Short Communication

Abstract: Genus Atmetonychus Schoenherr (1840) known from India and Bangladesh is revised. The generic and species description has been updated through addition of measurements, description of elytral vestiture and genitalic characters. These are supported by 28 illustrations including 21 line diagrams.

Keywords: Entiminae, redescription, taxonomy, weevils.

Marshall (1916) included the genus Atmetonychus under the group Tanymecides of the subfamily Brachyderinae under the division Adelognathi. Emden (1944) categorized it under the subtribe Piazomiina of tribe Tanymecini of Brachyderinae. But, Thompson (1992) brought under Entiminae, and Alonso-Zarazaga & Lyal (1999) included it under the subtribe Piazomiina, of the tribe Tanymecini. The tribe Tanymecini is recognized by the presence of vibrissae on the prothorax, while the subtribe Piazomiina is characterized by its connate claws or their fusion into a single claw. Presently, Atmetonychus is under the subtribe Piazomiina of the tribe Tanymecini under the subfamily Entiminae of Curculionidae. Atmetonychus was first described by Schoenherr (1840). Later, Marshall (1916) redescribed and provided a key. Pajni & Gandhi (1984) added male and female genitalia to its description.

Only one species described till date, namely, peregrinus, which was described under Curculio by Olivier (1807) and later designated as the type species by Schoenherr (1840). Marshall (1916) synonymized inaequalis (Boheman) with peregrinus (Olivier). Pajni & Gandhi (1984) described the genitalia structure of perigrinus. It was also observed that the tibial apex in this species is enclosed as pointed out by van Emden (1944) and not open as stated by Marshall (1916). Atmetonychus is known so far from India and Bangladesh, in India it is known from Assam, Bihar, Haryana, Himachal Pradesh, Odisha, Uttar Pradesh and West Bengal.

As per economic importance, Atmetonychus perigrinus had been reported as a pest of Mangifera indica, Prunus persica and Prunus communis (Stebbing, 1914); Zizyphus mauritiana (Beeson, 1941; Browne, 1968); Terminalia arjuna and T. tomentosa (Mishra et al. 1995).

Material and Methods

Voucher material including types deposited at National Pusa Collection (NPC), Division of Entomology, Indian Agricultural Research Institute, New Delhi. The methodology and terminology was followed (Supare et al. 1990; Thompson 1992; Poorani & Ramamurthy 1997; Wanat 2007). WILD M8 stereozoom microscope, Leica MZ 16A stereozoom microscope, LEITZ ORTHOLUX II interference, phase contrast, compound microscope, and Leica DFC-290 camera attached with Leica application suit ver. 2.8.2 were used in the taxonomic studies. Illustrations were made using a drawing tube fitted with a camera lucida. The scales of magnification are provided on the illustrations.

Results

Taxonomic studies

Genus Atmetonychus Schoenherr, 1840: 214.

Agrestus Wiedemann, 1823:164; Alonso Zarazaga and Lyal, 1999:180.

Gender: Masculine

Type species Curculio peregrinus Olivier, 1807: 324

Genus description

General colour black with uniform grey or brownish vestiture and ventrally paler. Head with frons projecting laterally above eyes, which are lateral, very prominent. Rostrum continuous with and 1.54x as long as head, plane above, angulate laterally, triangularly emarginate at apex, scrobes deep, gently curved, passing below eyes and becoming wider and shallower, mandibles not prominent, with a distinct scar, mentum large, quite filling cavity, submentum without peduncle (Fig. 1). Antennae with scape gradually clavate and reaching eye (Fig. 2), first funicle segment 1.48x longer than second, third to seventh subequal, 1.16x broader than long and closely set, club four segmented and sharply acuminate (Fig. 4). Prothorax bisinuate at posterior margin, vertically truncate at anterior margin, anterior margin not sinuate ventrally. Scutellum 1.48x longer than broad. Elytra subtruncate at basal margin, 1.45x broader than prothorax at shoulders, which are roundly rectangular and gradually narrowing from there to apex, with ten shallow sulci, margins broadly sinuate above hind coxae, posterior declivity sloping gradually. Elytral vestiture of two types, predominant flat, subcircular to ovate, with irregular impressions on surface, brown, with hyaline outer core (Figs. 10, 11), less predominant very elongate, with a subrectangular pedicel, more granulations at basal half and dull white (Figs. 12, 13). Sternum with fore coxae at middle of prosternum, mesosternum with epimera large, almost as long as episterna, metasternum 1.37x longer than middle coxae, episterna distinct and fairly broad, hind coxae not reaching the elytra. Venter with intercoxal process rounded and 0.72x narrower than hind coxae, second ventrite 1.55x longer than third and fourth together and separated from first by a curved incision, (Fig. 6). Legs with hind femora not clavate, middle and fore femora moderately so, tibiae almost straight, fore tibia produced internally at apex, hind tibial apex enclosed, tarsi with second segment triangular and 1.32x longer than broad, third segment 1.10x broader than second, fourth elongate and with a single, long claw (Fig. 7). Male genitalia with aedeagus 2.44x as long as apophyses, 1.56x as its median lobe, 1.22x as long as spiculum gastrale, 1.78x as long as the tegmen, median lobe sclerotized, apex triangular, bow shaped laterally, with sharply pointed apex, 2.09x as long as manubrium. Apophyses 0.64x as broad as manubrium (Figs. 17, 18, 19, 25). Tegmen 1.9x as long as manubrium, parameres elongate, apex bluntly rounded, manubrium slightly broader at base (Fig. 21). Spiculum gastrale 2x as long as apophyses and 1.46x as long as tegmen, uniformly thick with bluntly pointed apex, 3x as broad as apophyses and 1.88x as broad as that of manubrium (Fig. 20; Image 5). Female genitalia having spermatheca with distal arm 1.39x as long as proximal; nodulus distinct and rounded; ramus projecting out, subrectangular, apex moderately rounded; cornu straight, tubular, apex rounded, slightly projecting away from proximal arm (Figs. 14, 15, 22; Image 2). Spiculum ventrale with shaft elongate, 1.46x as long as basal plate, apex constricted and clubbed, basal plate 1.28x as broad as long, apex rounded with hairs (Fig. 16; Image 3).

Species description

Atmetonychus peregrinus (Olivier)

(Figs. 1–21; Images 1–7)

Synonyms

Curculio peregrinus Olivier, 1807: 324; Schoenherr, 1840: 214.

Anaemerus peregrinus Gyllenhal in Schoenherr, 1834: 75; Marshall, 1916: 112.

Curculio rugosus Wiedemann in Germar, 1821: 155; Sturm, 1843: 193.

inaequalis Boheman in Schoenherr, 1840: 214; Marshall, 1916: 112.

Specimens examined: Location, date and coll. unknown, 4 specimens; Bangladesh and Assam, 1.viii.1907, coll. B. Singh; Assam: Tejpur, 12.iv.1977, coll. unknown, at tube light, 4 specimens; Barah, Silchar, 18.iv.1986, coll. Dalip. K, on soil; Lakhimpur, 28.iv.1980, coll. unknown, on wild plant; Bihar: Pusa, 1907, Coll. D.P.S.; 1907, coll. H.M.L.; vii.1906, coll. D.P.S., on ber; Chapra, date unknown, Mackenzie coll., 7 specimens; Chapra, date and coll. unknown; Haryana: Ambala, 6.viii.1906, coll. U.N.S., on bhendi; Himachal Pradesh: Bilaspur, 9.ix.1977, coll. unknown, on berry, 3 specimens; Kangra forest, 18.vii.1985, coll. B. Singh, on bushes, 5 specimens; Kangra, 19.vii.1985, coll. B. Singh, on berry, 2 specimens; Orissa: Cuttack, 28.xii.1906, coll. D.N.P., on potato leaves; Punjab: Gurdaspur, 26.x.1918, A.G.R. coll.; Uttar Pradesh: Faizabad, Uttar Pradesh, 16.xii.1904, coll. unknown, on Papaver somniferum.

Description: General colour black with uniform grey or brownish vestiture, under parts paler (Images 6,7). Head 1.94x broader than long, constricted behind eye, frons with a deep central furrow and a broad shallow one on each side, 0.67x as long as rostrum, 0.48x as long as that of prothorax, 1.19x as broad as rostrum and 0.66x as broad as the prothorax. Rostrum almost parallel sided in male, 0.89x narrowed from the base to the middle in female, as long as broad, 0.85x as long as base of head, plane above, with a deep central furrow and a broad curved one on each side (Figs. 1, 2). Antennae with first segment longest, 1.53x, 2.06x, 1.95x, 1.80x and 1.60x as long as second, third and fourth, fifth, sixth and seventh, respectively; in terms of breadth, seventh segment broadest of all, 1.14x, 1.25x and 1.20x as broad as first and sixth, second to fourth, and fifth, respectively and segments second to fourth equally broad. Club 2.06x as long as first, and 3.28x as long and 1.36x as broad as seventh segment of funicle (Fig. 4). Prothorax 1.4x as long as and 1.8x as broad as rostrum, broadest at base, 1.3x broader than long at base; breadth at base 1.26x as broad as at apex, posterior angles acute, sides almost straight and anterior angles shortly but acutely projecting, upper surface very rugose and uneven, with a deep central depression (Fig. 3). Legs black, with grey vestiture, upper edges with dense short setae, ventral surface with much longer setae, and femora rugosely punctate, tibiae almost straight, tibial apex enclosed (Fig. 8, 9), claw single, long (Fig. 7). Elytra 4.67x as long as rostrum, 3.35x as long as 1.53x as broad as that of prothorax, 1.38x broad as that of its breadth at base, gradually acuminate behind, apices separately mucronate, with shallow sucli, containing large deep punctations, intervals narrow and very uneven with short, subdepressed vesiture, which are often denser and longer in small irregular patches (Fig. 5; Image 6,7). Elytral vestiture of two types, predominant flat, subcircular to ovate, with irregular impression on the surface and brown with hyaline outer core (Fig. 10, 11); less predominant very elongate, with a subrectangular pedicel, more granulations at basal half and dull white (Fig. 12, 13). Venter with first ventrite longest, 1.30x, 4.12x and 1.73x as long as second, third and fourth and fifth, respectively; in term of breadth, first the broadest,1.12x, 1.44x, 1.66x and 2.01x as broad as second, third, fourth and fifth, respectively (Fig. 6). Male genitalia with aedeagus 2.44x as long as apophyses, 1.56x as its median lobe, 1.22x as long as spiculum gastrale, 1.78x as long as the tegmen; median lobe sclerotized, apex triangular, bow shaped laterally with sharply pointed apex, 2.09x as long as manubrium; its base 1.39x as broad as middle and 1.2x as broad as breadth just before apex and 1.16x broad as at middle, from sides 11x as broad as that of apophyses. Apophyses 0.64x as broad as manubrium (Figs. 17, 18, 19; Image 4). Tegmen 1.9x as long as manubrium, parameres elongate, apex bluntly rounded, manubrium slightly broader at base (Fig. 21). Spiculum gastrale 2x as long as apophyses and 1.46x as long as tegmen, uniformly thick with bluntly pointed apex, its breadth 3x as broad as apophyses and 1.88x as broad as that of manubrium (Fig. 20; Image 5). Female genitalia having spermatheca with distal arm 1.39x as long as proximal, nodulus distinct and rounded, ramus projecting out, subrectangular, apex moderately rounded, cornu stright, tubular, apex rounded, slightly projecting away from proximal arm (Figs. 14, 15; Images 1, 2). Spiculum ventrale with shaft elongate, 1.46x as long as basal plate, slightly broader at middle, apex constricted and clubbed, basal plate 1.28x as broad as long, apex rounded with hairs (Fig. 16; Image 3).

Length: 13.49±0.71 mm; Breadth: 4.81±0.31 mm.

Host: Mango (Mangifera indica), Prunus persica, P. communis, Zizyphus mauritiana, Ber, Bhendi, Berry, Potato, Papaver somniferum, Terminalia arjuna and T. tomentosa.

Distribution: India (Assam: Tejpur, Silchar, Lakhimpur; Bihar: Pusa, Chapra; Haryana: Ambala; Himachal Pradesh: Kangra, Bilaspur; Odisha: Cuttack; Punjab: Gurdaspur; Uttar Pradesh: Faizabad; West Bengal: Kolkata). Bangladesh (exact location unknown).

Remarks: The tibial apex in the present species is enclosed (van Emden 1944), and not open as stated by Marshall (1916).

Discussion

This genus first described by Schoenherr (1840b), was included by Marshall (1916) under Tanymecides of Brachyderinae under the division Adelognathi, while van Emden (1944) categorized it under Piazomiina of Tanymecini. Thompson (1992) concluded that is an Entiminae. The concept of the genus developing now indicates that the tarsi having only a single claw is an important character for the distinction of the genus. Van Emden (1944) distinguished this genus by the character of single one claw, third tarsal segment distinctly broader and deeply bilobed, and tibial apex enclosed. Pajni & Gandhi (1984) differentiated it from Hypomeces, by the same characters. Results of the present study corroborate the views of van Emden (1944) and Pajni & Gandhi (1984). The available taxonomic information including that of Pajni & Gandhi (1984) are obsolete and require augmentation. Additions of structure of male and female genitalia, especially clarity in the diagrams on medial lobe, tegmen and spiculum gastrale have been achieved now.

References

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