CHAETOTAXY OF THE , HOLMGREN (ISOPTERA: ) Part II. Worker

BY K. S. KUSnWAI-IA, M.Sc., PH.D., F.E.S.I. (Department of Zoology and Entomology, Rajasthan College of Agriculture, Udaipur) Received June 1, 1961

(Communicated by 3(. Ramchandra Rao, F,A,SC.)

CONTENTS

PAGE I. INTRODUCTION ...... 130

II. MATERIAL AND METHODS ...... 131

III. CH2ETOTAXY OF THE ORAL-APPENDAGES .. 131

IV. CHgETOTAXY OF THE THORACIC TERGITES .. 134 V. SUMMARY ...... 135

VI. ACKNOWLEDGMENTS ...... 136 VII. RE~RENCES ...... 136 VIII. ABBREVIATIONSUSED IN TEXT-FIGURES .... 136

I. INTRODUCTION IN Part I of this series (Kushwaha, 1960), the chcetotaxy of the soldier caste of the termite, Odontotermes (Odontotermes) assmuthi Holmgren (Sub- family: Macrotermitin~e) was discussed as compared with that of the soldier caste of two other allied species, namely, Odontotermes (Odontotermes) horni (Wasmann) and Odontotermes ( Odontotermes) obesus (Rambur) studied earlier by the author (Kushwaha, 1959; 1961 a, b, c) with reference to their taxonomic differentiation. The present account deals with a similar com- parative study of the cha~totaxy of the worker caste of Odontotermes (0.) assmuthi Holmgren from the taxonomic point of view and, as such, only such parts of the body as had proved to be of importance in this respect, viz., the oral appendages, and the thoracic tergites, have been taken up for consideration. 130 ChHtotaxy of the Termite, Odontotermes assmuthi Holmgren--H 131

A complete study of all the three castes of has been achieved so far, only in the case of Odontotermes (0.) obesus (Rambur)--the Common Mound-building Termite of India, of which a detailed, illustrated account has already been published elsewhere (Kushwaha, 1961 b).

II. MATERIAL AND METHODS 25-40 specimens of O. obesus were subjected to examination out of material collected by the author roundabout Dehra Dun (U.P.), ca. 610 metres above sea-level. In the case of O. assmuthi and O. horni, he is indebted to Dr. M. L. Roonwal, Director, Zoological Survey of India, Calcutta, for the provision of specimens bearing the following collection data:m O. assmuthi: Calcutta (ex from under a log of wood); 13-8-1957. O. horni: Calcutta suburbs (ex a dead but standing tree); 18-9-1957. The exact location of the bristles, as well as their general distribution on the various body-parts, was studied by means of an examination, under high magnification, of permanent preparations mounted on slides. All diagrams were drawn under camera lucida. In case any bristle was found missing, the position and size of its disc-like base was taken into account for purposes of study. Arabic numerals have been used to denominate the labral bristles, but in most other cases the bristles have been named after the particular parts of the body on which they occur.

III. CH2ETOTAXY OF THE ORAL-APPENDAGFS Variations in the number of bristles and their arrangement character- istic of the worker caste of each of the three species (vide supra) have been observed mainly in the regions of the labrum, the lacinia of maxilla, and the postmentum of labium, as detailed below:-- 1. Labrum (Text-Fig. 1, a-ci; lr.).--There are in O. assmuthi, as in O. obesus and O. horni, two pairs of apical labral bristles, consisting of an inner pairmthe true apicals (ap.), and an outer~the lateral apicals (ap.L). Posterior to the apicals, there are 3 pairs of large symmetrically placed bristles (1, 2, 3) distinctly differentiated from the rest, in O. assmuthi, whereas there are 3 or 4 such pairs in O. obesus, and four or five in O. horni. 2. Lacinia (Text-Fig. 1, d-f; Icn.).--In the workers of all the three species, as in the case of the soldiers, the lacinia is fringed along its inner margin with robust bristles--the lacinio-marginals--(lcnml.). Character- istically, a smaller number, only 9-10 bristles, is found in O, assmuthi, whcreas there are 11-13 (rarely 10) of them in O. obesus (vide Table I), and 12-13 in O. horni. There seems to be much variation in respect of the nmnber 132 K.S. KUSHWAHA

...--..... ;L 2"

~"a ,0.25mm.,"~"" ~/ ~ . 0"25mm.. ~. , 0"25mm. ,

/ ,

,

.... Ir.s. CI

TExT-FIe. 1. Labrum and maxilla, showing the characteristic bristles in workers of 3 spp. of Odantotermes (vide infra). 1. (Rambur) : (a) Labrum together with clypeal r~gion, showing 4 pairs of.bilatera!ly, symmetrical br!stles onthe labrum excluding the apical (ap.) and lateral apical (ap.l.) paJrs--alljomea with dottea lines, lne clypealpair (cll.) rose joined with dotted lines; (ai). Labrum, showing only 3 pairs excluding the apical and lateral apical pairs; (d) Lacinia, snowing, 12 laeinio-marginal bristles (lcnml.). 2. O.d?ntoterme8 horni (Wasmann): (b and bi). Labrum, snowing 4 tso.met.imes ?) pairs oI large taoral Oristles (1, 2, 3, 4) excluding the apical ana lateral apiEat oristles (joined with dotted lines); (e) Lacinia, showing 13 lacinto- marginal bristles. 3. Odontotermes assmuthi Holmgren: (c and ci) labrum, showing 3 pairs of bilaterally symmetrical bristles (1, 2, 3) excluding the apical and the lateral apical pairs (joined with dotted lines); (f) Lacinia, showing 9 lacinio.marginal bristles (lcnml.). Cha~totaxy of the Termite, Odontotermes assmuthi Holmgren--II 133 of bristles present in the left versus the right lacinia of workers as may be noted from Table I, as actually worked out in O. obesus. 3. Labium (Text-Fig. 2, a-ci; lb.).--It is only on the postmentum (pint.) that a few significantly differentiated bristles are noticeable.

g!

, , ,

~ ~, Uaj , prmt. / '

all ci

TI~T-FIO. 2. Labium, showing characteristic bristlos on the postmentum in workers of 3 spp. of Odontotermes (vide infra). (Wasmann): (a) Labium and (ai, aii) only postmontum, showing posterio.postmental bristles (ppmtl.) in particular, besides postmental (prntl. 1, pmtl. 2 ..... ore.) and medio.postmental pair (mpratl.) of bristles. Odontotermes obesus (Rambur): (b)Labium and (hi)only P0stmentum, showing only postmental (pmtl. 1, pmtl. 2, .... etc.) and medio.postmental pairs (mpmtL). Odontotermes assmuthi Holmgren: (c) Labium and (el) only postmentum, showing only postmental and medio-postmental pairs.

O. assmuthi resembles both O. obesus and O. horni, in possessing 3 or 4 characteristic bristles, the postmental bristles (pmtl. 1, pmtL 2, etc.), located latero-marginaUy on either side of the postmentum and a pair of conspicuous medially located bristles,--the medio-postmental pair (mpmtl.). In O. horni, there are, however, several additional bristles situated on the posterior mar- gin,--the posterio-postmentals (ppmtl. a.i and a.ii), which may serve to dis. tinguish it from the other two species, 134 K.S. KUSHWAHA

IV. CH~TOTAXY OF THE THORACIC TERGITES (Text-Fig. 3, a-cii)

o F'r-a-t , -- /pr a

/ " ~~. t)J " - ~I /,,_ /

, 0"25mm. , ~.t] ,l~v',~, "'X'V /~\/~\rnH'.l. O.t;mm

T~xT-FIO. 3. Thoracic tergites, showing characteristic bristles in worker of 3 spp. of Odontotermes (vide infta). Odontotermea assmuthi Holmgren:--(a) Pronotum, showing pro- noto.anlerior (pr.a.), pronoto-lateral (pr.L) and pronoto-poste~ior (pr.p.) pairs of bristles; (ai) Mesonoturn, showing mesonoto.lateral (mst.l.) and mesonoto-poateriot (mst.p.) pair of bristles; (aii) Metanotum, showing metanoto-lateral (mtt.l.) and metanoto-posteriot (mtt.p.) pair of bristles. Odontotermea obesus (Rambur) : (b, bi and bii) Pronotum, mesonotum and metanotum respectively, showing similar bristles as in O. asamuthi worker. Odontotermes horni (Wasmann): (c, ci and cii) Pronotum, mesonotum and metanotum respectively, showing undifferentiated bristles with denser distribution as compared to the other two species. O. assmuthi closely resembles O. obesus in the possession of 3 pairs of large, bilaterally symmetrical bristles on the pronotum, and 2 pairs each on the meso- and the metanotum as detailed below: Pronoturn (prt.) : Pronoto-anterior (pr.a.), pronoto-lateral (pr.L) and pronoto-posterior (pr.p.). Mesonotum (rnst.) : Mesonoto-lateral (mst.l.) and mesonoto-posterior (mst.p.), Chtetotaxy of the Termite, Odontotermes assmuthi Holmgren--H 135

Metanotum (mtt.) : Metanoto-lateral (mtt.l.) and metanoto-posterior (mtt.p.). TABLE I The number of Lacinio-marginal bristles found on the left versus the right lacinia of Worker individuals of Odontotermes (O.) obesus, based on an examination of 25 specimens

Serial No. of bristles found on No. of specimens No. lacinia~ of specimens showing each type of types of distribution of distribution Left versusRight of bristles

1 10 11 ! 2 11 11 4 3 11 12 3 4 11 13 1 5 12 10 1 6 12 11 7 7 12 12 4

8 13 12 3 9 14 13 1

In the case of O. horni, on the other hand, no such bristle differentiation is noticeable on the thoracic tergites. On the other hand, there appears to be a denser distribution of bristles in general than in the other two species. V. SUMMARY I. The presence of peculiarly differentiated bristles on certain oral appendages and on the thoracic tergites in the worker caste of Odontotermes (0.) assmuthi Holmgren, serving .to distinguish it from the workers of Odonto- termes (0.) obesus (Rambur) and Odontotermes (0.) horni (Wasmann) has been reported. 2. The labrum and the lacinia in O, assmuthi carry fewer bristles than in O. obesus and O. horni. 136 K.S. KUSHWAHA

3. On the labium, posterior-postmental bristles (ppmtl.) are absent both in O. assmuthi and in O. obesus, but are present in O. horni. 4. A few pairs of characteristic bristles are distinctly seen on the thoracic tergites in O. assmuthi as well as in O. obesus, but are not to be found in O. horni. VI. ACKNOWLEDGMENTS My sincere thanks are due to Dr. M. L. Roonwal, Director, Zoological Survey of India, Calcutta, for kindly providing material for study and for encouragement. I am also very grateful to Shri Y. Ramchandra Rao for valuable suggestions for improving the manuscript, and Dr. A. Rathore, Principal, Rajasthan College of Agriculture, Udaipur, for laboratory facilities provided. VII. REFERENCES Kushwaha, K.S. .. "Ch~totaxy of the soldier, worker and Mate of the termite, Odontotermes obesus (Rambur)," Curt. ScL, Bangalore, 1959, 28(10), 415-17. .. "Chmtotaxy of the termite, Odontotermes assmuthi Holmgren (Isoptera:Termitid~). Part I. Soldier," Prec. Ind. Acad. Sci., Bangalore, 1960, 52(2)B, 54-65. .. "Ch~totaxy of the termite, Odontotermes (Odontotermes) horni (Wasmann) (Isoptera: Termitid~). Soldier," Prec. 48th Indian Sci. Congr. (Roorkee, 1961), Calcutta, 1961 a, Part III, Abstracts, 427. .. "External morphology of the termite, Odontotermes obesus (Rambur). Part III. Cha~totaxy of the soldier, worker and alate castes," Rec. Indian Mus., Delhi, 1961 b, 56(4), 1958 (in press). .. "Taxonomic differentiation in three species of Odontotermes (Isoptera:Termitid~e) as based on ch~totaxy," Prec. UNESCO. International Symp. on Termites in Humid Tropics (Delhi, 1960), 1961 c (in press). VIII. ABm~,EVtATrONS USED IN TEXT-FmURES

ap., apical bristle of labrum. lb.p., labial palp. ap.L, apical lateral bristle of labrum. lb.s., labial suture. b.c.cd., basal condyle of cardo. lcn., lacinia. cd., cardo. lcnml., lacinio-marignal bristle. cl., clypeus. lgL, lingula (hyaline tip of labrum). cll., clypeal bristle. It., labrum. g., galea. lr.s., labral suture. gL, glossa. mpmtL, medio-postmental bristle, Ib,, labium, rest., mesonotum, Cha~totaxy of the Termite, Odontotermes assmuthi HolmgrenmH 137 mst.l.., mesonoto-lateral. ppmtl., postorio-postmontal bristle. mst.p., mcsonoto-posterior bristle. prt., pronotum. mtt., metanotum. pr.a., pronoto-anterior bristle. mtt.l., motanoto-lateral bristle. pr.l., pronoto-lateral bristle. mtt.p., mctanoto-postorior bristle. print., prementum. mx., maxilla. pr.p., pronoto-posterior bristle. mx.p., maxillary palp. st., stipes. pgl., paraglossa. su.g., sutural groove of stipcs. pmt., postmvntum; tm., torma (sclerite at the base of labrum). pmtl. 1, pmtl. 2, .... etc., postmental bristle I, 2, .... otc.