THE MORPHOMETRICAL VARIANCE AND ABUNDANCE OF Diplotaxodon SPECIES AROUND ...

110 Pages·2013·3.14 MB·English

by  Titus Phiri

The Pennsylvania State University
The Graduate School
College of Agricultural Sciences

REVIEW OF THE GENUS DIPLOTAXODON WITH A DESCRIPTION
OF TWO NEW SPECIES

A Thesis in
Wildlife and Fisheries Science
by
Titus Bandulo Phiri

© 2013 Titus Bandulo Phiri

Submitted in Partial Fulfillment
of the Requirements
for the Degree of

Master of Science

December 2013
The thesis of Titus Bandulo Phiri was reviewed and approved* by the following:

Jay R. Stauffer, Jr.
Distinguished Professor of Ichthyology
Thesis Adviser

Walter Tzilkowski
Associate Professor Emeritus of Wildlife

Wilson Lazaro Jere
Senior Lecturer of Fish Genetics

Jeremy Likongwe
Associate Professor of Fisheries Sciences

Michael G. Massina
Head and Professor
Department of Ecosystems Science and Management

*Signatures are on file in the Graduate School
ii
ABSTRACT
A review of the described species of the genus Diplotaxodon Trewavas 1935, deep water
(offshore) fishes endemic to Lake Malaŵi, was conducted and included the description of
two new species. Diplotaxodon spp. represent another example of the rapid radiation of the
Haplochromine species in Lake Malaŵi. Fishes were collected from Domira Bay and Senga
Bay. Morphometric and meristic differences among spp. were analyzed using Sheared
Principal Component Analysis (SPCA) for the morphometric data and Principal Component
Analysis (PCA) for the meristic data. To date seven species of Diplotaxodon are formally
described. The investigations from this study resulted into describing two new species which
were known by cheironym.

iii
TABLE OF CONTENTS
LIST OF FIGURES .......................................................................................................................... vi
LIST OF TABLES ............................................................................................................................ix
AKNOWLEDGEMENTS .................................................................................................................xi

CHAPTER 1 ..................................................................................................................................... 1
1.0.0 GENERAL INTRODUCTION ........................................................................................... 1
1.1.0 Study area ...................................................................................................................... 2
1.2.0 Study goals and objectives ........................................................................................................ 5
2.0.0 GENERAL METHODOLOGY ................................................................................................ 7
2.2.0 Collection of Fish Specimen.................................................................................................. 7
2.3.0. Data collection (Meristic and Morphometric) ....................................................................... 7
2.4.0 Meristic data ....................................................................................................................... 10
2.5.0 Data analysis ....................................................................................................................... 14
3.0.0 OVERVIEW OF THE GENUS Diplotaxodon TREWAVAS 1935 ...................................... 14
3.1.0 General Distribution of Diplotaxodon.................................................................................. 15
4.0.0 DESCRIBED SPECIES .......................................................................................................... 15
4.1.0 Diplotaxodon apogon Turner & Stauffer, 1998 ................................................................ 15
4.2.0. Diplotaxodon ecclesi Burgess & Axelrod, 1973 .............................................................. 19
4.3.0 Diplotaxodon macrops Turner & Stauffer, 1998 .............................................................. 20
4.4.0 Diplotaxodon aeneus Turner & Stauffer, 1998 ................................................................. 22
4.5.0 Diplotaxodon limnothrissa Turner, 1994 ........................................................................ 26
4.6.0 Diplotaxodon greenwoodi Stauffer &McKaye, 1986....................................................... 32
4.7.0 Diplotaxodon argenteus Trewavas, 1935 ........................................................................ 38
5.0.0. Overview of undescribed species........................................................................................ 45
CHAPTER 2 ................................................................................................................................... 47

6.0.0 DESCRIPTION OF TWO NEW SPECIES ......................................................................... 47
6.1.0. INTRODUCTION ................................................................................................................. 47
7.0.0 New species of Diplotaxodon .............................................................................................. 50
Diplotaxodon altus n. sp., n. nov (nova species, novem nomen) (Fig. 18)..................................... 50
Diplotaxodon sp. ‘deep’. .............................................................................................................. 50
7.1.0 Results ................................................................................................................................ 52
iv
8.0.0 Diplotaxodon maxillalongus n. sp., n. nov (nova species, novem nomen) (Fig. 18) ............. 67
Diplotaxodon sp. ‘maxillalongus’. ............................................................................................... 67
8.1.0 Results ................................................................................................................................ 70
9.0.0 Discussion .......................................................................................................................... 83
10.0.0 Conclusion ............................................................................................................................ 86

CHAPTER 3 ................................................................................................................................... 88
11.0.0 Dichotomous key for Diplotaxodon ....................................................................................... 88
13.0.0 Remarks............................................................................................................................ 92
LITERATURE CITED .................................................................................................................... 93

v
LIST OF FIGURES
Figure 1: Maps illustrating location of the study area, Lake Malaŵi showing Domira Bay and Senga
Bay in Salima District. Inset is map of Africa showing The Great Lift Valley Lakes and
location of Lake Malaŵi. (Source: Google earth and http://www.odci.gov/cia/publications) ..... 4
Figure 2: Diplotaxodon spp. showing landmarks and distances measured as indicated by the
numbered landmarks, the measured points not shown in the figure include orbital depth, cheek
depth, horizontal and vertical eye diameter. .............................................................................. 8
Figure 3: Illustration of counting of main external meristic sets of variables on dorsal spines, dorsal
rays, anal spines, anal rays and lateral line scales in black dots. .............................................. 10
Figure 4: Counting model for rays on pectoral-fin and pelvic-fin as part of the meristic variables. .... 11
Figure 5: Format for counting scales on the cheek, scales appear to form a pattern/ series were
considered as indicated by I, II, and III representing 3 series of scales .................................... 12
Figure 6: Part of the gill bar arch from the right hand side indicating how the gill rakers were counted
for epibranchial and ceratobranchial. ...................................................................................... 12
Figure 7: Diplotaxodon apogon, holotype from British Museum, described by Turner and Stauffer in
(1998). Holotype: BMNH 1996.4.30:21a ripe male of 87.8mm standard length (Source: Turner
and Stauffer 1998).................................................................................................................. 17
Figure 8: Plots of the sheared second principle components (morphological data) and the first factor
score, first principle component (meristic data) for Diplotaxodon apogon and Diplotaxodon
limnothrissa sampled from commercial vessel in Domira Bay, Lake Malawi in 2012 ............. 18
Figure 9: Diplotaxodon ecclesi described from a male holotype: USNM 210696 of 145.7mm standard
length, collected off Monkey Bay by Herbert R. Axelrod in 1973, redefined by Turner &
Stauffer 1998. Photo by Dr. Herbert R. Axelrod (Source://fishbase.org). ................................ 20
Figure 10: Diplotaxodon macrops, described from a ripe male holotype: BMNH 1996.4.30:1, with
106.7mm in standard length and was collected from 100m depth off Monkey Bay at 14o03′S
34o56′E by Turner in 1991. (Source: //wikipedia.org). ............................................................ 22
Figure 11: Diplotaxodon aeneus, described from a ripe male of 125mm standard length, holotype:
BMNH 1996.4.30:16, collected from a depth of 400m northeast of Nkhata Bay by ODA/SADC
pelagic Resource Project between 30 November 1993-December 1994 (source: Turner and
Stauffer 1998). ....................................................................................................................... 23
Figure 12: Freshly caught D aeneus (Photo: Martin J.Genner) ......................................................... 24
Figure 13: Male Diplotaxodon limnothrissa, at the beginning to develop breeding dress, Holotype
collected in 1991 is in the British Museum (Source:http://www.fishbase.org). ........................ 27
Figure 14: Plots of the sheared second principle components (morphological data) and the first factor
score, first principle component (meristic data) for Diplotaxodon greenwoodi and Diplotaxodon
limnothrissa sampled from commercial vessel in Domira Bay, Lake Malaŵi in 2012 ............. 31
Figure 15: Diplotaxodon greenwoodi specimen from Pennsylvania State University fish Museum
(Photo: Ad Connings). ........................................................................................................... 33
vi
Figure 16: Plots of the sheared second principle components (morphological data) and the first factor
score, first principle component (meristic data) for Diplotaxodon apogon and Diplotaxodon
greenwoodi sampled from commercial vessel in Domira Bay, Lake Malaŵi in 2012............... 37
Figure 17: Diplotaxodon argenteus, a benthopelagic fish species; (Photo source: malawicichlids.com)
.............................................................................................................................................. 39
Figure 18: Plots of the sheared second principle components (morphological data) and the first factor
score, first principle component (meristic data) for Diplotaxodon argenteus and Diplotaxodon
limnothrissa sampled from commercial vessel in Domira Bay, Lake Malaŵi in 2012 ............. 44
Figure 19: A fin clipped female Diplotaxodon altus from collected from Senga Bay, northeast of
Chipoka, Lake Malawi. (Photo: by Evance Samikwa 2013). ................................................... 51
Figure 20: Plots of the sheared second principle components (morphological data) and the first factor
score, first principle component (meristic data) for Diplotaxodon apogon and Diplotaxodon
altus sampled in Senga Bay and Domira Bay, Lake Malaŵi in 2012-2013 .............................. 56
Figure 21: Plots of the sheared second principle components (morphological data) and the first factor
score, first principle component (meristic data) for Diplotaxodon argenteus and Diplotaxodon
altus. ...................................................................................................................................... 59
Figure 22: Plots of the sheared second principle components (morphological data) and the first factor
score, first principle component (meristic data) for Diplotaxodon maxillalongus and
Diplotaxodon altus. ................................................................................................................ 62
Figure 23: Plots of the sheared second principle components (morphological data) and the first factor
score, first principle component (meristic data) for Diplotaxodon altus and Diplotaxodon
greenwoodi. ........................................................................................................................... 65
Figure 24: Plots of the sheared second principle components (morphological data) and the first factor
score, first principle component (meristic data) for Diplotaxodon altus and Diplotaxodon
limnothrissa ........................................................................................................................... 66
Figure 25: A female Diplotaxodon maxillalongus from collected from Senga Bay, northeast of
Chipoka. (Photo: by Evance Samikwa 2013). ......................................................................... 69
Figure 26: Part of the mouth showing the jaw arrangement and the teeth structure on the lower jaw . 69
Figure 27: Plots of the sheared second principle components (morphological data) and the first factor
score, first principle component (meristic data) for Diplotaxodon argenteus and Diplotaxodon
maxillalongus......................................................................................................................... 72
Figure 28: Plots of the sheared second principle components (morphological data) and the first factor
score, first principle component (meristic data) for Diplotaxodon maxillalongus and
Diplotaxodon greenwoodi. ..................................................................................................... 75
Figure 29: Plots of the sheared second principle components (morphological data) and the first factor
score, first principle component (meristic data) for Diplotaxodon maxillalongus and
Diplotaxodon limnothrissa. .................................................................................................... 78
Figure 30: Plots of the sheared second principle components (morphological data) and the first factor
score, first principle component (meristic data) for Diplotaxodon apogon and Diplotaxodon
maxillalongus......................................................................................................................... 81
vii
Figure 31: Diplotaxodon spp. with a juvenile fish in the mouth. ....................................................... 92

viii
LIST OF TABLES
Table 1: Morphometric measurements as a straight line joining two distinct points, 1-15 are related to
the standard length and the 16-23 are related to the head length, the measurements were used
for the sheared principal components analysis .......................................................................... 9
Table 2: Main meristic variable and codes used to collect and enter data, counting follows the order in
the table. ................................................................................................................................ 13
Table 3: Morphometrics of Diplotaxodon macrops (holotype and 19 paratypes), D. apogon (holotype
and 20 paratypes), D. aeneus (holotype and 5 paratypes), and D. ecclesi (holotype)
(source:Ichthyol. Explor. Freshwaters, vol.8 no. 3, pp. 239-252, 1998) ................................... 25
Table 4: Morphometric and meristic values of type series of Diplotaxodon limnothrissa (n= 23) with
mean, standard deviation and range of the population sampled from commercial vessel at
Domira Bay in 2012 ............................................................................................................... 27
Table 5: The Sheared principal components (PC2) and Unsheared Principle component (PC2)
variable loadings on size for D. greenwoodi and D. limnothrissa ............................................ 29
Table 6: The principle component analysis PC1 (meristic) and their standardized scoring coefficients
for D. greenwoodi and D. limnothrissa ................................................................................... 30
Table 7: Principal morphometric and meristic characteristics of Diplotaxodon greenwoodi (n=4 and
includes holotype). (Source: Proceedings of Biological Society of Washington 99(1), 1986, pp.
29-33) .................................................................................................................................... 34
Table 8: The Sheared principal components (PC2) and Unsheared Principle component (PC2)
variable loadings on size for D. greenwoodi and D. apogon.................................................... 35
Table 9: The Principle Component Analysis PC1 (meristic) and their standardized scoring
coefficients for D. greenwoodi and D. apogon ........................................................................ 36
Table 10: Morphometric and meristic values of type series of Diplotaxodon argenteus (n= 11) with
mean, standard deviation and range of the population including the holotye sampled from
commercial vessel at Domira Bay in 2012-2013 ..................................................................... 39
Table 11: The Sheared principal components (PC2) and Unsheared Principle component (PC2)
variable loadings on size for D. argenteus and D. limnothrissa. .............................................. 41
Table 12: The principle component analysis PC1 (meristic) variables and their standardized scoring
coefficients for D. argenteus and D. limnothrissa ................................................................... 42
Table 13: List of possible existing but undescribed species in the genus Diplotaxodon and their
taxonomic status .................................................................................................................... 45
Table 14: Morphometric and meristic values of type series of Diplotaxodon altus (n= 18) with mean,
standard deviation and range of the population including the holotype sampled from Senga Bay
and Domira Bay in 2012-2013 ............................................................................................... 52
Table 15: The Sheared principal components (PC2) and Unsheared Principle component (PC2)
variable loadings on size for D. altus and D. apogon. ............................................................. 54
Table 16: The principle component analysis PC1 (meristic) and their standardized scoring coefficients
for D. altus and D. apogon ..................................................................................................... 55
ix
Table 17: The Sheared principal components (PC2) and Unsheared Principle component (PC2)
variable loadings on size for D. altus and D. agenteus. ........................................................... 57
Table 18: The principle component analysis PC1 (meristic) variables and their standardized scoring
coefficients for D. altus and D. argenteus ............................................................................... 58
Table 19: The Sheared principal components (PC2) and Unsheared Principle component (PC2)
variable loadings on size for D. altus and D. maxillalongus. ................................................... 60
Table 20: The principle component analysis PC1 (meristic) variables and their standardized scoring
coefficients for D. altus and D. maxillalongus ........................................................................ 61
Table 21: The Sheared principal components (PC2) and Unsheared Principle component (PC2)
variable loadings on size for D. altus and D. greenwoodi. ....................................................... 63
Table 22: The principle component analysis PC1 (meristic) variables and their standardized scoring
coefficients for D. altus and D. greenwoodi ............................................................................ 64
Table 23: Morphometric and meristic values of type series of Diplotaxodon maxillalongus (n= 18)
with mean, standard deviation and range of the population including the holotye sampled from
Senga Bay and Domira Bay in 2012-2013 .............................................................................. 70
Table 24: The Sheared principal components (PC2) and Unsheared Principle component (PC2)
variable loadings on size for D. maxillalongus and D. greenwoodi ......................................... 72
Table 25: The principle component analysis PC1 (meristic) variables and their standardized scoring
coefficients for D. maxillalongus and D. apogon .................................................................... 74
Table 26: The principle component analysis PC1 (meristic) and their standardized scoring coefficients
for D. maxillalongus and D. limnothrissa ............................................................................... 76
Table 27: The principle component analysis PC1 (meristic) variables and their standardized scoring
coefficients for D. maxillalongus and D. limnothrissa ............................................................ 77
Table 28: The Sheared principal components (PC2) and Unsheared Principle component (PC2)
variable loadings on size for D. maxillalongus and D. apogon ................................................ 79
Table 29: The principle component analysis PC1 (meristic) variables and their standardized scoring
coefficients for D. maxillalongus and D. apogon. ................................................................... 80
Table 30: The adopted scientific classification (Linnaeus hierarchy) to which Diplotaxodon spp. were
described for the binomial nomenclature. ............................................................................... 91
x