Phyllium (Phyllium) riedeli, Kamp & Hennemann, 2014

Kamp, Thomas Van De & Hennemann, Frank H., 2014, A tiny new species of leaf insect (Phasmatodea, Phylliidae) from New Guinea, Zootaxa 3869 (4), pp. 397-408 : 398-404

Phyllium (Phyllium) riedeli n. sp.

HT, ♀: Papua Province, Indonesia, S03° 57.161´E138° 57.357´, 1875m, Nothofagus forest, 11.XII.2010, beaten ( SMNK) .

PT, 4 eggs: laid by the HT in captivity ( SMNK) .

Differentiation. The ♀ of Ph. (Ph.) riedeli n. sp. is the smallest adult ♀ known in the genus so far, with a body length of only 56.3 mm. The shape of the abdomen, which is gradually tapered from segment IV onwards, shape of the profemora, lack of exterior lobes on the tibiae and ventrally unarmed antennomeres clearly place this new species in the subgenus Phyllium (Phyllium) .

Since Ph. (Ph.) riedeli n. sp. is from New Guinea, it is most certainly endemic to that island and hence unlikely to occur elsewhere, especially throughout the Wallacea. This is also the case for the other four New Guinean members of the subgenus i.e. Ph. (Ph.) caudatum Redtenbacher, 1906 , Ph. (Ph.) elegans Grösser 1991 , Ph. (Ph.) telnovi Brock, 2014 and Ph. (Ph.) zomproi Grösser, 2001 . An exception is Ph. (Ph.) caudatum , which also occurs in New Britain and the Solomon Islands. Consequently, Ph. (Ph.) riedeli n. sp. is here only differentiated from the species occurring in New Guinea.

The most closely related and similar species appears to be Ph. (Ph.) caudatum . From this species ♀ of Ph. (Ph.) riedeli n. sp. can be distinguished by: the smaller size, less granulose head capsule, less spiny mesothorax, broader and apically rounded tegmina, shape of the subgenital plate, smaller teeth of the interior lobe of the profemora, more slender and less expanded exterior lobe of the profemora and smaller interior lobes of the protibiae.

From Ph. (Ph.) zomproi ♀ differ by: the much smaller size, gradually tapered abdominal segment VI–X, presence of a distinct posteromedian tubercle on the head, lower number of teeth on the pars stridens of antennomere III (25 in Ph. riedeli n. sp., 48–50 in Ph. zomproi ), less spiny mesothorax, shape of the subgenital plate, much more slender and less rounded interior and exterior lobes of the profemora and shorter but more distinctly rounded interior lobe of the protibiae. From Ph. (Ph.) elegans ♀ differ by: the much smaller size, much more slender abdomen, which is gradually tapered from segment VI onwards with segments VII and VIII not lobed, shorter and broader apically rounded tegmina, shape of the profemora and shape of the subgenital plate.

Ph. (Ph.) telnovi seems to be closely related but is only known from the ♂. However, with a body length of 50 mm the ♂ of this species is by far too large to represent the opposite sex of Ph. (Ph.) riedeli n. sp.. Also, the distinct armature of the interior lobe of the profemora and fairly large spines of the mesothorax clearly show it to be distinct.

Ph. (Ph.) riedeli n. sp. may also be distinguished from all other species of Phyllium by the unique shape of the eggs.

Etymology. The species is dedicated to the entomologist and weevil specialist Alexander Riedel.

Description. The description of the colouration is based on the appearance of the HT immediately after its death. The eggs used for the description were laid by the HT in captivity.

♀ ( Fig. 1 ). Small-sized for the subgenus (body length 56.3 mm) with a moderately broad abdomen (maximum width 23.0 mm) gradually tapered towards the apex from segment IV onwards. Exterior lobes of the profemora ( Fig. 4C ) narrow and rounded, interior lobes dentate and roundly triangular.

Colouration. Living HT mostly green with pale dark red speckles on tegmina. Ventral body surface generally darker. Alae (a) transparent ( Fig. 3E ). Antennae (from antennomere II onwards), tips of labial and maxillary palpi and tubercle (pmt) on posteromedian head capsule pale dark red ( Fig. 2D ). Compound eyes with reddish/dark brown pattern ( Fig. 2A ). Mesopleurae (mp) pale dark red, anterior-most spiniform tubercles of meso-praescutum (mps) dark green ( Fig. 3C ). Fine light green median line extending from posterior abdominal segment II to VIII. Distinct white spot with brown frame on the posteromedian ventral abdominal segment I. Similar, but smaller triangular-shaped spots at segments V and VI. Large light spots in the center of each side of abdominal segment V, best visible ventrally but also dorsally below the tegmina. Abdomen with a thin, brownish frame extending from abdominal segment IV towards the apex. Segment IX dorsally with dark red spots extending to the lateral margins. Ventral coxal surfaces green ( Fig. 4B ), dorsal surface of procoxae and protrochanters brown. Interior lobes (fil) of profemora ( Fig. 4C ) with yellowish/brownish-red pattern at dentate side. Dorsal part of the exterior lobes (fel) of profemora brownish-red (coxal margin) to green (tibial margin). Protibial interior lobes (til) brownish-red with three yellowish lines perpendicular to the tibia ( Fig. 4C ). Propraetarsi pale dark red. Exterior lobes of mesofemora with a brownish spot on the proximal margin and three pale dark red spots of different sizes distally (proximodistal sequence: large, small, medium). Interior lobes of mesofemora exhibit a similar colour pattern as the profemora. Mesotibiae with a pale dark red spot near the proximodorsal margin. Colour pattern of metafemora very similar to mesofemora, but with a larger gap between the second and third distal spot of the exterior lobe. Metatibiae similar coloured to mesotibiae, but with reddish distal margin. Metatarsomeres I to IV reddish.

Morphology. Head capsule ( Figs 2A,B ) broad with convex cheeks. Vertex smooth except for several granules, a distinct posteromedian tubercle (pmt) and small protuberances (pt) between compound eyes and antennal bases. Antennae ( Figs 2C,D ) moderately slender and elongate (3.4 mm), longer than postocular section of head capsule (2.7 mm) and consisting of nine segments. Apical antennomere (IX) cylindrical with rounded apex, about 2x longer than wide and ± 2x as long as VIII. Stridulatory file (pars stridens) on antennomere III with 25, stridulatory ridge (plectron) with 19 teeth ( Fig. 3E ). Pronotum ( Fig. 3A ) roughly squarish with slightly concave anterior margin and moderately convex lateral and posterior margins. Anterior margin of pronotum thickened, in particular around the openings of the prothoracic defensive glands. Prosternum smooth, except for some minor granules ( Fig. 3B ). Meso-praescutum (mps) almost as long as wide (length-width ratio 1.1: 1), gently narrowing towards posterior ( Fig. 3C ). Lateral margins armed with few spiniform tubercles of variable sizes, the larger ones located near the anterior margin. Disc with 8 ± prominent tubercles. Mesopleurae (mp) strongly and gradually diverging; their lateral margins with five distinct spiniform tubercles ( Fig. 3C ). Anterior mesosternum sparsely and irregularly granulose ( Fig. 3D ). Tegmina (length 31.2 mm, max. width 12.3 mm) extending over 1/3 of abdominal segment VII. Alae (al) rudimentary (length 6.7 mm, max. width 2.6 mm), roughly 1/5 the length of tegmina ( Fig. 3E ). Abdominal segments II–IV gradually widened, IV widest segment, first 1/3 gradually diverging. V–X gradually tapering towards the apex. Anal segment (X) ± as long as wide with rounded apex. Subgenital plate (sp) rather short, slightly projecting over the posterior margin of abdominal segment IX ( Fig. 4A ). Profemora ( Fig. 4C ) with a narrow and rounded exterior lobe (fel). Interior lobe (fil) dentate, roundly triangular and distinctly wider than exterior lobe. Protibiae ( Fig. 4C ) without exterior lobe, interior lobe (til) roundly isosceles triangular (angle> 90°). Exterior and interior lobe of meso- and metafemora gently rounded, with the exterior lobe narrower than the interior lobe. Protarsus about 5/4 the length of the protibia, probasitarsus roughly 2x longer than wide.

Measurements [mm]: Length of body 56.3, length of head 5.0, length of pronotum 3.9, length of mesonotum 4.5, length of tegmina 31.2, greatest width of tegmina 12.3, length of alae 6.7, greatest width of abdomen 23.0, length of profemora 8.4, length of mesofemora 7.8, length of metafemora 9.1, length of protibiae 5.2, length of mesotibiae 5.9, length of metatibiae 6.6, length of antennae 3.4.

Eggs ( Fig. 5 ). Remarkably large when compared to the size of the female. Overall colouration light brown. Lateral surfaces smooth and slightly glossy. Ventral surface with a single longitudinal median lamella (vml) (length 2.9–3.2 mm) consisting of loosely agglutinate hairy or moss-like appendages. Polar area with two very prominent feather-like appendages (pa) (height 1.2–1.8 mm) apparently consisting of thin tightly agglutinate hairy filaments. Dorsal surface generally flat and smooth, with two similar larger and roughly triangular appendages (da; height 1.9–2.2 mm) longitudinally flanking the micropylar plate (mp). Micropylar plate elliptical with pointed ends and slightly impressed ( Fig. 5B ). Micropylar cup (mc) at the posterior end of micropylar plate. Operculum (op) almost circular and slightly convex, with a crown (c) of small hairy appendages ( Fig. 5C ). Medially with a single lamella similar to the one at egg’s the ventral side.

Measurements including feather-like structures and lamellae [mm]: length (including operculum) 5.6–5.9, length 4.8–5.3, width 2.3–2.6, height 4.1–4.3, length of micropylar plate 2.4–2.6.

Distribution and ecology. So far only known from the type locality in the mountain ranges of central West Papua, having been collected in mountainous Nothofagus forest (family Nothofagaceae ) at almost 2000 m above sea level.

Figures

FIGURE 1. Female holotype of Phyllium (Ph.) riedeli n. sp.. A: Dorsal aspect; B: ventral aspect.

FIGURE 2. Head morphology of Phyllium (Ph.) riedeli n. sp.. A: Head capsule, dorsal aspect; B: head capsule, ventral aspect; C: SEM photograph of left antenna; D: antennae, dorsal aspect; E: SEM photograph of antennomere III. III–IX = antennomeres; p = pedicellus; pmt = posteromedian tubercle; pt = protuberance; sc = scapus; sf = stridulatory file; sr = stridulatory ridge.

FIGURE 3. Thorax of Phyllium (Ph.) riedeli n. sp.. A: Pronotum, dorsal aspect; B: prosternum, ventral aspect; C: mesopraescutum and mesopleurae, dorsal aspect; D: mesosternum, ventral aspect; E: rudimentary ala. al = ala; mp = mesopleura; mps = mesopraescutum; t = tegmen.

FIGURE 4. Genitalia and legs of Phyllium (Ph.) riedeli n. sp.. A: Genitalia, ventral aspect; B: meso- and metacoxa, ventral aspect; C: profemur and protibia, dorsal aspect. fel = profemoral exterior lobe; fil = profemoral interior lobe; til = protibial interior lobe; mcx = mesocoxa; mtcx = metacoxa; pf = profemur; ptb = protibia; sp = subgenital plate.

FIGURE 5. Egg of Phyllium (Ph.) riedeli n. sp.. A: Lateral aspect; B: dorsal aspect; C: ventral aspect. c = opercular crown; da = dorsal appendage; mc = micropylar cup; mp = micropylar plate; op = operculum; pa = polar appendage; vml = ventromedian lamella.