Rinacapritermes Amina & Rajmohana, 2022

Amina, Poovoli, Rajmohana, Keloth, Dinesh, K. P. & Asha, Gopalan, 2022, Integrative taxonomic studies on Rinacapritermes Amina & Rajmohana, n. gen. (Blattodea: Isoptera: Termitidae) with two new species from India, Zoosystema 44 (3), pp. 109-124 : 111-121

Genus Rinacapritermes Amina & Rajmohana , n. gen.

urn:lsid:zoobank.org:act:8C629647-1999-45D7-BAB7-F16A1C792D1C

TYPE- SPECIES. — Rinacapritermes silvius Amina & Rajmohana , n. sp.

MORPHOLOGICAL DIAGNOSIS. — Soldier. Soldiers with antennae 15 segmented, labrum with substraight anterior margin equipped with broad-based, robust and long antero-lateral points. Frons sharply inclining in front, fontanelle transverse and frontal gland large, postmentum club-shaped, pronotum saddle-shaped, anterior margin convex, without notch.

Worker. Worker caste with 14-15 segmented antennae and mandibles with apical tooth slightly larger than first marginal. Second marginal of left mandible not distinct, third marginal rudimentary or just as an impression of tooth, not separated from first marginal by any cut or notch; small, tooth-like process partially visible on the underside of the left molar plate. Digestive tube characterised by the presence of a mixed segment and the absence of malpighian nodule, with both pairs of malpighian tubules united at common base. Enteric valve cushions acutely triangulate and median longitudinal area of each cushion with uniformly distributed small spine-like protrusions ( Fig. 3E ).

DNA BARCODE DIAGNOSIS. — A total of 28 mt COI sequences were generated from the Western Ghats representing multiple species under nine genera for the first time ( Appendix 1). On the preliminary phylogenetic tree multiple sequences of monophyletic group representing at least two species is treated as a new genus Rinacapritermes Amina & Rajmohana , n. gen. with an unresolved sister relationship among the other genera of the larger ‘ Termitinae clade’ ( Fig. 4 ). Members of the Rinacapritermes Amina & Rajmohana , n. gen. is genetically distinct from the morphologically similar genus Indocapritermes ( Fig. 4 ). The new genus exhibited a high-level genetic divergence of 10.7% to 13.7%, for mt COI with the genus Indocapritermes ( Appendix 3).

ETYMOLOGY. — The genus name ‘ Rinacapritermes ’, is the combination of name ‘Rina’ and ‘capritermes’. ‘Rina’ refers to the first author’s daughter and ‘capritermes’ refers to the morphological similarity with Capritermes Wasmann, 1897 group.

GEOGRAPHICAL DISTRIBUTION ( Fig. 5 ). — The Western Ghats from Wayanad, Kozhikode, Ernakulam, Idukki and Kottayam districts (Kerala state, India).

BIOECOLOGY. — Rinacapritermes Amina & Rajmohana , n. gen. species are soil dwellers. All samples in the present study were collected from underneath small boulders. The concavity and the rudimentary ridges of the molar plate of right mandible of worker caste ( Figs 1F ; 2F ) indicate their humus/organic rich soil feeding habit of type III feeding group ( De Souza & Brown 1994). The soldier abdomen has a hyaline appearance, indicating that they are fed with salivary secretions only ( Scheffrahn et al. 2017). Since they are not wood feeders, they are not categorised as pests. Their presence in multiple localities ranging from low (26 m asl.) to high elevations (910 m asl) indicates that they do not have any strict elevational preferences. Among the two species, the samples of R. silvius Amina & Rajmohana , n. gen., n. sp. were collected from the forest area while R. abundans Amina & Rajmohana , n. gen., n. sp. from tea and rubber plantations.

DESCRIPTION

Imago

Not known.

Soldier

Head capsule. Monomorphic, small; head moderately and body fairly hairy. In dorsal view head subrectangular; broad; antero-lateral corners of head rounded, without any tuberclelike process. Frontal gland large and median arm of Y-suture distinct only at posterior part of head capsule; in profile, frons sharply inclining in front; fontanelle transverse. Antennae with 15 segments. Labrum not swollen; asymmetrical, anterior margin substraight with broad based, robust and long antero-lateral points or spine-like processes. Mandibles asymmetrical and thick; left mandible strongly twisted at middle, with blunt apex, tip without any hook, not beak-like; basal projection sharply pointed. Right mandible blade-like with pointed apex, facing upwards; inner margin of right mandible incurved at middle region and with a deep cut at basal half; postmentum club-shaped.

Pronotum. Saddle-shaped; anterior lobe raised, narrower and smaller than posterior lobe; anterior margin convex; posterior margin substraight; anterior and posterior margin without any notch. Mesonotum and metanotum narrower than pronotum. Legs with 3:2:2 apical tibial spurs; dorsal spur of foretibia sometimes indistinct; tarsi 4-segmented.

Worker

Head capsule. Monomorphic; head and body densely hairy. In dorsal view head subcircular, maximum width of head capsule at base of antennae. Fontanelle plate translucent and round. Antennae with 14-15 segments. Postclypeus swollen.

Left mandible. Apical tooth slightly larger than first marginal. Posterior margin of apical tooth concave; second marginal not distinct (M2); third marginal rudimentary (M3) or just as an impression of tooth, not separated from first marginal by any cut or notch; small, tooth-like process partially visible on the underside of the left molar plate; molar plate large and extending upto first marginal.

Right mandible. Apical tooth finger-like and larger than first marginal (M1); posterior margin of first marginal a little longer than anterior margin; second marginal (M2) short and with incurved posterior margin; molar plate longer than posterior margin of second marginal, without any ridges; cockroach notch present.

Pronotum. Saddle-shaped. Legs with 3:2:2 apical tibial spurs, dorsal spur sometimes absent or indistinct; fore tibia swollen.

Digestive tube ( Fig. 3 A-D). Crop (C) globose, voluminous and partially visible in dorsal view in coiled condition, funnelling into a poorly sclerotized gizzard. Mixed segment (MS) present. Both pairs of malpighian tubules united at common base; malpighian nodule absent. First part of proctodeal segment (P1) starting from the right side of abdomen, tubular and short. Posterior part narrow and running into paunch (P3) through narrow enteric valve (P2). P2 inserted into paunch (P3). Paunch J-shaped, composed of 2 parts. Region of attachment of enteric valve remaining separated by constriction. Posterior part of paunch narrowing progressively and opening into long and narrow tube-like colon with a U-turn at anterior side and P4 leading to very large bulbous rectum (P5).

Enteric valve armature ( Fig. 3E ). Thin, composed of six acutely triangulate cushions; acute points of cushions directed to posterior. Median longitudinal area of each cushion covered with uniformly distributed and small spine-like protrusions. Each cushion separated by cuticular lining having similar but larger and more widely spaced protrusions.

REMARKS

In the key to Indian genera of Termitinae ( Chhotani 1997) , the proposed new genus runs to serial number 17, leading to Indocapritermes . In the key to common genera of Termitidae found in South India ( Kalleshwaraswamy et al. 2013), this genus also keys to Indocapritermes , at serial number 9. However, it does not fit the description of Indocapritermes . The soldiers of Rinacapritermes Amina & Rajmohana , n. gen. have antennae with 15 segments vs 14 segments in Indocapritermes ; anterior margin of labrum is substraight with broad based, robust and long, antero-lateral points in the new genus vs labrum with narrow based, short, thin and minute lateral points in the latter; comparing to head length, left mandible of new genus is somewhat longer, thinner and tip not broadly rounded vs shorter, thick with broadly rounded tip; apical blade of right mandible pointed and facing upwards in Rinacapritermes Amina & Rajmohana , n. gen. ( Fig. 7C ) vs not much pointed and substraight in Indocapritermes ( Fig. 7D ). Anterior lobe of pronotum in new genus is slightly raised with strongly convex anterior margin and without any notch vs anterior lobe not raised with slightly convex to substraight anterior margin and with a weak median notch in latter; posterior margin substraight, not emarginate and without any notch in proposed new genus vs slightly convex, faintly emarginate and with a weak notch. The workers also differ in having antennae with 14-15 segments in the new genus vs 13-14 segments in Indocapritermes ; a small, tooth-like process partially visible on the underside of the left molar plate in new genus, while this tooth-like process is absent in Indocapritermes . The shape of the antero-lateral points of labrum in soldier caste also help to separate this genus from the rest of other genera under Pericapritermes -group found in India ( Fig. 6 )

The proposed new genus has the posterior margin of the right second marginal of the worker mandible (M2) incurved ( Figs 1F ; 2F ), the digestive gut without a malpighian nodule and P1 is short and tubular, as seen in Pericapritermes -group ( Noirot 2001; Krishna et al. 2013). Hence based on the worker mandible structure and the gut morphology, Rinacapritermes Amina & Rajmohana , n. gen. is placed in Pericapritermes - group, though their soldiers are with 15 segmented antennae, in spite of their usual 14 segments.

. Acknowledgements

KEY TO THE SPECIES OF RINACAPRITERME S AMINA & RAJMOHANA, N. GEN.

— Comparatively smaller: Head length to the base of mandibles 1.48-1.55 mm; maximum head width 1.06- 1.10 mm. Postmentum short and a little wider at waist (postmentum length 0.71-0.79 mm; postmentum contraction index 0.48-0.54 mm) ................. Rinacapritermes abundans Amina & Rajmohana, n. gen., n. sp.

— Comparatively larger: Head length to the base of mandibles 1.60-1.66 mm; maximum head width 1.17-1.24 mm. Postmentum long and a little narrower at waist (postmentum length 0.85-0.89 mm; postmentum contraction index 0.39-0.45 mm) ......................................... Rinacapritermes silvius Amina & Rajmohana , n. gen., n. sp.

Figures

FIG. 3. — Digestive tube of Rinacapritermes silvius Amina & Rajmohana,n. gen., n. sp. worker:A, dorsal view; B, left lateral view; C, right lateral view; D, ventral view; E, worker’s enteric valve armature. Scale bars: A-D, 0.5 mm; E, 20 μm.

FIG. 4. — Maximum likelihood tree based on 663 bp of mitochondrial COI gene (*represents the bootstrap values above 50%).

FIG. 5. — Distribution map of Rinacapritermes Amina & Rajmohana, n. gen. species.

FIG. 1. — Rinacapritermes silvius Amina & Rajmohana, n. gen., n. sp.: A, soldier body dorsal view; B, soldier head dorsal view; C, soldier head profile; D, soldier’s labrum; E, soldier’s postmentum; F, worker left and right mandible. Scale bars: A, B, 0.5 mm; C, F, 0.3 mm; D, 0.1 mm; E, 0.2 mm.

FIG. 2. — Rinacapritermes abundans Amina & Rajmohana,n. gen., n. sp.: A, soldier body dorsal view; B, soldier head dorsal view; C, soldier head profile; D, soldier’s labrum; E, soldier’s Postmentum; F, worker left and right mandible. Scale bars: A, 0.5 mm; B, F, 0.3 mm; C, 0.2 mm; D, E, 0.1 mm.

FIG. 7. — A, pronotum of Rinacapritermes silvius Amina & Rajmohana,n. gen.,n. sp. soldier; B, pronotum of Indocapritermes aruni Chhotani,1997 soldier C, mandible of Rinacapritermes abundans Amina & Rajmohana, n. gen., n. sp. soldier D, mandible of Indocapritermes aruni soldier. Scale bars: 0.2 mm.

FIG. 6. — Labrum of genera under Pericapritermes-group;A, Dicuspiditermes incola (Wasmann,1893); B, Homallotermes pilosus (Mathur & Thapa,1962); C, Indocapritermes aruni Chhotani,1997;D, Krishnacapritermes maitii Chhotani,1997;E, Labiocapritermes distortus (Silvestri,1922);F, Pericapritermes dunensis (Roonwal & Sen-Sarma, 1960); G, Procapritermes keralai (Chhotani & Ferry, 1995); H, Pseudocapritermes fletcheri (Holmgren & Holmgren, 1917). Scale bars: A-C, 0.3 mm; D, E, H, 0.2 mm; F, G, 0.1 mm.