Ramulus extensus, 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 : 70-72

Ramulus extensus n. sp.

( Fig. 28 )

Baculum globosicaput, Günther, 1938: 60 .

HT, ♂: Sarasin 28.I.–1. II.1895, Luwu, Flachland, Goran-Djaladja, Centr. - Cel.; Baculum globosicaput Br. v. W. Günther det. [ NHMB]

Etymology: The name ( extensus lat. = extended, elongated) refers to the strongly elongated terminal two abdominal terga of ♂♂ of this new species ( Figs. 28B–C ).

Differential diagnosis: Males, the only sex known, differ from all other species so far known from Sulawesi by the enlarged terminal three abdominal terga which together are equal in length to abdominal segments II and III combined ( Figs. 28B–C ); notably shorter than II and III combined in all other Sulawesian species). Abdominal tergum IX is almost 2x longer than high (at best slightly longer than high in the other species) and the anal segment is about 3x longer than high (at best 2.2x longer than high in the other species).

Description: The following description is based on the unique holotype, which has provisionally been preserved in spirits. Thus, the specimen is with great certainty discoloured and the description of the colours must be taken with caution. The specimen lacks the tips of both antennae and the left fore leg.

♂ ( Fig. 28A ). Of moderate size (body length 106.0 mm) for the genus, very thin and stick-like with a strongly globose head and characteristically elongated abdominal terga IX and X. General colour uniformly buff (believed to be orange when alive), the terminal three abdominal segments reddish brown with the apical portion of the anal segment ochre. Antennae blackish brown with the two basal segments dark brown. Cerci ochre. Eyes yellowish grey.

Head: Fairly large, strongly globose, slightly longer than wide, narrowed posteriorly, smooth and broadest just behind the eyes ( Fig. 28D ). Between the bases of the antennae with a slight impression and between the eyes with two very slightly swollen, oval areas. Eyes very large, projecting more than hemispherically and their diameter contained about 1.9x in length of genae. Antennae almost reaching apex of profemora and laid back reaching at least half way along mesonotum (broken in the holotype). Scapus compressed dorsoventrally, narrowed towards the base and about 2x longer than wide. Pedicellus cylindrical and roughly half the length of scapus. Antennomere III longer than scapus and pedicellus combined.

Thorax: Pronotum shorter and notably narrower than head, roundly rectangular in outline with the posterior portion slightly expanded laterally and wider than anterior portion ( Fig. 28D ). Transverse median sulcus distinctly impressed, weakly W-shaped and reaching to lateral margins of segment. Mesothorax very elongate and 11.8x longer than prothorax but just 1.26x longer than metanotum; very gently widened posteriorly. Metathorax somewhat constricted medially. Meso- and metanotrum with a very faint medio-longitudinal line.

Abdomen: Median segment slightly trapezoidal, just slightly longer than wide and only 0.12x the length of metanotum. Segment II about 3x longer than median segment. II–V almost uniform in length, VI and VII slightly decreasing in length with VII only about 2/3 the length of II–V; all uniform in width but VII very weakly widening towards the posterior. II–V almost 5x and VII only 3.3x longer than wide. Terga VIII–X much broader than all preceding with VIII widest and 2x wider than preceding segmens; VIII–X together equal to combined length of II and III. VIII about 2/3 the length of VII, swollen, strongly widening towards the posterior, trapezoidal in dorsal aspect and with the lateral margins somewhat deflexed. IX distinctly longer than VIII, 2x longer than high and gradually narrowed towards the posterior. Terga VIII and IX both with a fairly distinct medio-longitudinal carina. Anal segment 1.2x longer than IX, split longitudinally, strongly tectiform and 3x longer than high; the hemi-terga in lateral aspect with the apical one third gradually narrowing, basically triangular in outline and rounded at the apex ( Fig. 28B ), interiorly they are armed with several small, blackish brown teeth ( Fig. 28C ). Cerci slender, gently in-curving and narrowing towards a slightly club-shaped apex. Poculum very small, scoop-shaped, obtusely keeled longitudinally and with the posterior margin somewhat labiate; not reaching posterior margin of tergum IX.

Legs: All long and very slender and entirely unarmed. Profemora slightly longer than head, pro-, meso- and metanotum combined, mesofemora somewhat longer than head, pro- and mesothorax combined and metafemora reaching half way along abdominal segment VII. All basitrarsus roughly 2x longer than combined length of remaining tarsomeres.

Comments: The unique ♂ holotype from Boran-Djaladja in the collection of NHMB was erroneously listed as R. golobosicaput by Günther (1938: 60). Comparison with the specimen has show the specimen to represent a distinct species that is well characterized by the notably enlarged three terminal abdominal segment and strongly elongated two terminal abdominal terga. Female and egg unknown.

Distribution: So far only known from Djaladja in the Luwu Regency of South Sulawesi.

Figures

FIGURE 28. Ramulus extensus n. sp. ♂, holotype [NHMB]: A. Habitus, dorsal view; B. Terminal abdominal segments seen laterally; C. Terminal abdominal segments seen dorsally; D. Head and orothorax in dorsal aspect.