Metapocyrtus silago, Cabras & Senarillos & Ibañez, 2023

Cabras, Analyn A., Senarillos, Tristan Luap P. & Ibañez, Jayson C., 2023, Two New Species of Metapocyrtus Heller, 1912 (Curculionidae: Entiminae: Pachyrhynchini) from Leyte Island, Philippines, Ecologica Montenegrina 67, pp. 66-76 : 70-74

Metapocyrtus silago sp. nov.

https://zoobank.org/ urn:lsid:zoobank.org:act:A4C39C50-1C95-4C04-8B8B-6F167A6190D8

Figs 2 A–D

Holotype ♂ ( Figs 2 A & C ), labeled: “ Philippines – Eastern Visayas / Leyte Island / Province of Southern Leyte / Mt. Nacolod / Municipality of Silago / Barangay Catmon / Sep. 2022 / coll. T. L. P. Senarillos (typed on white card) // Holotype male / Metapocyrtus silago / Cabras, Senarillos, & Ibañez, 2022 (typed on red card)” (Presently in TIRL, will be deposited in PNM) . Paratypes (3 ♂♂, 3 ♀♀): same data of the holotype (all in TIRL) .

Diagnosis. Metapocyrtus silago sp. nov. is related to Metapocyrtus (Trachycyrtus) perarmatus Schultze, 1934 from Panaon Island, Leyte, M. (T.) spinipennis Schultze 1925 from Biliran Island, M. (T.) macrospinosus Schultze 1925 from Camarines Norte, Luzon Island, M. (T.) acutispinosus Schultze 1925 from Samar Island, and M. (T.) crassispinosus Schultze 1925 from Surigao, Mindanao, but can easily be distinguished among its congeners for the reddish-brown integuments of its pronotum and elytra compared to the black integuments of its congeners, and the scaly metallic blue transverse bands at the base and apex of the elytra compared to the random sparse scales of M. (T.) macrospinosus Schultze 1925 , and M. (T.) perarmatus Schultze, 1934 , and the three transverse bands of M. (T.) spinipennis, M. (T.) acutispinosus and and M. (T.) crassispinosus . It differs from M. (T.) spinipennis for the swollen base of apical declivity in females with pubescence which is also present in M. (T.) perarmatus . However, the new species is different from the latter for the following features: smaller size, pronotum with indistinct pubescence appearing almost glabrous, elytra wider than pronotum with tapered apex, and elytra with two transverse scaly bands of metallic blue. Metapocyrtus (T.) perarmatus has smaller and randomly scattered scales on pronotum and elytra. All three species: Metapocyrtus silago sp. nov., M. (T.) perarmatus , and M. (T.) spinipennis are found in Leyte with M. (T.) spinipennis locality in the northern part, M. silago southern and M. (T.) perarmatus southernmost. To easily distinguish the three, M. silago has reddish brown pronotum and elytra with two transverse scaly bands at base and apex; M. (T.) spinipennis is black with scattered scales on pronotum and three transverse bands on elytra whereas M. (T.) perarmatus has black pronotum and elytra with minute pale blue scales scattered randomly ( Fig. 3 ). Similar to the reason mentioned above, we refrain from assigning subgeneric placement.

Description. Male. Dimensions (in mm): LB 6.0– 6.3mm (holotype 6.0mm), LR 1.5–1.8 mm (1.5mm), WR 1.0–1.1 (1.0 mm), LP 2.1–2.5 (2.1mm), WP: 2.5–3.0 (2.5mm), LE 3.8–3.9 (3.8mm), WE 3.0– 3.1 (3.0 mm). N = 2

Coloration. Integuments of head, rostrum, tibia, and tarsi black; prothorax, elytra, antenna, and femora reddish brown. Body surface matte; prothorax, head, rostrum, legs, and underside of elytra weakly lustrous.

Head with sparse and fine pubescence on dorsum, finely punctured; lateral surface below eyes with turquoise elliptical and bluish piliform scales; forehead between eyes slightly raised with distinct median furrow reaching the vertex; eyes small, weakly convex, not prominent on the lateral outline of the head.

Rostrum moderately rugose up to anterior 2/3 rd with sparse white adpressed pubescence, apical third finely punctured with very minute pubescence; lateral sides with white suberect piliform scales; longer than wide (LR/WR: 1.5 mm /1.0 mm); transverse basal groove wide and rugose forming a prominent but shallow medial concavity, base of dorsum slightly elevated forming a very subtle elevated U-shape; rostrum sides with rounded edges; dorsolateral sides near the base with hollow rugose concavity. Antennal scape nearly as long as the funicle, scape reaching just the hind margin of eyes, covered with adpressed white setae, funicle with suberect white setae. Funicular segments I nearly as long as II, segments III-V as long as wide; segments VI-VII slightly wider than long, club sub-ellipsoidal.

Prothorax subglobular, slightly wider than long (LP/WP: 2.0 mm/ 2.2 mm), granulated with very fine pubescence except near the lateral margin which is glabrous, widest at the middle, strongly convex on dorsal surface; with faint stripes of pale blue and turquoise adpressed round scales on anterior and posterior margin, lateral sides sparsely covered with pale blue and turquoise adpressed round scales.

Elytra strongly short ovate (LE/WE: 3.5 mm / 2.5 mm), longer than wide and moderately longer and slightly wider than prothorax (WE/WP: 2.5 mm / 2.2 mm, LE/LP: 3.5 mm /2.0 mm), striate punctate on stria I but becomes irregularly punctured towards dorsolateral sides, dorsum strongly convex, dorsal contour evenly arcuate from base with gradual apical declivity, lateral contour evenly arcuate then gradually tapers with slightly rounded apex, widest at middle, apex with white setae. Each elytron with following scaly markings of metallic blue, turquoise, and golden yellow adpressed round scales: a) a basal band from suture that widens towards the lateral margin, and b) one subtriangular scaly patch on the apical third.

Legs with moderately clavate femora. Femora reddish brown except apex, sparsely covered with minute pubescence, but towards apex covered with suberect and adpressed bluish piliform scales. Fore tibiae covered with subadpressed short brownish setae on outer margin, inner edge with suberect brown setae, and weakly serrated with few denticules. Mid and hind tibiae covered with subadpressed bluish piliform scales on the outer margin and long suberect yellowish setae on inner edge. Fore tibiae and mid tibiae bear a mucro at the apex. Tarsomeres with suberect brown pubescence. Coxae are covered with turquoise piliform scales. Mesothorax with sparse turquoise piliform scales. Metathorax is densely covered with turquoise and blue recumbent round scales. Meso and metaventrite with turquoise piliform scales and sparse turquoise and blue recumbent round scales on distal ends. Ventrite I with setae and blue and turquoise lachrymiform scales on distal ends. Ventrite II-V pubescent.

Male genitalia as shown in Figs 4 D–F .

Female. Dimensions (in mm): LB 6.3–7.0mm, LR 1.3.– 1.5mm, WR 1.0– 1.1mm. LP 2.0– 2.2mm. WP 2.0– 2.9mm, LE 4.1–5.0mm. WE 2.7–3.5mm. N = 3.

Females differ from males in the following: a) rostrum with hump at base but not forming a subtle V-shape and without medial concavity; b) pronotum with sparse blue round scales, c) elytra longer and wider, d) elytra has coarser punctures compared to male, with a small protuberance of white tuft of hairs at the onset of apical declivity, elytra with two pointed conical projections with white suberect piliform scales; and e) Ventrite I more bulging on disc. Otherwise, females are similar to the male.

Etymology. The specific epithet is a toponym referring to the type locality Municipality of Silago, Southern Leyte, Philippines.

Distribution. Metapocyrtus silago sp. nov. is known so far from Mt. Nacolod, Southern Leyte, Philippines.

Brief Ecological Note

Metapocyrtus nacolod sp. nov. was collected in Mt. Nacolod, Barangay Catmon, Municipality of Silago, Southern Leyte at 720 – 726 meters above sea level (masl). The collection site is an old logging road, and the area is characterized as a transition between the upper dipterocarp and montane forests ( Fig. 5 A – B ). Based on preliminary observations, Metapocyrtus nacolod sp. nov. individuals prefer cool and shaded areas. All M. nacolod specimens were found and collected only within the understory vegetation ( Fig. 5 E – F ). Dominant plants were primarily of the genera Alpinia and Calamus , with various species of tree ferns, ground ferns, tree wildings, and other weeds. The collection site was appropriately 75 m away from the nearest stream. No individuals were found in areas below 700 masl.

Metapocyrtus silago sp. nov. was found only within the understory vegetation of the interior forest surrounding Barangay Catmon ( Fig. 5 C – D ). The collection site is a lowland dipterocarp forest around 232— 361 masl, dominated by towering premium tree species such as Red Lauan ( Shorea negrosensis Foxw. ). This species appears restricted only at the lower slopes of Mt. Nacolod, compared to M. nacolod sp. nov. which is found at the middle to high-elevation forests of the same mountain.

Conservation Implications

The discovery of these two previously undescribed species underscores the need for more natural history studies in the Philippine archipelago. In this critical era of biodiversity crisis, basic taxonomic expeditions can help prevent silent species extinctions. Once “new species” are given their proper scientific names, this becomes a springboard for studying their habits and defining their geographical distribution thereby augmenting our understanding of species history and potentially influencing their future conservation efforts. As one of the world’s megadiverse countries, many more unique organisms await discovery in the Philippines.

The discovery of M. nacolod sp. nov. and M. silago sp. nov. serves as compelling evidence of the critical ecological significance of the Mt. Nacolod Mountain range. These two new species, combined with pre-existing data on unique flora and fauna from Mt. Nacolod, highlight its remarkable ecological and evolutionary role as a center of species endemism. Consequently, it deserves a national Protected Area (PA) designation. As the last remaining large block of forest in Southern Leyte, the area’s management as a PA spares this precious KBA, and all its biological inhabitants from anthropogenic threats and destruction.

Figures

Figure 2 A–D. Metapocyrtus silago sp. nov. A male holotype, dorsal view B female, dorsal view C ditto, male, lateral view D ditto, female, lateral view.

Figure 3 A–B. Metapocyrtus (T.) spinipennis. A male type, dorsal view B idem, lateral view. C–D. Metapocyrtus (T.) perarmatus C male type, dorsal view D idem, lateral view. Photo by Olaf Jager (SMTD)

Figures 4 A–F. Male genitalia of Metapocyrtus species: A–C Metapocyrtus nacolod sp. nov. D–F Metapocyrtus silago sp. nov.; A, D aedeagus in lateral view B, E idem. in dorsal view C, F sternite IX in dorsal view.

Figure 5. Habitat of Metapocyrtus spp. A–B. Collection site of Metapocyrtus nacolod sp. nov. in Mt. Nacolod at an upper dipterocarp- montane forest (700-800). C–D. Collection site of Metapocyrtus silago sp. nov. Mt. Nacolod at a lowland dipterocarp forest (200-300 masl). E–F Metapocyrtus nacolod sp. nov in its natural habitat.