Merus freidbergi, Friedman, 2019

Friedman, Ariel-Leib-Leonid, 2019, The first record of the genus Merus Gistel (Curculionidae: Molytinae: Mecysolobini) in the Western Palaearctic, with description of Merus freidbergi n. sp. from Israel, Israel Journal of Entomology 49 (2), pp. 351-364 : 355-362

Merus freidbergi n. sp.

( Figs 4–18)

LSID: urn:lsid:zoobank.org:act:2583C863-86E4-4FE2-AD84-6B200AE4753A .

Etymology: This species is dedicated to my dear teacher, supervisor, boss, colleague and friend, Dr Amnon Freidberg, on the occasion of his 75 th anniversary. This is an excellent opportunity to express my deepest appreciation to Amnon as an extraordinary collector, responsible collection curator and top professional entomologist, since the very beginning of his career. Amnon reared these two precious specimens of weevils in 1973, when he was only a PhD student in the Department of Zoology, Tel Aviv University, studying the fruit flies ( Tephritidae ) of Israel. Looking forward and taking care of the science and not just of his own studies, he mounted and labelled carefully these specimens, saving and providing this precious information for future generations. He could not know that one day he would have a student working on weevils; it was three months before this student was born.

Diagnosis: Merus freidbergi n. sp. belongs in the denticulatus species group, being small (3.9–4.1 mm), slender species. Among other members of the species group M. freidbergi possesses a unique pattern of incomplete longitudinal stripes, while covered parts of neighboring interstriae correspond to bare parts and vice versa; tibial ventral tooth is obtuse, rounded, slightly prominent, while in other species it is triangular, pointed, moderately to strongly prominent. Merus freidbergi resembles M. denticulatus , M. cribrithorax , M. albolineatus , M. vicinus and M. kuvanguensis in the body shape, but is much smaller; it has about the same size and shape of the rostrum, head and pronotum as the Southern African M. subtilis and M. exilis , but is wider at the humeri and at the mid-length part of the body. The aedeagus of M. freidbergi is wide, stout, and tapering and pointed at apex, while in other species of the denticulatus -group, of which males were dissected or illustrations were available (e.g. M. albolineatus , M. denticulatus , M. vicinus , M. exilis ), the aedeagus is slenderer, apically truncate, blunt or rounded.

Description: Male ( Figs 4–7, 9, 11, 13–15). Measurements (mm): Body length 3.9, body maximum width 1.7, rostrum length 1.1, pronotum length 1.0, length of elytra 3.2, length of femora and tibia: profemur 1.4, mesofemur 1.2, metafemur 1.1, protibia 1.0, mesotibia 1.0, metatibia 0.8.

Body ( Figs 4–6) oblong oval, with sides in middle part subparallel, integument reddish brown, covered with white and creamy-whitish scales. Dorsal part of body covered with variable types of scales (see description of body parts), ventral part of body covered with appressed fringed scales.

Rostrum ( Figs 4–5, 7, 9) cylindrical, slightly gradually bent, as wide as interocular space, 0.8× as long as pronotum, 0.9× as wide as profemur, at apex slightly widening. Submentum without denticle. Surface of rostrum with partly merged shallow oval punctures and wrinkles. Basal half of rostrum sparsely covered with thin white scales, areas around eye and on gular region with denser stout creamy to yellowish scales. Forehead ( Figs 5, 7, 9) flat, with weak but distinct pit. Eyes ( Figs 5, 7, 9) obovoid, 1.3× as long as wide, flat. Antenna ( Fig. 2) inserted in middle of rostrum. Scape claviform, surface longitudinally wrinkled. Funicular segments glabrous, covered with semi-erect white piliform scales; trapezoidal, successively shortening and widening from 1 st to 6 th segment, 7 th segment as long as 5 th and 6 th segments combined, separated from other segments and incorporated into club. Club oviform, apically acute, densely covered with piliform scales; basal half of 1 st claval segment glabrous. Pronotum ( Figs 4–6, 7, 8) 0.7× as long as wide, in anterior third tapered, with sides rectilinear, in posterior two-thirds expanded, with sides slightly rounded; anterior margin straight, posterior margin sinuate, with wide triangular medial prescutellar lobe. Postocular lobes nearly indistinct. Pronotal disc flat. Surface of pronotum covered with large flat round granules. Pronotum covered with sparse creamy semi-erect scales, inserted between granules, in median part, and with dense white fringed scales, apically fringed to splitted nearly to base into 3–5 rays, in lateral part and along median line; median stripe narrow and more sparsely scaled apically, and wide and densely scaled basally, particularly on prescutellar lobe.

Scutellum ( Fig. 6) distinct, convex, glabrous, not enclosed by basal lobes of elytra, pentagonal, with distinct angular apex.

Elytra ( Figs 4–6) oblong, 1.8× as long as wide at humeri, laterally subparallel, gradually narrowing and rounding in apical third. Basal lobes large, round. Humeri nearly indistinct, rounded. Sculpture of elytra coarse, stria 3× as narrow as interstria, consisting of deep isolated pits; interstriae convex, shiny, transversely wrinkled. Vestiture comprise two types of appressed scales: sparse, minute white and creamy piliform scales, forming irregular rows along interstria, denser on basal half of 1 st interstria; and oval, white scales, fringed apically, forming white stripes: along 3 rd interstria, interrupted medially, on middle one-fourth of 4 th interstria, along bare part of 3 rd interstria, apical half of 7 th interstria and basal half of 9 th interstriae, and form white patches at base of 1 st and 2 nd interstriae, behind middle of 2 nd and 9 th interstriae, and on humeri.

Legs ( Figs 5, 11). Procoxae separated. Femora stout, coarsely punctate, sparsely and regularly covered with fringed scales, swollen in middle part, with large acute ventral tooth. Profemur ( Fig. 11) distally with additional smaller obtuse denticle 0.3× as long as larger tooth. Fore tibia ( Fig. 11) slightly bent, less coarsely punctate than femur, covered with piliform and peg-like white scales, with rounded obtuse ventral tooth, weaker but distinct on meso- and metatibia. All tibiae at apex with long acute mucro and stout premucro. Apical comb distinct, composed of dark peg-like setae. Tarsi densely covered by white piliform scales. 5 th tarsal segment protruding from lobes of 3 rd tarsal segment by more than half of its length. Claws bifid, connate at base.

Abdominal ventrites convex, 5 th ventrite apically rounded, with apical margin fringed with dense setae.

Male terminalia ( Figs 13–15). Aedeagus ( Figs 13, 14) flatten, moderately curved in lateral view, in dorsal view stout, subparallel-sided, at apex strongly tapering and pointed, subapically with a pair of tufts of fine erect setae. Ostial area wide, membranous. Endophallus with fine granulation, visible only at high magnification. Temones as long as tube. Tegminal ring with short pointed ventroapical projection. Spiculum gastrale ( Fig. 15) thin, straight.

Female ( Figs 8, 10, 12, 16–18). Measurements (mm): Body length 4.1, body maximum width 1.8, rostrum length 1.4, pronotum length 1.1, length of elytra 3.3, length of femora and tibia: profemur 1.4, mesofemur 1.2, metafemur 1.2, protibia 1.0, mesotibia 0.9, metatibia 0.9.

Rostrum ( Figs 8, 10) scarcely, longer and narrower than in male. Scutellum distinct, convex, glabrous, spherical, without distinct angular apex. Profemur with additional smaller denticle pointed ( Fig. 9). The single female specimen has colour brighter than the male, probably, because it is teneral.

Female terminalia ( Figs 16–18). Spermatheca ( Fig. 16) C-shaped, sclerotized, duct-lobe (collum, nodulus) apically tapering, gland-lobe (ramus) swollen, produced, tail (cornu) swollen, obtuse. Gonocoxite ( Fig. 17) strongly sclerotized, without styli, with 2 or 3 erect thin setae at apex. Spiculum ventrale ( Fig. 18) weakly sclerotized, with long narrow manubrium and with membranous apical plate.

Holotype: ♂ Israel: W[adi]. Faria , 31.v.1973, A. Freidberg, ex Blepharis attenuata , 20.vi.[19]73 . Paratype: ♀, same data as holotype .

Distribution: Endemic to Israel. The species is so far known from the single locality in the Jordan Valley ( Fig. 23), although its host plant is widely spread throughout all the desert area, particularly along the central and southern areas of the Jordan Valley. It is possible that this species is as common as its host plant, but adults are not found because of their short life-span, nocturnal activity, or being hidden on a lower part of the stem or under the dense and extremely spiny leaves. On the other hand, it is possible that M. freidbergi is extinct or its population has strongly degraded in the last decades as a result of human activity.

Biology: Merus freidbergi was reared from Blepharis attenuata Napper ( Acanthaceae ) ( Figs 19–21). This small, extremely thorny bush is widely distributed throughout the desert areas of Israel, common—but rarely seen in large masses—over the Jordan Valley, the Dead Sea area, in the Samarian and Judean deserts; it is less common in the Negev Desert and the Arava Valley. Three sites with dense populations of B. attenuata have been discovered so far: western slopes of Mt. Sartava in the Samarian Desert ( Fig. 22), spill of Nahal Mezin (Wadi Madin) ( Fig. 21) and spill of Nahal Zeruya in the Dead Sea Area. The original site, where the type specimens were reared from, spill of Nahal Tirza ( Fig. 23), was searched, but no plants were found; they probably disappeared as a result of the intense human activities (road construction, agriculture, etc.). Being an obligatory misanthropic plant, B. attenuata cannot survive close proximity to man ( Danin & Fragman-Sapir 2019). According to Danin and Fragman-Sapir (2019), the vegetative period of B. attenuata lasts from May to December and flowering is in May–December, culminating in September–October. I visited the aforementioned sites several times in different seasons, particularly in May–June, searching for the plant in the suitable condition, but failed to find or to rear additional specimens.

The only known record of the Mecysolobini from the Acanthaceae , Merus unifasciatus Morimoto & Kojima, 2007 from the Rykyu Islands and Taiwan, develops in stems of Strobilanthes tashiroi Hayata ( Acanthaceae ) ( Morimoto & Kojima 2007). However, M. freidbergi is distant from M. unifasciatus both taxonomically and geographically.

Fairly strongly sclerotized gonocoxites suggest that the female is capable of digging into a more or less solid substrate, like stem tissues, for oviposition.