Licneremaeus indicus, Arun & Ramani, 2020

Arun, A. & Ramani, N., 2020, Two remarkable new species of oribatid mites (Acari: Oribatida) from Acacia litter of Kerala, India, Zootaxa 4877 (3), pp. 539-558 : 550-556

Licneremaeus indicus sp. nov.

( Figs. 14–28 )

Diagnosis. Rostral tectum without areolae. Sensillus discoidal with fine barbs. Notogaster with elevations or bumps. At most 14 areolae present on the notogaster in dorsal view. Thirteen pairs of notogastral setae present. Porose areae Aa and A 2 present. Pygidium at the posterior end of notogaster. Epimeral setation: 2-1-3-1. Ventral plate fully areolate.

Measurements. Body length 101 (holotype), 98–103 (15 paratypes); body width 59 (holotype), 58–62 (15 paratypes).

Integument. Cuticle greyish brown in color. Body covered with abundant cerotegument in the form of small rounded granules. Microareolar patterns seen on notogaster, other than the 14 areolae.

Prodorsum ( Figs. 14 , 20–21, 23 ). Rostrum pointed apically. Lamellar (le, 8), rostral (ro, 10) and interlamellar (in, 8) setae simple, covered with granules/cerotegument and slightly curved. Length of setae le and ro shorter than the distance between the bases of their counterparts. Seta in inserted near to dorsosejugal suture, below the level of anterior tip of the notogaster. Bothridial cup widely open at the postero-lateral borders of prodorsum, sensillus (ss, 18), with clavate head and a short stalk, bearing thick, blunt spines. Transverse hump present in front of anterior most tip of dorsosejugal suture. Prodorsal surface bears chitinous lines. Seta le arises from the transverse ridge joining, two strong chitinous lines. Pedotectum I present, pedotectum II absent.

Notogaster ( Figs. 14 , 20, 22 , 24 ). Dorsosejugal suture highly convex, extending beyond interlamellar region and incomplete, being interrupted medially, towards the anteriormost portion. Notogaster cuneate anteriorly and oval posteriorly. Thirteen pairs of small, smooth, slightly curved setae present on notogaster, often covered with cerotegument giving a leaf like appearance. Setal length vary from 4–8 as the following; c 3, da (4); c 1, dm, dp, la (5); p 1, p 2, h 1, h 2, h 3 (6); lm (7); lp (8); c 2 and p 3 absent. Lyrifissures im, ip and ips present, im more or less horizontally placed between lm and lp; ip and ips visible in ventral view. Porose area Aa present closer to seta la; A 2 located posteriorly, above the level of seta h 2. An array of cuticular elevations and bumps present on notogaster. The first bump located at the region between setae da and c 1, surrounding an areolae; the second bump central in position, located between setae da and dm and it extends laterally on either sides, towards seta lm; the third bump located below the second one, curved and U-shaped, extending posteriorly, to slightly below the level of seta dp, encompassing an areolae. It extends laterally also on either side, as a transverse bump towards the insertion of seta lp. Three areolae present, between the field delimited by the bases of dm, la and lm. Apart from the above three areolae encompassed by the bumps, a single areola detected anteromedially on the notogaster, between setae c 1, of either side. Posterior border of notogaster produced in to a pygidium.

Gnathosoma ( Figs. 15 , 25 ). Chelicera (20) with small fixed and movable digits, seta cha (8) small and smooth, chb inconspicuous. Cheliceral teeth feebly developed. Trägardh’s organ (Tg) narrowly triangular. Mentum and submentum with wrinkles. Subcapitular setae h (5), m (6), a (4), or (2) smooth. Rutellum with three weakly developed dendrites. Palpal (24) surface striated.

Coxisternal region ( Figs. 15 , 26 ). With six pairs of short, smooth, and tapered epimeral setae (1a, 1b, 2a, 3a, 3b, and 4b), of approximately equal length. Epimeral setal formula 2-1-2-1 (4a absent). Epimeres I and II fused together and epimeres III and IV fused together and the fused epimeres delimited by apodemes. Coxisternal area margined by wrinkled ridges. Median depression seen on the fused epimeral plates, I and II as well as III and IV.

Ventral plate ( Figs. 15 , 27–28 ). Covered with polygonal sculptures, except the regions adjacent to the genital and anal apertures and the region between these two plates. Anterior border of genital plates broader than the posterior border and the anterior margin of each genital plate located next to the apodeme delimiting the epimeres III/IV. Genital plates bear less prominent wrinkles and five pairs of small, smooth setae of length ranging from 2–6; g 1 (6), g 2 (4), g 3 (3), g 4 (4) and g 5 (3). Aggenital seta (ag) absent, anal plates broader postero-laterally, slightly below the median level. Two pairs of anal setae (an 1 & an 2, 2–3) and two pairs of adanal setae (ad 1 & ad 2, 5–7) present, all setae small, smooth, seta ad 3 absent, ad 1 located posterior to the anal plate, ad 2 inserted laterally, slightly below the middle level of anal plate. Integument of anal plate not smooth, but with feebly developed elevated areas.

Legs ( Figs. 16–19 ). All legs tridactylous, with the median claw thicker than the lateral ones. Claws bear small spines, set dorsally and with longitudinal striations. Femora of all legs with wrinkles, other segments smooth. Chaetotaxy of legs including solenidia: leg I: 1-3-3(1)-3(1)-14(1), leg II: 1-3-1(1)-2(1)-12(1), leg III: 2-3-1-2-10, and leg IV: 1-2-0-3-10 (see Table 2).

Materials examined. Holotype and 15 paratypes collected from densely accumulated litter samples of A. auriculiformis , at the Calicut University Campus (11° 8’ 6.468’’ N 75° 53’ 18.5028’’ E), Malappuram (Dt.), Kerala, India, on 1.iv.2019, coll. Arun, A.

Type deposition. The holotype and ten paratypes are deposited in the collections of Zoological Survey of India , Western Ghat Regional Centre , Kozhikode , Kerala, India ; five paratypes are kept in the Acarology Collections , Division of Acarology , Department of Zoology, University of Calicut , Malappuram, Kerala, India .

Etymology. The species epithet, “ indicus ” is derived from the name of country from where the type specimens were collected, duly considering the status as being the first species of the Family Licneremaeidae , described from India.

Ecology. Large number of adults and various life stages of Licneremaeus indicus sp. nov. were found to inhabit the litter samples of A. auriculiformis . Hundreds of specimens were found to occupy all layers of litter samples, indicating their possible role in the degradation of highly recalcitrant Acacia litter.

Remarks. Licneremaeus indicus sp. nov., differs from all its congeners by the possession of 14 areolae on the notogaster, clavate sensillus, presence of three notogastral bumps encompassing one areola each and by the presence of cuticular ridges on the rostral tectum between setae le and ro. The new species shows most resemblance to the oriental species, L. licnophorus in the number of notogastral setae, presence of curved bump at the level of seta dp, and polygonal sculptures on the ventral plate. However, it is distinct from L. licnophorus in the presence of areolae between the field delimited by the bases of setae da and dm, clavate nature of sensillus (flattened sensillus in L. licnophorus ) and presence of pygidium on notogaster (absent in L. licnophorus ).

Figures

FIGURE 14. Licneremaeus indicus sp. nov., adult dorsal view. Scale bar 50 µm.

FIGURE 15. Licneremaeus indicus sp. nov., adult ventral view. Scale bar 50 µm.

FIGURES 16–19. Licneremaeus indicus sp. nov., adult; legs showing segments trochanter to tarsus, antiaxial view. 16. leg I, right; 17. leg II, right; 18. leg III, right; 19. leg IV, right. Scale bar 10 µm.

FIGURES 20–23. Licneremaeus indicus sp. nov., adult, SEM images. 20. dorsal view; 21. sensillus, lateral view; 22. notogastral seta; 23. prodorsum.

FIGURES 24–28. Licneremaeus indicus sp. nov., adult, SEM images. 24. lateral view; 25. subcapitulum; 26. Coxisternal region; 27. anal plate; 28. genital plate.