Ramulus pelengense Hennemann, Le Tirant & Purwanto, 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 : 76-79

Ramulus pelengense Hennemann, Le Tirant & Purwanto n. sp.

( Figs. 31 , 35G–H )

HT, ♂: O-Sulawesi, Prov. Sulawesi Tengah, Banggai-Inseln, Peleng Island , VII.2011 [ ZSMC, ex coll. FH] .

PT, 3 ♂♂: O-Sulawesi, Prov. Sulawesi Tengah, Banggai-Inseln, Peleng Island , VII.2011 [ FH, No’s 0790-1 to 3] .

PT, 1 ♀, 1 egg (ex ovipositor): O-Sulawesi, Prov. Sulawesi Tengah, Banggai-Inseln , W-Peleng Island, Buko-District, Tinanasu, XII.2011 [ ZSMC, ex coll. FH] .

PT, 12 ♂♂, 12 ♀♀, 3 eggs (ex ovipositor): O-Sulawesi, Prov. Sulawesi Tengah, Banggai-Inseln , W-Peleng Island, Buko Dis-trict, Tinanasu, XII.2011 [coll. FH, No’s 0790-4 to 26, E] .

PT, 10 ♂♂, 6 ♀♀: O-Sulawesi, Prov. Sulawesi Tengah, Banggai-Inseln , W-Peleng Island, Buko District , btw. Tatendeng village and Eben village 400-550 m, IX.2011 [ FH, No’s 0790-27 to 42] .

PT, 10 ♂♂, 10 ♀♀: O-Sulawesi, Prov. Sulawesi Tengah, Banggai-Inseln , W-Peleng Island, Buko District , btw. Tatendeng vil-lage and Eben village 400-550 m, IX.2011 [ IMQC] .

PT, ♂: Indonesia: Peleng Island , Tinagkung Utara, near Luksagu village, April 2017, leg. A. Brata, ex coll. Alexandre Banko [ IMQC] .

PT, 2 ♂♂, 2 ♀♀: E-Sulawesi, Prov. Sulawesi Tengah, Banggai-Islands , W-Peleng Island, Bulagi District , Alul village near Bulagi, VI.2020 [coll. EB].

Etymology: The name refers to the distribution of this new species, which is an endemic of Pulau Peleng, the largest of the Banggai Islands east of Sulawesi.

Differential diagnosis: Males of this new species are easily recognized by their distinctive colouration, being plain orange to yellowish ochraceous with only the median segment ( Fig. 31J ) and the head except for the frons contrasting black ( Fig. 31K–L ). Females are similar to those of R. togianense n. sp. from the Togian Islands and R. globosicaput (Brunner v. Wattenwyl, 1907) from Sulawesi but differ from both by the somewhat longer, apically pointed and tapered subgenital plate, which slightly projects over the apex of the abdomen ( Figs. 31D–F ), as well as the smooth posterodorsal carina of the profemora ( Fig. 31N ) and plain colouration. From the first species ♀♀ also differ by the lack of cephalic spines ( Figs. 31M–N ) and from the second species by larger size on average and their more slender and elongate appearance. The eggs differ from those of R. togianense n. sp. by the more elongate and slender shape, more prominent dorsal projection of the operculum and single very large pear-shaped posterolateral impression of the capsule ( Figs. 35G–H ). From those of R. globosicaput the eggs differ by the much more densely sculptured capsule surface, having the micropylar plate roughly in the mid of the dorsal egg surface (distinctly displaced towards the posterior in globosicaput), slightly shorter and less acute dorsal projection of the operculum and larger posterolateral impression oft he capsule ( Figs. 35G–H ).

Description: The description of the colouration of ♀♀ is described only from dried specimens and that of ♂♂ from pictures of live paratypes kindly forwarded to the author by Edy Bhaskara ( Indonesia).

♀ ( Figs. 31A–B ). Fairly large for the genus (body length including subgenital plate 131.0–148.0 mm), form slender, body surface entirely smooth, the head strongly globose and unarmed and the epiproct and subgenital plate somewhat elongated and projecting over apex of abdomen ( Figs. 31D–F ). Meso- and metatibiae sometimes with triangular lobe-like teeth. General colour various shades of dull ochre and drab to greyish mid brown, sometimes with a slight greenish hue. Genae usually dark brown to black in portion anterior to the eyes ( Figs. 31M–N ). Eyes dark reddish brown. Antennae with scapus and pedicellus coloured like body, the gradually becoming darker and almost black at the apex. Teeth and lobes of mesotibiae (if present) mid to dark brown.

Head: Strongly globose, sub-spherical, unarmed and just indistinctly longer than wide, broadest at eyes; vertex rounded and smooth ( Figs. 31M–N ). Frons with two very shallow widely C-shaped furrows. Eyes circular in outline, projecting almost hemispherically and their diameter contained about 2x in length of genae. Antennae 1.7x longer than head and pronotum combined, consisting of 24 antennomeres ( Fig. 31N ). Scapus strongly flattened dorsoventrally with the outer lateral margin strongly deflexed and rounded and the interior lateral margin gently deflexed, ovoid in dorsal aspect and much longer than wide. Pedicellus less than 1/3 the length of scapus, cylindrical. III much longer than pedicellus, the following antennomeres gradually decreasing in length, only the two terminal ones considerably longer than previous; terminal antennomere longest of all.

Thorax: Pronotum shorter and much narrower than head, the sub-anterior portion narrower than the widened posterior half; the latter with the lateral margins gently convex ( Figs. 31M–N ). Transverse median sulcus distinct, gently curved and expanding over entire width of segment. Meso- and metanotum with a very fine and indistinct longitudinal median line. Mesothorax about 2.75x longer than head and pronotum combined and about 1.5x longer than metanotum. Metanotum about 5.5x longer than wide.

Abdomen: Median segment quadrate and its length contained about 4.6x in that of metanotum. Abdomen excluding median segment considerably longer than head and complete thorax combined. All abdominal segment roughly uniform in with but sub-equal in length; II about 2.1x longer than median segment and 2.6x longer than wide; II–IV increasing in length, IV–VI almost equal in length and VII slightly shorter than previous; IV–VI on average 3.6x longer than wide. Preopercular organ merely represented by a distinctive black posteromedian marking on sternum VII ( Fig. 31F ). Tergum VIII about ¾ the length of VII, IX about ½ the length of VIII. Anal segment tectiform longitudinally, longer than IX and slightly narrowing towards the apex; posterior margin with a deep, triangular excavation and the posterolateral angles acutely triangular ( Fig. 31E ). Epiproct large, longer than wide with the apex acute and projecting noticeably beyond anal segment. Cerci very small, tapered towards the tip and slightly in-curving. Subgenital plate elongate, just slightly convex in post-median portion ( Fig. 31D ), slightly keeled longitudinally on apical half and with the apex fairly acute, gently down-curving and ± reaching tip of epiproct ( Figs. 31D–F ).

Legs: All long and slender with all carinae covered by fine, black setae. Mesofemora occasionally with 3–4 small denticles in apical half of posterodorsal carina. Medioventral carina of meso- and metafemora well defined and with an obtuse tooth sub-apically ( Fig. 31O ). Mesotibiae either entire unarmed, with 1–2 teeth or triangular lobes in basal half of posterodorsal carina and/or sometimes with 1–2 teeth or triangular lobes in basal half of posteroventral carina. Metatibiae either unarmed or with a single teeth or triangular lobe ¼ off the base on posterodorsal carina. The posterodorsal carina of both the meso- and metatibiae with some minute teeth in apical half, the metatibiae with further teeth on two outer ventral carinae. Basitarsi very long, slender and notably longer than combined length of remaining tarsomeres.

♂ ( Fig. 31C ). Of moderate size for the genus (body length 93.0–108.0 mm), very slender and with a globose head. General colour of body dull yellow with a slight greenish wash, the abdomen somewhat darker and with a more orange hue. Coxae more greenish. Head black except for a yellowish frons ( Figs. 31K–L ); eyes orange. Antennae black except for scapus and pedicellus. Most of median segment black ( Fig. 31J ). Legs dull orange, tarsi dark greenish grey. All dried specimens at hand are more or less plain orange-brown.

Head: Shape generally as in ♀♀, but eyes much larger, projecting more than hemispherically and their diameter contained only 1.5x in length of genae. Between the eyes with two very shallow humps and on frons just behind the bases of the antennae with two shallow impressions ( Figs. 31K–L ). Antennae with 22 antennomeres, all more elongate than in ♀♀ and antennae about as long as head, pro- and mesothorax combined. Scapus 2.7x longer than wide, slightly narrowing towards the base and gently compressed dorsoventrally. Pedicellus sub-cylindrical a somewhat less than ½ the length of scapus. III very elongate and about as long as the two preceding segments combined, following antennomeres gradually decreasing in length; only terminal antennomere longer than preceding.

Thorax: Pronotum as in ♀♀, shorter and notably narrower than head ( Fig. 31L ). The tranverse median sulcus however much more pronounced and not expanding entire width of segment. Meso- and metanotum with a very fine and indistinct longitudinal median line. Mesothorax about 4x longer than head and probotum combined and 1.4x longer than metanotum; gently widened anteriorly and posteriorly.

Abdomen: Median segment somewhat trapezoidal with anterior margin narrower than posterior margin, a little longer than wide ( Fig. 31J ) and its length contained almost 8x in that of metanotum. Abdomen excluding median segment slightly longer than head and complete thorax combined. Segment II about 3.3x longer than median segment, III–V almost equal in length and somewhat longer than II, VI and VII notably decreasing in length with VII about ¾ the length of II; on average III–V 6x longer than wide. Terga II–VII all with a very fine longitudinal median carina. Tergum VIII about ½ the length of VII and slightly widening towards posterior; IX shorter and somewhat broader than all preceding segment. Anal segment almost as long as VIII and IX combined, split longitudinally ( Fig. 31H ) and strongly tectiform; the hemi-terga in lateral aspect with the apical 1/3 first constricted than widened, rounded dorsally and the apical portion roundly triangular ( Fig. 31G ) and interiorly armed with several small, blackish teeth ( Fig. 31H ). Cerci slender, gently in-curving and with the apex obtusely rounded. Poculum very small, scoop-shaped, bluntly keeled longitudinally and with the posterior margin somewhat labiate; reaching to posterior margin of tergum IX ( Fig. 31G ).

Legs: All very long and very slender; unarmed except for a single, small and obtuse sub-apical tooth on medioventral carina of meso- and metafemora and a few minute denticles in apical portion of all outer carinae of metatibiae. Basitarsi all very much elongated and slender, probasitarsus 2x longer than combined length of remaining tarsomeres, meso- and metabasitarsus slightly less than 2x the length of remaining tarsomeres combined.

Variability: Females show considerable variability in the armature of the meso- and metatibiae, which is described above. No noteworthy variability is seen in ♂♂.

Eggs (Figs.. 35G–H): Fairly large, moderately elongate and about 3.3x longer than high, strongly laterally flattened and much higher than wide. Capsule in lateral aspect slightly widened in the posterior half with polar area prominently indented, in dorsal aspect somewhat widened anteriorly. Entire capsule surface uneven, very densely and minutely granulose and all over irregularly covered with small, peg-like tubercles. The lateral surfaces with a large, pear-shaped impressed area in posterior portion and with about five smaller, rounded impression that are arranged in an almost median longitudinal line to form an indicated furrow. Dorsal and ventral surfaces with a very blunt and rounded medio-longitudinal bulge, which is on both sides marked by a slender and shallow furrow; the dorsal bulge interrupted at the slightly inserted micropylar plate and on each side with a distinct impression close to polar end of capsule. Micropylar plate fairly large and bilobed, consisting of two roughly oval portions, that expand almost half way over the lateral surfaces. Micropylar cup a small, knob-like swelling that is placed in the posteromedian gap of the plate. Median line short and indistinct. Operculum oval and with a raised, crenulate outer rim, that is protruded dorsally to form an obtuse, tooth like shape. Colour fairly plain greyish ochre. The outer margin of the micropylar plate broadly marked with chestnut brown and the outer portions in the impressed area of the lateral surfaces blackish. Measurements [mm]: Length (including operculum) 7.8, length 7.0, width 1.3, height 2.1, length of micropylar plate 2.2.

Comments: This species occurs in lowland habitats in Peleng and is known to feed on the Balanda tree ( Macaranga sp. , Euphorbiaceae ). But since member of the genus Ramulus are often rather polyphagous it is likely that also other plants are among the natural host plants of R. pelengense n. sp.. In captivity in Indonesia guava ( Psidium guajava , Myrtaceae ) is readily accepted as an alternative food plant.

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

Figures

FIGURE 31. Ramulus pelengense n. sp.: A. ♀ (PT), dorso-lateral view [coll. FH, No. 0790-5]; B. ♀ (PT), dorso-lateral view [coll. FH, No. 0790-6]; C. ♂ (PT), dorso-lateral view [coll. FH, No. 0790-6]; D. Lateral view of terminal abdominal segments of ♀ (PT) [coll. FH, No. 0790-4]; E. Dorsal view of terminal abdominal segments of ♀ (PT) [coll. FH, No. 0790-4]; F. Ventral view of terminal abdominal segments of ♀ (PT) [coll. FH, No. 0790-4]; G. Lateral view of terminal abdominal segments of ♂ (PT) [coll. FH, No. 0790-3]; H. Dorsal view of terminal abdominal segments of ♂ (PT) [coll. FH, No. 0790-3]; J. Dorsal view of median segment (= abdominal tergum I) of ♂ (HT) [ZSMC];K. Head and prothorax of ♀ (HT) seen dorso-laterally [ZSMC]; L. Head and prothorax of ♂ (HT) in dorsal view [ZSMC];M. Head and prothorax of ♀ (PT) seen dorso-laterally [coll. FH, No. 0790-5]; N. Head with antennae and prothorax of ♀ (PT) seen dorso-laterally [coll. FH, No. 0790-29]; O. Apex of right mesofemur of ♀ (PT) seen intero-laterally [coll. FH, No. 0790-4].

FIGURE 35. Ramulus spp., eggs: A. R. globosicaput (Brunner v. Wattenwyl, 1907), dorsal view [coll. FH, No. 0303-E]; B. R. globosicaput (Brunner v. Wattenwyl, 1907), lateral view [coll. FH, No. 0303-E]; C. R. torajanus n. sp., dorsal view (PT) [coll. FH, No. 1064-E]; D. R. torajanus n. sp., lateral view (PT) [coll. FH, No. 1064-E]; E. R. togianense n. sp., dorsal view (PT) [coll. FH, No. 0733-E]; F. R. togianense n. sp., lateral view (PT) [coll. FH, No. 0733-E]; G. R. pelengense n. sp., dorsal view (PT) [coll. FH, No. 0790-E]; H. R. pelengense n. sp., lateral view (PT) [coll. FH, No. 0790-E];