Seek, and ye shall find – the example of Neohydrotaea lundbecki (Michelsen) (Diptera: Muscidae), a rare muscid species or just ignored so far in forensic entomology?

Abstract

Neohydrotaea lundbecki (Michelsen) is a muscid species considered rare as known only from four specimens reported so far from Denmark and Great Britain. Five females of the species were collected during a surveillance study of necrophagous insects active in flight in June 2009 and June 2010 in Germany. It is the first record of N. lundbecki from Germany and the first report since the last documented finding of the species in 1968. We discuss this event in the light of quality assurance in forensic entomology and the ability of experts and researchers to identify relevant taxa at the genus or species level by using keys designed for the identification of forensically important Diptera, especially. The present example should make researchers more sensitive to the importance of surveillance studies, looking for hidden species by different tools and to complete the list of potential taxa which could be present on a corpse.

Full text

NORTH-WESTERN JOURNAL OF ZOOLOGY 12 (1): 196-198 ©NwjZ, Oradea, Romania, 2016
Article No.: e152201 http://biozoojournals.ro/nwjz/index.html
Seek, and ye shall find – the example of Neohydrotaea lundbecki
(Michelsen) (Diptera: Muscidae), a rare muscid species or just ignored
so far in forensic entomology?
Andrzej GRZYWACZ1*, Jens AMENDT2 and Heike FREMDT2
1. Chair of Ecology and Biogeography, Nicolaus Copernicus University, Lwowska 1, 87-100 Toruń, Poland
2. Institute of Forensic Medicine, Goethe-University Frankfurt, Kennedyallee 104, D-60596 Frankfurt am Main, Germany
*Corresponding author, A. Grzywacz, Tel. 0048 56 611 26 49, E-mail: hydrotaea@gmail.com
Received: 02. December 2014 / Accepted: 12. June 2015 / Available online: 30. May 2016 / Printed: June 2016
Abstract. Neohydrotaea lundbecki (Michelsen) is a muscid species considered rare as known only from four
specimens reported so far from Denmark and Great Britain. Five females of the species were collected during
a surveillance study of necrophagous insects active in flight in June 2009 and June 2010 in Germany. It is the
first record of N. lundbecki from Germany and the first report since the last documented finding of the species
in 1968. We discuss this event in the light of quality assurance in forensic entomology and the ability of
experts and researchers to identify relevant taxa at the genus or species level by using keys designed for the
identification of forensically important Diptera, especially. The present example should make researchers
more sensitive to the importance of surveillance studies, looking for hidden species by different tools and to
complete the list of potential taxa which could be present on a corpse.
Key words: Diptera, Muscidae, Neohydrotaea lundbecki, new record, forensic entomology.
Legal case investigations and carrion succession
experiments have hitherto revealed association of
numerous arthropod species with decomposing
remains of human and animal origin. Manual
sampling and surveillance studies using baited
traps help to determine spatial and temporal pref-
erences of forensically relevant species (Hwang &
Turner 2005; Fremdt & Amendt 2014) and to col-
lect material for both faunistic (Prado e Castro et
al. 2010) and systematic approaches (Domínguez
& Aballay 2008). Some rare dipteran species, e.g.
Thyreophora cynophila (Panzer) (Martín-Vega et al.
2010) and Fannia conspecta Rudzinski (Grzywacz &
Prado e Castro 2012) have been recorded in such
studies. Our knowledge on the biology and the
morphology, at least of the immature stages, of
many carrion visiting taxa is still scanty, and often
are considered only as accidental invaders, not
ovipositing on cadavers (Matuszewski et al. 2008).
Nevertheless it remains unclear if an occurrence of
juvenile stages is just hidden by a probably low
number of specimens and the difficulty to separate
them from better known taxa or if those taxa really
do not colonise a cadaver. Recently, Fremdt et al.
(2012) showed that such a rare taxa, the blow fly
Lucilia silvarum Meigen, which has been ignored in
important forensic keys (Smith 1986; Szpila 2010),
colonises human cadavers.
Neohydrotaea lundbecki (Michelsen) is a rare
species hitherto found at one locality in Denmark
(Michelsen 1978) and two in Britain (Pont et al.
1994). Furthermore the only known specimens of
this taxon are three males and just one female.
Originally described in the monotypic genus Cryp-
tophyra Michelsen, Pont (1986) synonymised it
with Hydrotaea Robineau-Desvoidy. Savage &
Wheeler (2004) revealed a sister-group relation-
ship between Hydrotaea and Neohydrotaea Malloch
and boundaries of the latter group were expanded
by the authors.
We trapped flies from September 2008 to May 2011 in five
locations in and close to Frankfurt am Main, Germany.
Beneath two urban and one suburban habitat, traps were
placed at a semi-natural and a rural site, representing a
typical German mixed forest dominated by beeches. Ap-
proximately 500 µl dimethyl trisulfide and 10 g beef liver
were used as bait (for details see Fremdt & Amendt 2014).
Muscid flies were determined according to Gregor et al.
(2002) and Savage & Wheeler (2004).
During this study five females of N. lundbecki were
collected: three in the semi-natural habitat in June
2009 and two in the rural habitat in June 2010 (Fig.
1).
Information about the biology of Neohydrotaea
is scarce. Bygarski & LeBlanc (2013) reported oc-
currence of Neohydrotaea on pig carcass, where
adult flies were sampled during the bloated stage
of decomposition. Neohydrotaea lundbecki occurs in
forest habitats (Pont et al. 1994). Larvae of N. lund-
becki are likely to be predators, at least as faculta-
tive carnivores in the third instar, since other

Neohydrotaea lundbecki reported from Germany
197
Figure 1. Female of Neohydrotaea lundbecki (Michelsen),
a: habitus; b: head in lateral view; c and d: head in frontal view.
closely related species of Azeliini reveal such be-
haviour (Skidmore 1985) and the species holotype
was reared from larvae collected in decaying
beech wood (Michelsen 1978).
Among factors allowing to recognize species
as a rare, range size, population size and habitat
requirements can be listed (Fontaine et al. 2007).
The former, i.e. limited geographic distribution,
was for several years the case of N. lundbecki. Some
have to ask if the present findings reflect the actual
frequency of N. lundbecki or if they are just high-
lighting one dilemma in taxonomy in general and
especially in biodiversity studies: the presence or
absence of species can be just proven by someone
who is having the skills to identify correctly and is
searching for this particular species. Species rarity
in general, especially in invertebrates, can be just
an artifact arising from the lack of complete spe-
cies inventories and expert taxonomists instead of
actual species frequency. Forensic entomology
studies, due to the mass sampling, are of great
importance for biodiversity studies since they can
reveal taxa considered as rare. However in order
to allow proper species identification of collected
material, researchers should be aware of possible
association of species considered rare and in any
doubtful identifications consult with expert tax-
onomists.
Adults of N. lundbecki can be discriminated
from European Hydrotaea species by the simple,
i.e. not modified, fore femur and tibia as well as
linear parafacials in males and spatulate palpi in
females (Fig. 1c) (Michelsen 1978). Application of
keys intended to identify forensically important
dipterans solely does not lead to N. lundbecki, since
it was not formerly considered a relevant species.
Thus for identification of adult Muscidae associ-
ated with carrion, keys including broad taxon
group are recommended, e.g. Gregor et al. (2002)
for Central Europe. Identification of immature
stages should be done with some reserve, since
such stages e.g. of Neohydrotaea still remain un-
known (Skidmore 1985). Hence it is not valid to
conclude that there were no larvae of N. lundbecki
when researchers in the past did not key it out of
their samples of succession experiments or legal
cases. In the worst case there could be the mis-
identification of N. lundbecki larvae as e.g. Hydro-
taea spp., leading to a misinterpretation of a possi-
ble PMI. Molecular methods support or enable

A. Grzywacz et al.
198
identification of especially the juvenile stages.
Here, DNA barcoding provides a useful option
where so called „universal primers“ are used for
investigating a standard sequence in all organ-
isms. It was shown that the mitochondrial cyto-
chrome c oxidase I (coI) gene is an appropriate
marker to identify forensically important fly spe-
cies (Wells & Stevens 2008). Our project provides a
549 bp fragment of the coI-sequence (GenBank
Acc. No. KP202066) which may serve as reference
data for future identification of N. lundbecki. Com-
bining these modern techniques with traditional
skills in taxonomy is one of the pressing tasks in
forensic entomology. Tools like GenBank can just
be as good as the taxonomists who feed such
search engines by the means of classical methods,
i.e. identifying the specimens based on their mor-
phological characters before sequencing them.
More surveillance studies (see e.g. Fremdt &
Amendt 2014) accompanied by a sound morpho-
logical and molecular identification of the taxa
found will increase the knowledge in forensic en-
tomology and the level of quality in case work.
Acknowledgments. We would like to express our appre-
ciation to Dr. Verner Michelsen (Copenhagen, Denmark)
for confirmation of species identification.
References
Bygarski, K., LeBlanc, H. (2013): Decomposition and Arthropod
succession in Whitehorse, Yukon, territory, Canada. Journal of
Forensic Science 58: 413–418.
Domínguez, M.C., Aballay, F. (2008): A new species of the genus
Fannia Robineau-Desvoidy (Diptera: Fanniidae) collected on pig
carrion in Mendoza, Argentina. Annales Zoologici 58: 819–824.
Fontaine, B., Bouchet, P., Van Achterberg, K., Alonso-Zarazaga, M.
A., Araujo, R., Asche, M., Aspöck, U., Audisio, P., Aukema, B.,
Bailly, N., Balsamo, M., Bank, R. A., Barnard, P., Belfiore, C.,
Bogdanowicz, W., Bongers, T., Boxshall, G., Burckhardt, D.,
Camicas, J. L., Chylarecki, P., Crucitti, P., Deharveng, L., Dubois,
A., Enghoff, H., Faubel, A., Fochetti, R., Gargominy, O., Gibson,
D., Gibson, R., Gómez López, M. S., Goujet, D., Harvey, M. S.,
Heller, K. G., Van Helsdingen, P., Hoch, H., De Jong, H., De
Jong, Y., Karsholt, O., Los, W., Lundqvist, L., Magowski, W.,
Manconi, R., Martens, J., Massard, J. A., Massard-Geimer, G.,
Mcinnes, S. J., Mendes, L. F., Mey, E., Michelsen, V., Minelli, A.,
Nielsen, C., Nieto Nafría, J. M., Van Nieukerken, E. J., Noyes, J.,
Pape, T., Pohl, H., De Prins, W., Ramos, M., Ricci, C., Roselaar,
C., Rota, E., Schmidt-Rhaesa, A., Segers, H., Zur Strassen, R.,
Szeptycki, A., Thibaud. J. M., Thomas, A., Timm, T., Van Tol, J.,
Vervoort, W., Willmann, R. (2007): The European union’s 2010
target: Putting rare species in focus. Biological Conservation 139:
167–185.
Fremdt, H., Amendt, J. (2014): Species composition of forensically
important blowflies (Diptera: Calliphoridae) and fleshflies
(Diptera: Sarcophagidae) through space and time. Forensic
Science International 236: 1–9.
Fremdt, H., Szpila, K., Huijbregts, J., Lindström, A., Zehner, R.,
Amendt, J. (2012): Lucilia silvarum Meigen, 1826 (Diptera:
Calliphoridae) - a new species of interest for forensic
entomology in Europe. Forensic Science International 222: 335–
339.
Gregor, F., Rozkošný, R., Barták, M., Vaňharam J. (2002): The
Muscidae (Diptera) of Central Europe. Brno, Folia Biologia 1–
280.
Grzywacz, A., Prado e Castro, C. (2012): New records of Fannia
Robineau-Desvoidy (Diptera: Fanniidae) collected on pig
carrion in Portugal with additional data on the distribution of F.
conspecta Rudzinski, 2003. Entomologica Fennica 23: 169–176.
Hwang, C., Turner, B.D. (2005): Spatial and temporal variability of
necrophagous Diptera from urban to rural areas. Medical and
Veterinary Entomology 19: 379–391.
Martín-Vega, D., Baz, A., Michelsen, V. (2010): Back from the dead:
Thyreophora cynophila (Panzer, 1798) (Diptera: Piophilidae)
‘globally extinct’ fugitive in Spain. Systematic Entomology 35:
607–613.
Matuszewski, S., Bajerlein, D., Konwerski, S., Szpila, K. (2008): An
initial study of insect succession and carrion decomposition in
various forest habitats of Central Europe. Forensic Science
International 180: 61–69.
Michelsen, V. (1978): Cryptophyra lundbecki n. gen et n. sp. from
North Europe, with some notes on allied hydrotaeine genera
(Diptera: Muscidae). Entomologica scandinavica 9: 85–92.
Pont, A.C. (1986): Family Muscidae. pp. 1–345. In: Soós, A., Papp, L.
(eds.), Catalogue of Palaearctic Diptera. Scatophagidae –
Hypodermatidae. Volume 11. Elsevier: Amsterdam.
Pont, A.C., d’Assis-Fonseca, E.C.M., Ackland, D.M. (1994):
Hydrotaea lundbecki (Michelsen, 1978) (Dipt., Muscidae), new to
Britain. Entomologist Monthly Magazine 130: 247–248.
Prado e Castro, C., Arnaldos, M.I., García, M.D. (2010): Additions
to the Calliphoridae (Diptera) fauna from Portugal, with
description of new records. Boletín de la Asociación Española de
Entomología 33: 425–437.
Savage, J., Wheeler, T. (2004): Phylogeny of the Azeliini (Diptera:
Muscidae). Studia Dipterologica 11: 259–299.
Skidmore, P. (1985): The biology of the Muscidae of the world.
Series Entomologica 29: 1–550.
Smith, K.G.V. (1986): A Manual of Forensic Entomology. London:
British Museum (Natural History), Cornell University Press,
New York.
Szpila, K. (2010): Key for the identification of third instars of
European Blowflies (Diptera: Calliphoridae) of forensic
importance, pp. 43–56. In: Amendt, J., Goff, M.L., Campobasso,
C.P., Grassberger, M. (eds.), Current concepts in forensic
entomology, Springer: Dordrecht.
Wells, J.D., Stevens J.R. (2008): Application of DNA-based methods
in forensic entomology. Annual Review of Entomology 53: 103-
120.