Insect Pest Management, A Current Scenario, 2011 (ed.), Dunston P. Ambrose,
Entomology Research Unit, St. Xavier’s College, Palayamkottai, India, pp.123-129.
123
LIN EAR REGRESSION COEFFICIEN T VALUES (R) OF POSTEMBRYON IC
DEVELOPMEN TAL MORPHOMETRY AS A TOOL IN THE BIOSYSTEMATICS OF
FOUR RHYN OCORIS SPECIES (HEMIPTERA: REDUVIIDAE: HARPACTORIN AE)
V. JEBA SINGH, S. JESU RAJAN AND DUNSTON P. AMBROSE*
Entomology Research Unit, St. Xavier’s College (Autonomous), Palayamkottai - 627 002,
Tamil Nadu, India.
email: eruxavier@gmail.com
ABSTRACT
Linear regression coefficient values (R) of postembryonic developmental morphometry of
head, cephalic appendages, thorax, thoracic appendages and abdomen of life stages of four
Rhynocoris species viz., R. fuscipes (F.), R. kumarii Ambrose and Livingstone, R. longifrons
(Stål) and R. marginatus (F.) were analysed. Twenty one such computed values were analysed
at two levels i.e., intraspecific and interspecific to find out the biosystematics utility, if any.
The affinity was calculated by identifying exact or closely related values. The values were
subjected to cluster analysis and a dendrogram was constructed and the similarity index was
calculated. The characters analysed exhibited similarity among the four Rhynocoris species,
unique characters in each species and closer affinity between R.kumarii and R. marginatus.
This model study suggests the biosystematics utility value of morphometry as a tool at intraand interspecies levels and the observations are discussed.
Key words: Linear regression coefficient values, postembryonic development morphometry,
biosystematics tool, Rhynocoris
Information regarding postembryonic
developmental characteristics of insects has been
used as a tool in the biosystematics of insects
(Daly, 1985 and Rohlf, 1990). Ambrose and
Ambrose (2003) studied the linear regression
coefficient (r) values of morphometry of various
parts of life stages of thirty species of reduviids
belonging to three major subfamilies namely
Harpactorinae, Reduviinae and Peiratinae to
explore the possibilities of utilising these values
as a tool in the biosystematics of Reduviidae.
Ambrose and Ambrose (2009) analysed 36
morphometric indices belonging to 27 species,
14 genera and 3 subfamilies viz., Harpactorinae,
Peiratinae and Reduviinae by direct observation
as well as unweighted pair group method using
arithmetic mean (UPGMA) incorporating
*
Corresponding author
Euclidean distances, Nei and Li’s genetic
distance coefficient and Jaccard’s coefficient
reveals diagnostic intra- as well as
intersubfamilial and generic affinities. Moreover,
it gives an insight into the placement of genera
in the existing divisions (tribes) of subfamilies
and their phylogenetic relationship. Further, it
clearly suggests a two diversified lines of
evolution of Peiratinae and Reduviinae from
Harpactorinae than the earlier suggested straight
line evolution of these two subfamilies from
Harpactorinae.
The present investigation explore the
biosystematics utility value of linear regression
coefficient values (r) of postembryonic
developmental morphometry of four species of
a harpactorinae reduviid genus Rhynocoris.
124
MATERIALS AND METHODS
MTL), 18. Prothoracic length/ Hind tibial length
(PTL/ HTL), 19. Prothoracic length/ Abdominal
The linear regression coefficient (r) values length (PTL/ AL), 20. Prothoracic length/
on the morphometry of life stages (I nymphal Abdominal width (PTL/ AW) and 21. Abdominal
instar to adult) of four Rhynocoris species length / Abdominal width (AL/AW) (Rukmani,
namely, R. fuscipes (F.), R. kumarii Ambrose and 1992; Das, 1996) (Table 1a and b).
Livingstone, R. longifrons (Stål) and R.
Cluster analysis was made using the
marginatus (F.) were calculated from the
morphometry data retrieved from the literature software in A MultiVariate Statistical Package
(Ambrose, 1987; 1996; 1999) and analysed from for Windows, ver. 3.1. A dendrogram was
constructed with Unweighted Pair Group Method
current work.
with Arithmetic Mean (UPGMA) clustering and
The measurement of one body part (a) was the similarity matrix index was calculated by the
compared to that of another (b) from the first per cent similarity coefficient (Kovach, 2007)
nymphal instar to the adult. Thus six pairs of (I, (Fig. 1).
II, III, IV, V nymphal instars and adult) (a) and
RESULTS AND DISCUSSION
(b) values were computed together and the
regression coefficient (r) was calculated for a
particular part. Equal number of males and 1. Head length/ Head width (HL/HW)
The (r) values are exactly similar (0.99)
females represented the adult measurement.
Twenty one such sets of values were computed among three species R. kumarii, R. longifrons
and the regression coefficient values were and R. marginatus, but slightly differs in R.
analysed to find out the biosystematics fuscipes (0.97).
significance, if any. Affinity was calculated by 2. Head length/ Prothoracic length (HL/PTL)
identifying exact values or relatively closer
Though the (r) values are exactly similar
values. The analysed sets of values include:
(0.83) in R. kumarii and R. marginatus but greatly
1. Head length/ Head width (HL/HW), 2.
Head length/ Prothoracic length (HL/PTL), 3.
Head length/ Abdominal length (HL/AL), 4.
Head length/ Diameter of eye (HL/DE), 5. Head
width/ Width between eyes (HW/WBE), 6. Head
width/ Prothoracic width (HW/PTW), 7. Entire
Antennal length/ Head length (EAL/HL), 8.
Entire Antennal length/ Prothorax length (EAL/
PTL), 9. Entire Antennal length/Foretibial length
(EAL/FTL), 10. Entire Antennal length/
Abdominal length (EAL/AL), 11. Rostral length/
Head length (RL/HL), 12. Rostral length/
Prothoracic length (RL/ PTL), 13. Rostral length/
Foretibial length (RL/ FTL), 14. Rostral length/
Abdominal length (RL/ AL), 15. Prothoracic
length/ Prothoracic width (PTL/ PTW), 16.
Prothoracic length/ Foretibial length (PTL/ FTL),
17. Prothoracic length/ Midtibial length (PTL/
it differs in R. fuscipes (0.76) and R. longifrons
(0.93).
3. Head length/ Abdominal length (HL/AL)
The (r) values are exactly similar in R.
kumarii and R. marginatus (0.96) and are almost
similar in R. fuscipes (0.87) and R. longifrons
(0.86).
4. Head length/ Diameter of eye (HL/DE)
The (r) values are exactly similar (0.99) in
all the four species viz., R. fuscipes, R. kumarii,
R. longifrons and R. marginatus.
5. Head width/ Width between eyes (HW/WBE)
The (r) values are exactly similar (0.98) in
R. kumarii, R. longifrons and R. marginatus but
it is slightly higher in R. fuscipes (0.99).
125
6. Head width/ Prothoracic width (HW/PTW) 14. Rostral length/ Abdominal length (RL/ AL)
The (r) values are similar in (0.98) R. fuscipes
The (r) values are closer among R. fuscipes
(0.88) and R. kumarii (0.86), but it much differs and R. kumarii but slightly greater in
in R. longifrons (0.90) and R. marginatus (0.83). R.marginatus (0.99) and lesser in R. longifrons
(0.97).
7. Entire Antennal length/ Head length (EAL/
HL)
15. Prothoracic length/ Prothoracic width
The (r) values are similar in R. kumarii and (PTL/ PTW)
R. marginatus (0.99) but it slightly differs in R.
The (r) values are exactly similar (0.99) in
longifrons (0.98) and R. fuscipes (0.96).
all the four species viz., R. fuscipes, R. kumarii,
8. Entire Antennal length/ Prothorax length R. longifrons and R. marginatus
(EAL/PTL)
16. Prothoracic length/ Fore tibial length
The (r) values are exactly similar in R. (PTL/ FTL)
fuscipes and R. kumarii (0.89) but it is lesser in
The (r) values are closer among R. kumarii
R. longifrons(0.88) and R. marginatus(0.86).
(0.87) and R. marginatus (0.89) but greater in R.
9. Entire Antennal length/Foretibial length
(EAL/FTL)
fuscipes (0.94) and R. longifrons (0.92).
17. Prothoracic length/ Midtibial length (PTL/
The (r) values are similar in R. kumarii and MTL)
R.marginatus (0.99) but it is lesser in R. fuscipes
The (r) values are closer among R. kumarii
(0.97) and R. longifrons (0.96).
(0.87) and R. marginatus (0.85), but slightly
10. Entire Antennal length/ Abdominal length greater in R. longifrons (0.90) and much greater
(EAL/AL)
in R. fuscipes (0.94).
The (r) values are similar (0.98) in R. kumarii 18. Prothoracic length/ Hind tibial length
and R. longifrons but it is lesser in R. fuscipes (PTL/ HTL)
(0.95) and R. marginatus (0.97).
The (r) values are exactly similar (0.88) in
11. Rostral length/ Head length (RL/HL)
R. kumarii and R. marginatus but slightly greater
The (r) values are similar (0.98) in R. in R. fuscipes (0.90) and much greater in R.
longifrons and R. marginatus slightly greater in longifrons (0.94).
R. kumarii (0.99) but much lesser in R. fuscipes 19. Prothoracic length/ Abdominal length
(0.92).
(PTL/ AL)
12. Rostral length/ Prothoracic length (RL/
PTL)
The (r) values are closer among in all the four
species viz., R. fuscipes (0.96), R. kumarii (0.95),
The (r) values are similar (0.89) in R. kumarii R. longifrons (0.93) and R. marginatus (0.94).
and R. longifrons but it is much greater in R.
20. Prothoracic length/ Abdominal width
fuscipes (0.94) and R. marginatus (0.91).
(PTL/ AW)
13. Rostral length/ Foretibial length (RL/ FTL)
The (r) values are exactly similar (0.98) in
The (r) values are exactly similar (0.99) in
all the four species viz., R. fuscipes, R. kumarii, R. kumarii and R. marginatus but much lesser in
R. fuscipes (0.90) and R. longifrons (0.92).
R. longifrons and R. marginatus.
126
21. Abdominal length / Abdominal width (AL/ Closer (r) values
AW)
1. R. fuscipes and R. kumarii have one closer (r)
The (r) values are exactly similar (0.98) in values i.e., in Head width/ Prothorax width (HW/
R. kumarii and R. longifrons but slightly lesser PTW).
in R. fuscipes (0.96) and greater in R. marginatus
2. R. fuscipes, and R. longifrons have five closer
(0.99).
(r) values i.e., Head length/ Abdominal length
Exactly similar (r) values
(HL/AL), Entire Antennal length/ Head length
(EAL/HL), Entire Antennal length/Fore tibial
1. All the four species of Rhynocoris viz., R.
length (EAL/FTL), Prothoracic length/ Hind
fuscipes, R. kumarii, R. longifrons and R.
tibial length (PTL/ HTL) and Prothoracic length/
marginatus have 3 similar (r) values i.e., in Head
Abdominal width (PTL/ AW).
length/ Diameter of eye (HL/DE), Rostral length/
Fore- tibial length (RL/ FTL) and Prothoracic 3. R. fuscipes and R. marginatus have 3 closer
length/ Prothoracic width (PTL/ PTW). Hence, (r) values i.e., Entire Antennal Length/
these values could be considered as generic Abdominal length (EAL/AL), Rostral length/
markers.
Prothoracic length (RL/ PTL) and Abdominal
length / Abdominal width (AL/AW).
2. R. fuscipes and R. kumarii have 2 similar (r)
values i.e., Entire Antennal length/ Prothorax 4. R. fuscipes, R. kumarii, R. longifrons and R.
length (EAL/PTL) and Rostral length/ marginatus have 3 closer (r) values i.e.,
Abdominal length (RL/ AL).
Prothoracic length/ Abdominal length (PTL/ AL),
Prothoracic length/ Foretibial length (PTL/ FTL)
3. R. kumarii, and R. longifrons have 3 similar
and Prothoracic length/ Midtibial length (PTL/
(r) values i.e., Entire Antennal length/ Abdominal
MTL).
length (EAL/AL), Rostral length/ Prothoracic
length (RL/ PTL) and Abdominal length / 5. R. longifrons and R. marginatus have 2 closer
Abdominal width (AL/AW).
(r) values i.e., Entire Antennal length/ Prothorax
length (EAL/PTL) and Rostral length/
4. R. kumarii and R. marginatus have 6 similar
Abdominal length (RL/ AL).
(r) values i.e., Head length/ Prothoracic length
(HL/PTL), Head length/ Abdominal length (HL/ Cluster analysis
AL), Entire Antennal length/ Head length (EAL/
The dendrogram (Fig.1) of linear regression
HL), Entire Antennal length/Foretibial length
coefficient values (r) of postembryonic
(EAL/FTL), Prothoracic length/ Hind tibial
developmental morphometry constructed with
length (PTL/ HTL) and Prothoracic length/
UPGMA clustering revealed interspecific
Abdominal width (PTL/ AW).
relationships among four Rhynocoris species
5. R. kumarii, R. longifrons and R. marginatus with highest similarity in HL/DE, RL/ FTL and
have 2 similar (r) values i.e., Head length/ Head PTL/PTW (100%); EAL/HL and AL/AW
width (HL/HW) and Head width/ Width between (99.87%); HW/WBE and RL/AL (99.61%);
eyes (HW/WBE).
EAL/AL and RL/HL (99.35%); PTL/FTL and
PTL/MTL (99.16 %); HW/PTW and EAL/PTL
6. R. longifrons and R. marginatus have one
(98.71%) and HL/AL and PTL/AW (98.25%).
similar (r) values i.e., Rostral length/ Head length
(RL/HL).
The analysis of linear regression coefficient
values (r) of postembryonic developmental
127
morphometry of four Rhynocoris species can be
used as a tool for generic identity and
interspecific differentiation and affinity. For
instance, three exactly similar (r) values viz., HL/
DE, RL/FTL and PTL/PTW could be considered
as Rhynocoris generic markers. R. kumarii and
R. marginatus are more closer with six similar
values showing greater affinity among the four
Rhynocoris species. From this group R. kumarii
exhibits greater affinity to R. marginatus with
six similar values. The affinity between R.
kumarii and R. longifrons with three similar
values is greater than that between R. fuscipes
and R. kumarii with two similar values. Three
species viz., R. kumarii, R. longifrons and R.
marginatus share affinity among them with two
similar values. Thus R. fuscipes distinguishes
itself from the other three Rhynocoris species.
R. longifrons and R. marginatus also have
separate affinity with one similar value. R.
fuscipes has unique RL/HL character and differs
from the other three Rhynocoris species and R.
fuscipes and R. longifrons also has unique HL/
PTL character and differs from the other two
Rhynocoris species.
CONCLUSION
The analysis of linear regression coefficient
values (r) of postembryonic developmental
morphometry of four Rhynocoris species
revealed that the following three characters HL/
DE, RL/FTL and PTL/PTW could be considered
as Rhynocoris generic markers. Those characters
confirmed by the dendrogram showed in 100 %
similarity among the four Rhynocoris species.
The morphometry showed greater affinity
between R. kumarii and R. marginatus among
the four Rhynocoris species. This affinity was
also confirmed by dendrogram node of grouped
characters in HL/AL and PTL/AW showed in
98.25% similarity in R. kumarii and R.
marginatus (Fig. 1).
The above said analysis of linear regression
coefficient values (r) of postembryonic
developmental morphometry suggests its utility
as a biosystematics tool at generic and species
levels. However, the sample size taken for the
present study is inadequate. Hence, further
studies with more number of species and genera
from different subfamilies are imperative to
realize the multidisciplinary facts of
biosystematics
with
postembryonic
developmental morphometry as a tool.
Figure 1. Phylogenetic affinity among four Rhynocoris species based on postembryonic
developmental morphometry regression coefficient (r) values analysed by UPGMA clustering
method (per cent similarity coefficient).
128
Table 1a. Linear regression coefficient values (r) of postembryonic developmental morphometry of four Rhynocoris species (contd.).
STAGE
HL/HW
HL/PTL
HL/AL
HL/DE
HW/WBE HW/PTW EAL/HL
EAL/PTL EAL/FTL EAL/AL
R. fuscipes
0.97
0.76
0.87
0.99
0.99
0.88
0.96
0.89
0.97
0.95
R. kumarii
0.99
0.83
0.96
0.99
0.98
0.86
0.99
0.89
0.99
0.98
R. longifrons
0.99
0.93
0.86
0.99
0.98
0.90
0.98
0.88
0.96
0.98
R. marginatus
0.99
0.83
0.96
0.99
0.98
0.83
0.99
0.86
0.99
0.97
Table 1b. Linear regression coefficient values (r) of postembryonic developmental morphometry of four Rhynocoris species.
STAGE
RL/HL RL/PTL RL/FTL RL/AL PTL/PTW PTL/FTL
PTL/MTL PTL/HTL PTL/AL PTL/AW AL/AW
R. fuscipes
0.92
0.94
0.99
0.98
0.99
0.94
0.94
0.90
0.96
0.90
0.96
R. kumarii
0.99
0.89
0.99
0.98
0.99
0.87
0.87
0.88
0.95
0.98
0.98
R. longifrons
0.98
0.89
0.99
0.97
0.99
0.92
0.90
0.94
0.93
0.92
0.98
R. marginatus
0.98
0.91
0.99
0.99
0.99
0.89
0.85
0.88
0.94
0.98
0.99
129
ACKNOWLEDGEMENTS
Ambrose, A.D. and Ambrose, D.P. 2003 Linear regression
coefficient (r) of postembryonic developmental
morphometry as a tool in the biosystematics of
Reduviidae. (Insecta: Hemiptera). Shaspha, 10(1):
57-66.
The authors are grateful to the authorities of
St. Xavier’s College, Palayamkottai for facilities.
One of us (DPA) thank Council of Scientific and
Industrial Research (R.No.37(1310)/07/EMR-II) Ambrose, A.D. and Ambrose, D.P. 2009. Morphometric
indices in the biosystematics of Reduviidae (Insecta:
and University Grants Commission (F.No.33Hemiptera). Indian Journal of Entomology, 71(1):
330/2007(SR)) New Delhi for financial
18-28.
assistance.
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