Corresponding author: Kirstin A. Williams (
Academic editor: P. Cerretti
Hybrids of
Williams KA, Villet MH (2014) Morphological identification of
The use of maggot debridement therapy (MDT) in South Africa has gained interest in the past decade (
Several identification keys have been produced either specifically for
A complicating factor is the known and widespread existence of natural hybrids of these species (
Twenty-four specimens of
Specimens previously identified by molecular markers (
Species | Specimen | Country of origin |
---|---|---|
|
C_EGT_01 | Egypt - Alexandria |
|
C_SA_BFN_01 | South Africa – Bloemfontein |
|
C_SA_BFN_02 | South Africa – Bloemfontein |
|
C_SA_BRT_01 | South Africa – Britstown |
|
C_SA_BRT_02 | South Africa – Britstown |
|
C_SA_DBN_12 | South Africa – Durban |
* |
C_SA_DBN_01 | South Africa – Durban |
* |
C_SA_DBN_06 | South Africa – Durban |
* |
C_SA_NEL_01 | South Africa – Nelspruit |
* |
C_SA_NEL_02 | South Africa – Nelspruit |
* |
C_THA_03 | Thailand – Chiang Mai |
* |
C_ZIM_02 | Zimbabwe – Matobos |
|
S_FRC_02 | France – Montferrier-Sur-Lez |
|
S_GER_01 | Germany – Kempen |
|
S_JPN_04 | Japan – Iwate |
|
S_NAM_01 | Namibia – Possession Island |
|
S_NAM_02 | Namibia – Possession Island |
|
S_SA_CT_01 | South Africa – Cape Town |
|
S_SA_CT_05 | South Africa – Cape Town |
|
S_SA_GHT_01 | South Africa – Grahamstown |
|
S_SA_GHT_02 | South Africa – Grahamstown |
|
S_SA_PTA_02 | South Africa – Pretoria |
|
S_SA_WTB_02 | South Africa – Witbank |
|
S_USA_01 | United States of America – Michigan |
A total of 18 distinguishing morphological characteristics of adults of
Published morphological characters used to distinguish specimens of
Character | Lucilia sericata | Lucilia cuprina | Analysis | |
---|---|---|---|---|
MDS | DFA | |||
|
||||
Number of paravertical setulae or occipital bristles ( |
Usually 2+2 but up to 8+8 (not always equal numbers i.e. can be 1+2 etc.) | 1+1 | yes | no |
Shape of postocular microtrichial pile on vertex (viewed obliquely from behind) ( |
Boundary between pale and dark areas not straight or sharply defined | Boundary straight and sharply defined | no | no |
Width of the frontal stripe (frontal vitta) ( |
Twice as wide as a parafrontal (fronto-orbital) plate | As wide as a parafrontal (fronto-orbital) plate | yes | yes |
Colour of the frontoclypeal membrane ( |
Light brown | Dark brown to black | yes | yes |
Second pair of presutural acrostichals ( |
Extend at least as far as insertions of the first pair of postsutural acrostichals | Do not extend to first pair of postsutural acrostichals | yes | no |
Number of setulae on ‘quadrat’ between discal setae and anterior margin of scutellum ( |
35–55 | 15–25 | yes | yes |
Bristles on the scutellum ( |
Dorsal bristles distinctly smaller than lateral hairs | Dorsal bristles slightly smaller than or equal to lateral hairs | no | no |
Number of hairs on the posterior slope of the humeral callus behind the basal setae ( |
6–8 | 0–4 | yes | yes |
Number of hairs on the edge of the notopleuron behind the posterior notopleural seta ( |
8–16 | 2–5 | yes | yes |
Metasternal area – sclerite midventrally between middle and hind coxae ( |
Hairy | Bare | no | no |
Colour of the fore femora ( |
Dark metallic blue to black or dark brown | Metallic green | yes | yes |
Contour of the last abdominal tergite ( |
Irregular depressions | Generally smooth | no | no |
|
||||
Distance between the outer and inner vertical setae of females ( |
Equal to 0.5–0.7 distance between prevertical and inner vertical setae | Equal to the distance between prevertical and inner vertical setae | yes | no |
Size of the angle formed by the inner vertical seta relative to the prevertical and outer vertical setae of females ( |
Obtuse | Right angle | yes | no |
Extent of metallic sheen on parafrontal sclerites of females ( |
From vertex barely to base of upper orbital seta and not enclosing bases of any frontal setae | From vertex almost to base of lower orbital seta and enclosing bases of 1 or 2 frontal setae | yes | yes |
|
||||
Shape of apical halves of cerci ( |
Broad and tapering | Slender and parallel | no | no |
Shape of apical halves of surstyli ( |
Curved and broad | Straight and slender | no | no |
Form of apical setae of cerci ( |
Long and wavy | Minute and straight | no | no |
Each specimen was scored against the 15 characters (
To explore the diagnosibility of the hybrids, a discriminant function analysis (DFA) was performed using PAST3 (
Paravertical setulae, distance between the outer and inner vertical setae, the size of the angle at the inner vertical triangle and extent of metallic sheen on parafrontal sclerites.
Frontal stripe –
Colour of the frontoclypeal membrane.
Number of setae on ‘quadrat’ between the anterior margin and discal setae on the scutellum.
Posterior slope of the humeral callus behind the basal setae and the posterior edge of notopleuron behind the posterior notopleural seta.
Superficially, the hybrid specimens were identified as
Non-metric Multi-Dimensional Scaling plot using a Manhattan distance metric using 11 characters. Light blue solid circles =
However, the ordination plot of the DFA (
Ordination plot of the first two roots of the discriminant function analysis using seven characters. Ellipses represent 95% confidence regions. Light blue solid circles =
Eigen vectors and values for the first two roots of the discriminant function analysis.
Character | Root 1 | Root 2 |
---|---|---|
Number of setulae on ‘quadrat’ demarcated by discal setae and anterior margin of scutellum |
|
0.0324 |
Number of hairs on edge of notopleuron behind posterior notopleural seta | 0.5576 | 0.3300 |
Number of hairs on posterior slope of humeral callus behind basal setae | 0.4216 |
|
Colour of fore femora | 0.2591 | -0.2023 |
Relative width of frontal stripe (frontal vitta) | 0.1551 | 0.0104 |
Extent of metallic sheen on parafrontal sclerites of females | 0.0519 | -0.0697 |
Colour of frontoclypeal membrane | -0.1551 | -0.0104 |
Eigenvalue | 18.5560 | 0.7406 |
Due to the greater number of female flies in the molecular study from which we chose our specimens, we did not include any males. Therefore the male genitalia characters are not discussed in detail. It is not possible to properly view the male genitalia without dissecting them and this is not ideal for non-entomologists such as medical doctors who are using these flies for MDT as one needs experience to dissect out the genitalia. It is possible to correctly identify these flies without using the male genitalia by using the other characters described in
The DFA unambiguously separated the
The introgressed and modern hybrids were not separated in the DFA ordination plot (
Introgressed and modern hybrids of
Four of the characters were consistently successful at separating
We thank Georg Goergen, Ashley Kirk-Spriggs, Nicky Lunt, Mervyn Mansell, Hideharu Numata, Cameron Richards, Kiyoshi Saigusa, Kabkaew Sukontason, Tarek Tantawi and Robyn Tourle for providing us with specimens, Emil von Maltitz for taking photographs. Funding was provided by the National Research Foundation (NRF) of South Africa. Any opinion, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Research Foundation.
Character-taxon matrix
Data type: Species data
Explanation note: Character-taxon matrix used in the MDS and DFA analyses