoventrally, rectangular in dorsal aspect and a little longer thna wide; pedicellus cylindrical. Antennae raeching to posterior margin of abdominal segment VI.

Thorax: Pronotum almost as long but notably narrower than head and narrowing towards the posterior with the lateral margins weakly concave; distinctly longer than wide ( Fig. 56C ). Longitudinal median line impressed over entire length, the transverse median sulcus somewhat displaced towards the anterior, very widely V-shaped and expanding entire width of segment; surface very weakly uneven with some indicated granules. Mesothorax elongate and about 3.8x longer than pronotum. Mesonotum weakly tectinate longitudinally with a fine but acute mediolongitudinal carina, surface otherwise densely set with roundes, somewhat node-like granules; the granules becoming fewer towards the posterior and post-medially with a smooth, oval area laterally. Parallel to lateral margins with a granulose carina. Mesosternum weakly tectinate longitudinally and sparsely granulose; metasternum smooth. The pleurae very weakly and sparingly set with minute granules. Tegmina roundly rectangular in outline with the central hump very shallow. Alae reaching about half way along abdominal segment VI.

Abdomen: Segments II–VII uniform in width, all longer than wide with II–IV equal in length and V–VII gradually decreasing in length; VII only about 1.6x longer than wide and about 3/5 the length of II–IV. Tergum VIII about ¾ the length of VII and just very weakly widening towards the posterior ( Fig. 56E ), the posterior margin deeply concave and with a roundly triangular membranous are that allows to culr up the terminal two abdominal segments. IX about 1.4x longer and notably higher than VIII, the anterior margin concave and with a membranous area; rectangular in dorsal aspect. Anal segment obtusely tectinate, about 2/3 the length of IX with lateral margins almost parallel-sided; the posterior margin with a distinct triangular excavation ( Fig. 56E ) and the outer angles obtusely rounded and swollen ( Fig. 56G ) with the intero-ventral surface set with minute denticles ( Fig. 56G ). Epiproct very small, shield-shaped and almost semi-circular. Vomer roughly triangular in shape with a short but strongly up-curving terminal hook. Cerci very elongate, slender, gently in-curving and with the apex swollen and club-shaped; about as long as anal segment (figs. 56E–F). Phallus a long and slender, filiform organ that is gently arched towards the left and distinctly projects over the upper margin of the poculum ( Fig. 56G ). Sternum IX bulgy with the posterior margin labiate and distinctly expanded towards the posterior in the median portion. Poculum cup-shaped, somewhat compressed laterally and with the posterior portion narrowed; the lateral margins just weakly e,arginated ( Fig. 56D ).

Legs: All long, slender and entirely unarmed; only medioventral carina of meso- and metafemora with a very indistinct and small sub-apical swelling. Profemora almost as long as head, pro- and mesothorax combined, metafemora reaching to posterior margin of abdominal segment V and metatibiae projecting slightly beyond tip of abdomen. Tarsi all long and slender with the basitarsi longer than the following three tarsomeres combined.

Comments: So far only known from the unique ♂ holotype. Female and egg unknown.

Distribution: Central Sulawesi, Prov. Sulawesi Tengah (Palu).

Figures

FIGURE 50. Hemiplasta spp., ♀♀: A. H. sarasinorum Günther, 1938 ♀ (HT), dorso-lateral view [NHMB]; B. Close up of metathorax of ♀ (HT) of H. sarasinorum Günther, 1938, showing tegmina and abbreviated alae [NHMB]; C. Terminal abdominal segments of ♀ (HT) of H. sarasinorum Günther, 1938, seen laterally [NHMB]; D. Terminal abdominal segments of ♀ (HT) of H. sarasinorum Günther, 1938, seen dorsally [NHMB]; E. H. aptera Günther, 1938 ♀ (HT), lateral view [NHMB]; F. Head and prothorax of ♀ (HT) of H. aptera Günther, 1938, seen laterally [NHMB]; G. Terminal abdominal segments of ♀ (HT) of H. aptera Günther, 1938, seen laterally [NHMB].

FIGURE 56. Hemiplasta parva n. sp. ♂, holotype [MNHU]: A. Habitus, dorso-lateral view; B. Habitus, dorsal view; C. Head and prothorax seen dorsally; D. Terminal abdominal segments in lateral aspect; E. Terminal abdominal segments in dorsal aspect; F. Terminal abdominal segments in ventral aspect; G. Terminal two abdominal segments of ♂ in ventro-caudal aspect, showing the cerci and elongate tube-like phallus.