Colomerus terminaliae, Sarkar, 2022

Sarkar, Sanjay, 2022, A new species of eriophyoid mites (Acari: Eriophyoidea) infesting Terminalia crenulata (Heyne) from sub-Himalayan region of India, Persian Journal of Acarology 11 (3), pp. 447-455 : 448-452

Colomerus terminaliae sp. nov. ( Fig. 1)

http://zoobank.org/ urn:lsid:zoobank.org:act:56DF0FAB-5ACC-465B-8D41-B28833A6E977

Female (n = 30) Body 159 (159–163) long, 47 (467–55) wide, worm like, white in color.

Gnathosoma – 16 (15–16) long, slightly curved down; dorsal pedipalp genual seta d absent; subepical pedipalp tarsal seta v 2 (1–2).

Prodorsal shield – 28 (28–29), 37 (37–38) wide; prodorsal shield subtriangular without shield lobe, prodorsal shield design shows two complete admedian lines broken at midpoint along its length, a short incomplete median line, two submedian lines, the right submedian line is broken whereas left summedian line is complete; dorsal tubercles near rear shield margin, 12 (12–13) apart, scapular seta sc 18 (18–19) and directed caudad.

Leg I – 34 (33–34); femur 8 (8–9), with basiventral femoral seta bv 7 (7–8); genu 4 (4–5) with antaxial genual seta l "14 (14–15), tibia 4 (4–5), with paraxial tibial seta l ' 4 (3–4); tarsus 6 (5–6); paraxial fastigial tarsal setae ft ' 6 (5–6), antaxial fastigial tarsal seta ft " 14 (13–14); paraxial unguinal tarsal seta u ' 2 (1–2), tarsal solenidion ω curved, knobbed and 5 (4–5), 4-rayed tarsal empodium em 5 (4–5).

Leg II – 30 (29–30) long; femur 8 (8–9) long, with basiventral femoral seta bv 7 (6–7); genu 4 (3–4) with antaxial genual seta l ″ 7 (6–7), tibia 4 (3–4), without paraxial tibial seta 1 ′; tarsus 5 (4–5) long, paraxial fastigial tarsal setae ft ′ 4 (3–4), antaxial fastigial tarsal seta ft ″ 16 (15–16), paraxial unguinal tarsal seta u ′ 2 (1–2), tarsal solenidion ω curved slightly knobbed 6 (6–7); 4-rayed tarsal empodium em 5 (4–5).

Coxae I – 13 (13–14) and contiguous basally; coxal surface smooth; 1b tubercles with seta present at the anterior margin of the coxa and seta 1b 8 (8–9); 1a tubercles with seta present above the line across the 2a tubercles; seta 1a 15 (14–15).

Coxae II – Smooth except one curved line in each just below the 2a tubercles and 10 (10–11), seta 2a 28 (28–29) long.

Opisthosoma – With equal number of microtuberculated dorsal and ventral semiannuli 57 (57– 58); large sized microtubercles elliptical in shape, located on annuli anterior margin; last 5 ventral annuli have micro striation, seta c2 19(18–19) on annulus 7 (7–8), seta d 37 (37–38) on annulus 18 (17–18); seta e 37 (37–38) on annulus 31 (31–32); seta f 18 (17–18) on annulus 51 (50–51); seta h1 absent, seta h2 43 (43–44).

Epigynum – 9 (9–10), 19 (18–19) wide and appressed to the coxae, 11 (10–11) longitudinal lines in 2 tiers; seta 3a 9 (8–9).

Male – Not observed.

Type Material

Holotype – Female (marked with a red label) on slide (no.1442/86/2019), India: West Bengal: Malda, Mongalbari, Latitude: 24° 50′ 47″ N and Longitude: 87° 55′ 48″ E, 24. xii. 2019 from Teminalia crenulata (Heyne) (Combretaceae) , Coll. S. Sarkar. Paratypes – 6 females on slide bearing holotype and 24 females on 4 slides (nos. 1443-1446/86/2019); collection data same as in holotype.

Differential diagnosis

So far 27 species are known under this genus including three from West Bengal, India ( Amrine et al. 2003, Chandrapatya et al. 2014). The new species closely resembles Colomerus alangii , and C. vitis , C. woodfordis , and C. trichodesmae in some morphological traits but can be distinguished from them by its unique morphological features ( Table 1).

The new species clearly differs from all other closely related species in having complete admedian lines in prodorsal shield and a short median line between two admedian lines. In other species of Colomerus , the region between admedian lines in prodorsal shield shows numerous broken lines. The distance between tubercles of sc setae is 12–13 apart in new species whereas it is 16–19 apart in other 3 species of Colomerus taken into consideration except C. vitis . In C. vitis tubercles of sc setae is 9–11 apart which is less than that of the new species. The new species also differs from C. vitis , C.alangii and C. trichodesmae in having elliptical or elongate microtuberles as all of the others have rounded microtubercles. Length of epigynum is 9 (9–10) in the new species but in other 3 species except C. vitis length of epigynum is greater and varies from 12–18. In C. vitis it is 8–9 long. On the basis of number of longitudinal scorings on epigynum, the new species differs from others as it has 11 scorings in two rows on its epigynum whereas other species have greater number of scorings (14– 16) on their epigynum. The new species and C. vitis show resemblance in the arrangement of longitudinal scorings in two distinct rows on epigynum whereas in other species of Colomerus these longitudinal scorings are not arranged in two distinct rows. The surface pattern of coxae I is smooth in C. tricohdesmae and in the new species but in other species, surface of coxae I is with fine dotted lines. Halawa et al. (2015) emphasized on the number of rays on tarsal empodium to classify the species of Colomerus on grape vine as he found this character was more or less fixed character (5–6 rays), but the new species has 4-rayed tarsal empodium. Colomerus trichodesmae also has 4-rayed tarsal empodium. In new species the length of seta d and seta e are of equal length whereas in other species they are unequal in length. The length of seta sc of new species is slightly longer than that of other species. Seta Ib and Ia of the new species are longer than that of C. vitis , C. trichodesmae and C. woodfordis , and almost equal to that of C. alangii . But at the same time, it differs from C. alangii in having slightly longer seta 2a. The host plant of the new species and its relation to the host is different from that of other closely related species. The damage symptoms produced to host plant by the new species is also different from that of other closely related species. The new species produces leaf rolling at leaf margin whereas C. vitis produces erineum on leaf, C. alangii produces yellowish green pouch gall on leaf, C. trichodesmae produces bead galls on both surfaces of the leaves and C. woodfordis produces ‘crowded buds’. As the eriophyoid mites are highly host specific ( Skoracka et al. 2010), the host plant specificity may be regarded as an important diagnostic tool for differential diagnosis of the species discussed here.

Relation to host

Mites are found along the leaf rolling at the edges. The mite produces deformities in the tender and matured leaves of the host plant. Leaves eventually become pale and fall off.

Etymology The specific epithet is derived from ‘ Terminalia ’ genus of the host plant.

Remarks

Colomerus terminaliae sp. nov. is new to Science and 28 th species within the genus Colomerus . This new mite belongs to the Class Acari of the Family Eriophyidae and is a potential pest of the economically important plant Terminalia crenulata commonly known as crocodile bark tree. This tiny plant feeder sucks nutrients from this plant and leaves become dry and pale. The dry leaves fall off eventually.

A point of interest of these mites, potentially much more serious than direct losses to agriculture and forestry, is that a few species are known to be vectors of certain viral diseases of different crop plants ( Slykhuis 1960). The transmission of 21 pathogens by 13 species of phytophagous mites to at least 34 plants has been reported in the literature ( Stephan et al. 2008). Most mite species that are known to vector plant pathogens are in the Eriophyidae . As a result of their tiny size and very short stylets they feed only the epidermal cells of their plant hosts where they may acquire and transmit disease agents to these plant cells ( Jones 1999). The basic necessity for the proper control or eradication of any harmful organism is to know its systematics as well as its degrees of damages inflicted on the host. In this regard, the eriophyoid mites are needed to understand in greater details particularly in India as the study of Indian eriophyoid is still at infant stage and most of the works are sparse and mainly on taxonomy. Therefore, it requires exploring the eriophyoid fauna through faunistic surveys all over the country on zonal basis and subsequently the relevant biology, ecology etc. of these economically important species.