Journal of Threatened Taxa | www.threatenedtaxa.org | 26 January 2024 | 16(1): 24601–24606

 

ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print) 

https://doi.org/10.11609/jott.8629.16.1.24601-24606

#8629 | Received 11 July 2023 | Final received 20 November 2023 | Finally accepted 20 December 2023

 

 

Two new weevil species of the genus Myllocerus Schoenherr, 1823 (Coleoptera: Curculionidae: Entiminae) from India

 

G. Mahendiran 1, M.M. Nagaraja 2 & M. Sampathkumar 3

 

1,2,3 Division of Germplasm Collection and Characterisation, ICAR-National Bureau of Agricultural Insect Resources, Bengaluru,

Karnataka 560024, India.

1 mahi.weevils@gmail.com (corresponding author), 2 nagumm1995@gmail.com, 3 ento_sam@yahoo.co.in

 

 

ZooBank: urn:lsid:zoobank.org:pub:7DC75BF3-005B-4CCC-98AF-F54F37EB8BCA

 

Editor: Andrei A. Legalov, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia.               Date of publication: 26 January 2024 (online & print)

 

Citation: Mahendiran, G., M.M. Nagaraja & M. Sampathkumar (2024). Two new weevil species of the genus Myllocerus Schoenherr, 1823 (Coleoptera: Curculionidae: Entiminae) from India. Journal of Threatened Taxa 16(1): 24601–24606. https://doi.org/10.11609/jott.8629.16.1.24601-24606

  

Copyright: © Mahendiran et al. 2024. Creative Commons Attribution 4.0 International License.  JoTT allows unrestricted use, reproduction, and distribution of this article in any medium by providing adequate credit to the author(s) and the source of publication.

 

Funding: This study is financially supported by the Science and Engineering Research Board (SERB), Department of Science and Technology, Government of India under Core Research Grant (CRG/2021/007862) with the project entitled “Biodiversity and Systematics studies on Weevils (Curculionidae: Coleoptera) with a special reference to Eastern Ghats of India”.

 

Competing interests: The authors declare no competing interests.

 

Acknowledgements: The authors are highly thankful to the Director, ICAR-NBAIR, Bengaluru for providing the necessary facilities and to the Science and Engineering Research Board (SERB), Department of Science and Technology, Government of India (CRG/2021/007862) for financial assistance.

 

 

Abstract: Two new species, Myllocerus vathalmalaensis sp. nov. and M. depressus sp. nov., are described from India. M. vathalmalaensis differs from M. lineaticollis (Boheman, 1842) in possessing a fine central carina on the impressed rostrum, the second funicle segment longer than the first one and tegmen without parameres. M. depressus differs from M. cardoni Marshall, 1916 by the dorsally depressed rostrum, which is longer than the head, a prothorax depressed and constricted near the posterior margin, the antennae and legs black in colour, the hind femora with a single spine and a spermatheca with curved nodulus.

 

Keywords: Broad nose weevil, Curculionoidea, Cyphicerini, oriental region, rostrum, snout beetles, weevil.

 

 

The Curculionidae (weevils) is one of the largest animal families comprising of 5,800 genera and 62,000 described species (Oberprieler 2007) in 16 subfamilies globally, and are widely distributed. Some of them are serious pest of many crops, including agricultural, horticultural, and forest crops. They feed on leaves, flowers, fruits, seeds, stems, roots and are also recorded in storage houses. They are documented as potential weed control agents, pollinators of crops, and playing an important role in maintaining the natural ecosystem. The genus Myllocerus Schoenherr, 1823 is one of the economically important genera, causing severe defoliation during the adult stage, while the grubs feed on the rootlets of many plants (O’Brien et al. 2006).

The genus Myllocerus was first described by Schoenherr (1823), with the type species Curculio curvicornis Fabricius. Three-hundred-and-fifty-four species have been described in this genus worldwide, of which 86 species have been recorded from India (Ramamurthy & Ghai 1988; Ramamurthy et al. 1992). This genus can be distinguished from other closely related genera by the following characters: the rostrum continuous with the head, its apex emarginated symmetrically, the epistome bounded by distinct carinae, the scrobes subdorsal or dorsal and broad, antennae with scape extending beyond the front margin of the thorax, the procoxae almost in the middle of the prosternum and claws free (Ramamurthy & Ghai 1988). Currently, it is placed under the subtribe Myllocerina, tribe Cyphicerini, and subfamily Entiminae (Alonso-Zarazaga & Lyal 1999).

Marshall (1916) was the pioneering researcher who studied 71 species including 42 new species and provided a key to identifying the species from British India. Ramamurthy & Ghai (1988) redescribed the genus Myllocerus, examining 73 species, including 15 new species from India and adjacent countries. Ramamurthy et al. (1992) transferred six species to the genus Myllocerus and synonymised the name Hyperstylus Roelofs, 1873 with Myllocerus, and additionally described three new species under Myllocerus. Following Ramamurthy et al. (1992), there has been a scarcity of taxonomic studies on Myllocerus in India.

This paper focuses on describing of two new species of Myllocerus from Tamil Nadu, Karnataka, Telangana, and Andhra Pradesh.

 

Material and Methods

The studied specimens were collected during the survey conducted in different regions of India from 2016 to 2021. The morphological characters were studied using standard techniques for dried insect specimens (Marshall 1916; Ramamurthy & Ghai 1988). The diagnostic characters were photographed using Lecia M205A stereozoom microscope with AutoMontage facility utilizing Leica application suite V4.12 software.

The identification keys provided by Marshall (1916) and Ramamurthy & Ghai (1988) were used for identifying the species. Original descriptions and authentically identified specimens were compared. Standard terminologies were used for the species description following glossary of weevil characters by C.H.C. Lyal (2021) in International Weevil Community website. The type specimens are deposited in the National Insect Museum, ICAR-National Bureau of Agricultural Insect Resources (ICAR-NBAIR), Bengaluru.

 

Results

 

1. Myllocerus vathalmalaiensis Mahendiran, sp. nov.
(Image 1A–K)
urn:lsid:zoobank.org:act:F6E1EEA4-06E0-42B0-9A4D-24DCE482B305

 

Material examined: Holotype: Male, NIM/NBAIR/COL/MYLL/H-201223-A, 25.viii.2014,  India: Tamil Nadu: Vathalmalai, Palsilambu, 12°02’50’’N 78°13’51’’E, 1,047 m, coll. G. Mahendiran, on C. leaves,  National Insect Museum (NIM), ICAR-NBAIR, Bengaluru, India.

Paratypes: 10 specimens, NIM/NBAIR/COL/MYLL/P1-201223-A, NIM/NBAIR/COL/MYLL/P2-201223-A, NIM/NBAIR/COL/MYLL/P3-201223-A, NIM/NBAIR/COL/MYLL/P4-201223-A, NIM/NBAIR/COL/MYLL/P5-201223-A, NIM/NBAIR/COL/MYLL/P6-201223-A NIM/NBAIR/COL/MYLL/P7-201223-A, NIM/NBAIR/COL/MYLL/P8-201223-A, NIM/NBAIR/COL/MYLL/P9-201223-A, NIM/NBAIR/COL/MYLL/P10-201223-A, same data as holotype (NIM).

Diagnostic characters: This species can be distinguished from M. lineoaticollis (Boheman, 1842) in possessing a fine central carina on the impressed rostrum, the second funicle segment longer than the first one and a tegmen without parameres.

Description: Body length (without rostrum) 5.09–6.64 mm; width 1.80–2.51 mm; rostrum length 0.76–0.93 mm, width 0.91–1.08 mm. Body: colour black, covered uniformly with dense greenish scales laterally, brownish scales on dorsal side. Head: with prominent eyes, which is convex, oval and dorso-lateral in position, forehead broader than the space between the scrobes (Image 1A & B). Rostrum: as long as head, with apical emergination well defined forming an acute angle, impressed dorsally, with a fine central carina, which reaches middle of the head, sides narrowed gradually then dilated at apex. Antennae: reddish-brown or black, covered with fine whitish setae, scape slightly bent in middle, funicle segment second longer than first, other segments subequal (Image 1F). Pronotum: slightly broader than long, weakly rounded at sides, anterior margin slightly broader than posterior margin, broadest about middle and shallowly constricted before and behind the middle, depressed posteriorly, covered with rounded greenish scales with strips of brownish narrow scales on dorsal side (Image 1C). Legs: black or reddish brown, covered with green scales and white setaes, all femora with a single sharp spine at middle. Elytra: with distinct humeri, base subtruncate and slightly sinuate in middle, broadest behind the middle, punctato-striate, rounded green scale densely covered lateral parts, dorsally marked with irregular patches of brown scales, also covered with long, stout, erect setae (Image 1D & E). Male genitalia: aedeagus with penis membranous, apophyses longer than penis and moderately chitinised; tegmen without parameres, manubarium longer and slender; spiculum gastrale stouter, with strongly curved flattened apex (Image 1G–I). Female genitalia: spermatheca with nodulus stout, rounded; ramus distinct, perpendicular to proximal arm; cornu narrowing toward apex, apex curved and bluntly pointed (Image 1J). Spiculum ventrale with shaft elongate, thicker in the middle and narrowing towards both ends basal plate bilobed, its apex clubbed (Image 1K).

Etymology: The species name is the latinised form of its type locality, Vathalmalai.

Host plant: Curry Leaf Murraya koenigii (L.) Spreng.

Distribution: India: Tamil Nadu.

 

2. Myllocerus depressus Mahendiran, sp. nov.
(Image 2A–K)
urn:lsid:zoobank.org:act:561E201C-53B8-4860-B82F-5026B7683E6A

 

Material examined: Holotype: Male, NIM/NBAIR/COL/MYLL/H-201223-B, 6.ix.2018, India: Andhra Pradesh: Rajahmundry: Dowalaiwarum, 16°57’53.8”N 81°47’08.0”E, on Pongamia pinnata L., coll. G. Mahendiran, National Insect Museum (NIM), ICAR-NBAIR, Bengaluru, India.

Paratypes: 4 specimens, NIM/NBAIR/COL/MYLL/P1-201223-B, NIM/NBAIR/COL/MYLL/P2-201223-B, NIM/NBAIR/COL/MYLL/P3-201223-B, NIM/NBAIR/COL/MYLL/P4-201223-B, same as holotype, on Water Apple Syzygium aqueum Burm.; 2 specimens, NIM/NBAIR/COL/MYLL/P5-201223-B, NIM/NBAIR/COL/MYLL/P6-201223-B, same as holotype, on Cacao Theobrama cacao L.; 2 specimens, NIM/NBAIR/COL/MYLL/P7-201223-B, NIM/NBAIR/COL/MYLL/P8-201223-B, 13.x.2018, Telangana, Hyderabad, Rajendranagar, 17°19’23.2”N 78°23’57.3”E, on Water Apple, coll. M.M. Nagaraja; 2 specimens, NIM/NBAIR/COL/MYLL/P9-201223-B, NIM/NBAIR/COL/MYLL/P10-201223-B, 13.x.2018, Telangana, Hyderabad, Rajendranagar, 17°19’23.2”N 78°23’57.3”E, on Acacia sp., coll. M.M. Nagaraja; 2 specimens, NIM/NBAIR/COL/MYLL/P11-201223-B, NIM/NBAIR/COL/MYLL/P12-201223-B, 15.x.2018, Telangana, Hyderabad, Rajendranagar, 17°19’23.2”N 78°23’57.3”E, on Jamoon Syzygium cumini L., coll. M.M. Nagaraja; 1 specimen, NIM/NBAIR/COL/MYLL/P13-201223-B, 15.x.2018, Telangana, Hyderabad, Rajendranagar, 17°19’23.2”N 78°23’57.3”E, Mango Mangifera indica L., coll. M.M. Nagaraja; 1 specimen, NIM/NBAIR/COL/MYLL/P14-201223-B, Telangana, Hyderabad, Rajendranagar, 17°19’23.2”N 78°23’57.3”E, 21.x.2018, Sapota, coll. M.M. Nagaraja; 2 specimens, NIM/NBAIR/COL/MYLL/P15-201223-B, NIM/NBAIR/COL/MYLL/P16-201223-B, Telangana, Hyderabad, Rajendranagar, 17°19’23.2”N 78°23’57.3”E, 14.x.2018, Raintree Samanea saman Jacq., coll. M.M. Nagaraja; 1 specimen,  NIM/NBAIR/COL/MYLL/P17-201223-B, Telangana, Hyderabad, Rajendranagar, 17°19’23.2”N 78°23’57.3”E, 14.x.2018, Tulip Tree Liriodendron tulipifera L., coll. M.M. Nagaraja; 2 specimens, NIM/NBAIR/COL/ MYLL/ P18-201223-B, NIM/NBAIR/COL/MYLL/P19-201223-B, Telangana, Hyderabad, Rajendranagar, 17°19’23.2”N 78°23’57.3”E, 14.x.2018, Pongamia pinnata, coll. M.M. Nagaraja; 2 specimens, NIM/NBAIR/COL/MYLL/P20-201223-B, NIM/NBAIR/COL/MYLL/P21-201223-B, Telangana, Hyderabad, Rajendranagar, 17°19’23.2”N 78°23’57.3”E, 14.x.2018, ornamental plant, coll. M.M. Nagaraja; 2 specimens, NIM/NBAIR/COL/MYLL/P22-201223-B, NIM/NBAIR/COL/MYLL/P23-201223-B, Telangana, Hyderabad, Rajendranagar, 17°19’23.2”N 78°23’57.3”E, 15.x.2018, ornamental plant, coll. M.M. Nagaraja; 1 specimen, NIM/NBAIR/COL/MYLL/P24-201223-B, Telangana, Hyderabad, Rajendranagar, 17°19’23.2”N 78°23’57.3”E, 15.x.2018, Lemon, coll. M.M. Nagaraja; 3 specimens, NIM/NBAIR/COL/MYLL/P25-201223-B, NIM/NBAIR/COL/MYLL/P26-201223-B, NIM/NBAIR/COL/MYLL/P27-201223-B, Tamil Nadu, TNAU, Coimbatore, 11°14’00.0”N 77°18’00.0”E, 21.ix.2018, Sapota Manilkara zapota Mill., coll. M.M. Nagaraja; 1 specimen, NIM/NBAIR/COL/MYLL/P28-201223-B, Tamil Nadu, TNAU, Coimbatore, 11°14’00.0”N 77°18’00.0”E, 21.ix.2018, Jamoon Syzygium cumini L., coll. M.M. Nagaraja; 2 specimens, NIM/NBAIR/COL/MYLL/P29-201223-B, NIM/NBAIR/COL/MYLL/P30-201223-B, Tamil Nadu, TNAU, Coimbatore, 11°14’00.0”N 77°18’00.0”E, 22.ix.2018, ornamental plant, coll. M.M. Nagaraja; 1 specimen, NIM/NBAIR/COL/MYLL/P31-201223-B, Tamil Nadu, TNAU, Coimbatore, 11°14’00.0”N 77°18’00.0”E, 22.ix.2018, Lucern, coll. M.M. Nagaraja; 1 specimen, NIM/NBAIR/COL/MYLL/P32-201223-B, Tamil Nadu, TNAU, Coimbatore, 11°14’00.0”N 77°18’00.0”E, 20.ix.2018, Sunflower Helianthus annuus L., coll. M.M. Nagaraja. The types are deposited in the National Insect Museum (NIM), ICAR-NBAIR, Bengaluru, India.

Diagnostic characters: This species can be distinguished from M. cardoni Marshall, 1916 by having the dorsally depressed rostrum, which is longer than the head, a prothorax depressed and constricted near the posterior margin, the antennae and legs black in colour, the hind femora with a single spine and a spermatheca with curved nodulus. 

Description: Body length (without rostrum) 6.50–8.60 mm; width 2.52–3.79 mm; rostrum length 0.94–1.31 mm, width 1.21–1.58 mm. Body: colour black, covered with dense dull whitish, which prominent laterally, elytra variegated with irregular patches of brown scales. Head: with eyes subdorsal, forehead little broader than space between the scrobes. Rostrum: longer than head, broader than long, sides subparallel, dilated at apex, the apical emergination deep and acute in angle, distinctly depressed dorsally, with a fine central carinae, lateral carina subparallel, sides narrowed gradually then dilated at apex (Image 2A & B). Antennae: black, covered with fine whitish setae, scape stout, gradually widening base to apex, curved at base, funicle segment second longer than first, other segments subequal (Image 2F). Pronotum: much broader than long, sides slightly rounded before middle, broadest about middle, constricted and depressed near posterior margin, anterior margin truncate, posterior margin slightly bisinuate, shallowly punctate dorsally (Image 2C). Legs: black, covered with whitish scales and setaes, all femors with a single sharp spine. Elytra: with distinct shoulders, base separately rounded, broadest behind the middle, punctato-striate, scales depressed, less prominent, dorsally marked with irregular patches of brown scales, without erect setae (Image 2D & E). Male genitalia: aedeagus with penis broader with distinct apical processes, apex sinuate and chtinised; apophyses longer than penis; tegmen without parameres, manubarium longer and slender; spiculum gastrale stout, much thicker than apophyses, apex flattened, strongly covered (Image 2G–I). Female genitalia: spermatheca with nodulus prominent, curved backward; ramus distinct, rounded, cornu slightly curved, apex bluntly pointed (Image 2J). Spiculum ventrale with shaft very long, thicker, basal plate broadly rounded, its apex slightly flattened (Image 2K).

Etymology: The species name ‘depressus’ derived from the verb ‘depress’ (press down) + “-us” (adjective- derivational suffix) denoting its depressed rostrum dorsally.

Distribution: India: Tamil Nadu, Karnataka, Telangana and Andhra Pradesh

Host plant: Pongamia pinnata L., Water Apple Syzygium aqueum Burm., Cacao Theobroma cacao L., Acacia sp., Jamoon Syzygium cumini L., Mango Mangifera indica L., Sapota Manilkara zapota Mill., Raintree Samanea saman Jacq., Tulip Tree Liriodendron tulipifera L., Lemon Citrus limon L., Lucerne Medicago sativa L., Sunflower Helianthus annuus L. and ornamental plants.

Discussion

Myllocerus vathalmalaensis sp. nov. was collected from the Vathalmalai hills, which lies in the Eastern Ghats of India. This species heavily defoliates Curry Leaf Murraya koenigii during August to October. Myllocerus depressus sp. nov. was collected from southern states namely, Tamil Nadu, Karnataka, Telangana, and Andhra Pradesh. This species is found polyphagous in natures, feeding on different plants such as Pongamia, Water Apple, Cacao, Acacia sp., Jamoon, Mango, Sapota Manilkara zapota, Indian Raintree Albizia lebeck, Tulip Tree Liriodendron tulipifera, Lemon Citrus limon, Lucerne Medicago sativa, Sunflower Helianthus annuus, and ornamental plants. The number of Myllocerus species in India rises to 88 with the description of these two new species. There are many more weevil species waiting to be discovered, particularly under the genus Myllocerus, as they feed on a wide variety of plant species.

 

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References

 

Alonso-Zarazaga, M.A. & C.H.C. Lyal (1999). A world catalogue of families and genera of Curculionoidea (Insecta: Coleoptera) (excepting Scolytidae and Platypodidae). Entomopraxis, S.C.P., Spain, 315 pp.

O’Brien, C.W., M. Haseeb & M.C. Thomas (2006). Myllocerus undecimpustulatus undatus Marshall (Coleoptera: Curculionidae), a recently discovered pest weevil from the Indian Subcontinent. Entomology Circular No. 412, Division of Plant Industry, Florida Department of Agriculture and Consumer Services. 3 pp.

Lyal, C.H.C (2021). Glossary of Weevil Characters. International Weevil Community Website.  http://weevil.info/glossary-weevil-characters (accessed 27 on August2021).

Marshall, G.A.K (1916). Coleoptera. Rhynchophora: Curculionidae. In: Shiply, A.E. (ed.).  The Fauna of British India including Ceylon and Burma, Taylor and Francis, London, xv + 367 pp.

Oberprieler, R.G., A.E. Marvaldi & R.S. Anderson (2007). Weevils, weevils, weevils everywhere. Zootaxa 1668(1): 491–520. https://doi.org/10.11646/zootaxa.1668.1.24

Ramamurthy, V.V. & S. Ghai (1988). A study on the genus Myllocerus (Coleoptera: Curculionidae). Oriental Insects 22: 377–500.

Ramamurthy, V.V., B.P. Nathan & R.K. Anand (1992). Further taxonomic studies on Myllocerus with new synonymy of Hyperstylus (Coleoptera: Curculionidae). Oriental Insects 26: 119–152.

Schoenherr, C.J. (1823). Tabulasynoptica familiae Curculionidum. Isis von Oken 10: 1132–1146.