Philoscirtus viridulus C. Hemp

Hemp, Claudia, Heller, Klaus-Gerhard, Warchałowska-Śliwa, Elżbieta & Hemp, Andreas, 2015, A new species of Philoscirtus (Orthoptera: Phaneropteridae: Mecopodinae) from the West Usambara Mountains of Tanzania and its conservation status, Zootaxa 3905 (2), pp. 273-282 : 275-279

Philoscirtus viridulus C. Hemp n. sp.

Holotype male: Tanzania, West Usambara Mountains, Lutindi forest, 1250 m, February 2014. Depository: MfN. Paratype. 1 male, same data as holotype (depository collection Hemp); 1 male, Tanzania, West Usambara Mountains, Mazumbai forest reserve (depository BMNH).

Description. Male. General coloration. Predominantly green with some brown to black markings at posterior end of tegmina and dorsally at posterior margins of abdominal segments. Tibiae and knees brown to light brown ( Fig. 1 , 2 ). Posterior margin of subgenital plate shiny black ( Fig. 1 , 3 F). Head and antennae. Antenna very long, 10–11 cm. Face green with pattern of light green to yellowish patches in living insect ( Fig. 2 ). Thorax. Fore femora armed with 1–2 inner stout short spines, marked brown to black at posterior outer side; posterior ends of femora with pointed pair of spurs. Mid femora unarmed, also with a pair of stout and pointed spurs. Hind femora with numerous (5–8) inner and outer stout and acute brown spines and a pair of stout and pointed spurs at lunules. All tibiae with dense spination, especially hind tibiae. Tegmina reaching posterior margin of abdominal segment 2 ( Fig. 3 B, D). The stridulatory file (length 3.0 mm) is found on the underside of the left tegmen. It carries about 110 teeth with intervals of 37 µm in the center ( Fig. 6 ). Abdomen. Cerci green, short and rather stout, slightly inwardly curved with an apical dent and a tiny dent just before the tip on the inner side. Subgenital plate forming a short fork with both apical tips strongly sticking outwards ( Fig. 3 F). With minute styli.

Female. Unknown.

Measurements. male.—(mm) (N = 2): Body length: 29.5–31.8; Median length of pronotum: 5.5–6; length of tegmina: 5.7–5.8; length of hind femur: 29.8–30.2; subgenital plate: 7.7–8.0.

Measurements. (mm) Male Mazumbai (n = 1): Body length: 23.6; Median length of pronotum: 5.1; length of tegmina: 5.0; length of hind femur: 25.3;subgenital plate 7.5.

Diagnosis. P. viridulus n. sp. is less robust than P. cordipennis . The posterior margin of the pronotum is uplifted in P. cordipennis ( Fig. 3 A) but hardly so in P. v i r i du l u s n. sp. ( Fig. 3 B). Compared to P. co rd i p e nn i s the head and pronotum are less rugose in P. viridulus n. sp. Differences are also seen in the subgenital plate. P. cordipennis has an elongated subgenital plate with the median part shaft-like narrowed ( Fig. 3 E) while in P. viridulus n. sp. the middle part is shorter and the tips of the fork are more strongly sticking apart.

Remarks. A single male of P. viridulus n. sp. was found in the collection of the BMNH coming from the Mazumbai forest reserve. It is smaller than the Lutindi specimens and also has a stouter subgenital plate. The tegmina do not reach the posterior margin of the second abdominal segment as in the Lutindi specimens. Molecular and acoustical analyses could clarify the species status.

Song pattern. The song of Philoscirtus viridulus n. sp. was registered only at night. It consisted of short series of echemes (5.1±1.1 echemes; range 3–7; n=30; Fig. 4 ). These echemes contained a variable number of syllables (17.9±1.1 syllables; range 14–20; n=30; counted in the last echeme of a series), repeated in a rhythm of about 20 Hz. The duration of the last syllable varied between 28 and 38 ms (34.6±2.0 ms; n=30). Each syllable contained a quite high number of clearly separated impulse-like sound events.

Spectral composition of song. The frequency spectrum of the song had its maximum at 18.5 kHz (range 10 dB below peak 15–21,4 kHz; Fig. 5).

Chromosomes. The standard karyotype of Philoscirtus viridulus n. sp. consisted of 29 chromosomes in the male, with the X0 sex chromosome system (FN=38; FN is the number of chromosome arms, including the X chromosome). Autosomes can be divided into three size groups: three large submetacentric (L1, L2, L4) and one large acrocentric (L3), six medium acrocentric pairs (M5-7, 9-11) and one medium metacentric (M8) as well as three acrocentric short pairs gradually decreasing in size. The metacentric X chromosome is the largest in the set ( Fig. 7 A). The morphology of the chromosomes is clearly seen in metaphase II ( Fig. 7 B). C-banding of spermatogonial mitotic metaphase and meiotic cells revealed constitutive heterochromatin in the paracentromeric region of most of the chromosomal elements and occupied the region next to the centromere (thick C-bands). Interstitial C-bands were located in one medium pair (M3), additionally telomeric C-bands occurred in most of the large and medium sized autosomes and in both arms of the X chromosome ( Fig. 7 A, C). Silver staining revealed the presence of one large active NOR in the paracentromeric region of the large sized bivalent (L2). It corresponds to a thick heterochromatin block and five “secondary” small NORs (not always visible) on three medium and two small bivalents ( Fig. 7 D). A B chromosome (B), which is supernumerary to the standard complement, being of metacentric type and similar to small sized pairs of autosomes was mitotically and meiotically unstable. From diplotene to metaphase II, this element occurred as univalent or bivalent ( Fig. 7 A, B, C, E).

Biology. P. v i r i du l u s n. sp. individuals were captured at night from small trees and bushes along paths creating some canopy gaps through the closed submontane forest in February 2014. Males and females rested on broad leaves in about 2–3 m height and were very sensitive to disturbance. Therefore only two males could be caught. In October 2014 no individuals could be obtained at the same localities.

Habitat. Submontane and montane forests in the West Usambara Mountains.

Ethyology. From latin: - viridis = green, ending - ulus from latin: small, because it is predominantly green and smaller than P. cordipennnis .

Distribution. West Usambara Mountains, recorded from the Lutindi and Mazumbai forests.

Figures

FIGURE 2. Male P. viridulus n. sp., note pattern of face and legs.

FIGURE 3. Morphological details of male Philoscirtus species. A, C, E. P. cordipennis B, D, F. P. viridulus n. sp.. A, B. Lateral view on abdomen and head C, D. Dorsal view on tegmina, pronotum and head. E, F. Dorsal view on subgenital plate. Scale bars: 4 mm.

FIGURE 4. Oscillograms of the calling song of Philoscirtus viridulus n. sp. A One series of echemes; B One echeme; C Two syllables (from C).

FIGURE 6. Tegmina of Philoscirtus viridulus n. sp., A Left tegmen, lower side, B Left tegmen, upper side, C right tegmen, upper side (in situ; left tegmen removed). Note the rudimentary hind wing. Scale 5 mm.

FIGURE 7. Philoscirtus viridulus n. sp., chromosomes. (A, C, E) C-banding and (B, D) silver nitrate staining of male complement. (A) Karyotypes, arrows indicate interstitial C-bands in autosome pair 3. (B). Metaphase II and (C) diakinesis with marked biarmed chromosomes; B chromosome (the inset in the right corner). (D) Diplotene, large active NOR detected in the paracentromeric region of bivalent 2 and five “ secondary ” small NORs (arrows). (E) Metaphase II and anaphase showing the B chromosome (B). X = sex chromosome; 1, 2, …. number of autosome pairs.

FIGURE 1. P. viridulus n. sp. male habitus.