Hirtodrosophila of North America (Diptera: Drosophilidae)

2018·39.2 MB·English

by  David A. Grimaldi

HIRTODROSOPHILA OF NORTH AMERICA
(DIPTERA: DROSOPHILIDAE)
DAVID A. GRIMALDI
Division of Invertebrate Zoology
American Museum of Natural History
BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY
Number 421, 75 pp., 43 figures
Issued June 21, 2018
Copyright © American Museum of Natural History 2018 ISSN 0003-0090
CONTENTS
Abstract.............................................................................3
Introduction.........................................................................3
Historical Context .................................................................3
Methods and Materials................................................................5
Systematics..........................................................................7
Genus Hirtodrosophila Duda ........................................................7
Hirtodrosophila alabamensis (Sturtevant)..........................................21
Hirtodrosophila chagrinensis (Stalker and Spencer) .................................26
Hirtodrosophila cinerea (Patterson and Wheeler) ...................................28
Hirtodrosophila duncani (Sturtevant) .............................................29
Hirtodrosophila florida, new species ..............................................33
Hirtodrosophila grisea (Patterson and Wheeler) ....................................36
Hirtodrosophila jaenikei, new species .............................................40
Hirtodrosophila longala (Patterson and Wheeler) ...................................43
Hirtodrosophila orbospiracula (Patterson and Wheeler)..............................47
Hirtodrosophila ordinaria (Coquillett).............................................49
Hirtodrosophila pictiventris (Duda) ...............................................55
Hirtodrosophila prognatha (Sturtevant)............................................60
Hirtodrosophila thoracis (Williston)...............................................63
Key to Hirtodrosophila Species of America North of Mexico............................67
Acknowledgments...................................................................68
References..........................................................................69
Appendix: Photomicrographs of Type Specimens .......................................71
2
ABSTRACT
Species concepts are morphologically revised and updated for members of the mycophagous genus
Hirtodrosophila Duda that occur in America north of Mexico. Photomicrographs of external features,
illustrations of male and female terminalia, and detailed descriptions are provided for 12 species. One
species, H. cinerea (Patterson and Wheeler) is known only from the original description; its status is
uncertain. Species exclusively from the southwestern United States are H. grisea (Patterson and
Wheeler), H. longala (Patterson and Wheeler), and H. orbospiracula (Patterson and Wheeler). Hirto-
drosophila alabamensis (Sturtevant) and H. duncani (Sturtevant) are widespread throughout the eastern
half of North America; the latter species is morphologically disparate for Hirtodrosophila but provision-
ally retained in the genus. Hirtodrosophila chagrinensis (Stalker and Spencer) is very rare, known only
from two female specimens from the northern United States. Hirtodrosophila ordinaria (Coquillett) is
the most widespread species of the genus in North America, occurring throughout the northern half
of the continent up to Alaska; H. shaitanensis (Sidorenko) from far eastern Russia may be a junior
synonym. A preliminary scheme of relationships in the H. melanderi species group (including H.
ordinaria) is presented. Two species from Florida (H. pictiventris [Duda], H. prognatha [Sturtevant])
and one from Florida plus other Gulf states (H. thoracis [Williston]) are widespread throughout the
Caribbean, Central America, and portions of South America. Hirtodrosophila mendeli (Mourão et al.),
from Brazil, may be a junior synonym of H. prognatha. Two new species are described from southern
Florida: H. florida, n. sp., and H. jaenikei n. sp., the latter in the nigrohalterata species complex. A key
to the North American species is provided.
INTRODUCTION fruit baits. They must be collected directly from
the fungus. Thus, Hirtodrosophila specimens are
Hirtodrosophila is a cosmopolitan genus of 157
usually rare in museum collections and the spe-
species of flies that congregate on fungi, their great-
cies and geographic sampling is poor.
est diversity being tropical. Throughout the world
Hirtodrosophila species in other regions have
the preferred hosts appear to be moist, pliant
been described in excellent morphological detail:
polypores (Polyporaceae: “shelf” or “bracket”
for northern Europe (Bächli et al, 2004), the
fungi), although softer fungi are also used, like
Neotropical Region (Vilela and Bächli, 1990,
gilled Pleurotus (Pleurotaceae: Agaricales), the rub-
2004); and Asia (Okada, 1956; Bächli, 1974), in
bery to gelatinous Auricularia (Auriculariaceae:
particular. My intention with the present work is
Auriculariales), and even stink horns (Phallaceae).
to clarify ambiguities that arise in identifying
The fungus is a breeding site, where larvae burrow
and studying the North American species.
into and ingest the fungal tissue, and the spores and
surface yeasts are a source of adult food as well
Historical Context
(Buxton, 1960; Burla and Bächli, 1968; Lacy, 1982;
Shorrocks and Charlesworth, 1980; 1982). The 10 North American species of Hirtodro-
Species of Hirtodrosophila vary greatly in habi- sophila known until now were described piece-
tus from minute, entirely whitish and light yellow- meal in seven papers, as specimens of rare and
ish, to bulky individuals elaborately patterned extralimital species became available to nine tax-
with brown markings, and species that are almost onomists over a period of some 50 years. Almost
entirely black. Unlike the closely related genera all the species were originally described in the
Mycodrosophila and especially Zygothrica, the genus Drosophila or in Hirtodrosophila after it
wings are rarely patterned. Because they settle on was classified as a subgenus of Drosophila.
their fungus hosts, these flies are not typically cap- The first species identified, H. thoracis (Wil-
tured using standard insect-collecting techniques liston), was originally known only from the
such as sweeping, Malaise traps, or trapping with Caribbean island of St. Vincent, described by
3
4 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 421
Samuel W. Williston (1852–1918) in his mono- One group involved Harrison D. Stalker
graph of the flies of that island (Williston, 1896). (1915–1982) and Warren P. Spencer (1898–
Williston was a physician, paleontologist, ento- 1969). Like Sturtevant, Stalker was principally
mologist, and noted professor, and is often con- a geneticist but also an extraordinarily broad
sidered the first American-born dipterist. His biologist and naturalist. The main contribu-
Diptera of St. Vincent (1896) is one of the first tion by Spencer, who was a professor at the
major studies of a Neotropical fly fauna. College of Wooster in Ohio, was in taxonomy.
Daniel W. Coquillett (1856–1911) described In a 1939 letter to Sturtevant, he lamented, “I
the second species in the genus, H. ordinaria hope that you and Dobzhansky and Patterson
(Coquillett) from throughout the northern half and his crowd leave a few odd sub-species or
of North America (Coquillett, 1904). He was an species still to be collected by the time I get
applied entomologist and taxonomist working time and money to take a crack at it...” (Kohler,
for the USDA and, as “honorary custodian” of 1994: 140). Spencer actually did have the
the USNM collection at that time, he described opportunity to codescribe an “odd” species
over 1,000 species of flies in 67 families. that very same year, Hirtodrosophila chagrinen-
One of the most influential early workers on sis (Stalker and Spencer), still one of the rarest
drosophilids was Alfred H. Sturtevant (1891– species of drosophilids in North America,
1970), who described Hirtodrosophila alabam- which I redescribe in the present paper. He
ensis, H. duncani, H. melanderi (a synonym of probably was not fully aware in 1939 of how
H. ordinaria [Lacy, 1981]), and H. prognatha Patterson’s group was just getting started.
(known only from the Caribbean at the time) Sturtevant also assisted and advised in its ear-
(Sturtevant, 1916, 1918a, 1918b). He published lier days the University of Texas (UT) Drosophila
these and other descriptions while still a gradu- group, then led by John T. Patterson. The UT
ate student in the famed “Fly Group” of T.H. group conducted an enormous amount of col-
Morgan at Columbia University, soon thereafter lecting, descriptions, karyotyping, mating tests
monographing the North American fauna and other studies on drosophilids from approxi-
(Sturtevant, 1921). mately 1938 to 1970, particularly on species from
Contemporaneous with Sturtevant and southwestern North America, including Mexico
equally influential was the German physician (e.g., Patterson, 1943; Patterson and Stone, 1952),
and amateur dipterist, Oswald Duda, who and later in the Neotropics. One of the first
described H. nigrohalterata and H. pictiventris, major taxonomic articles from the group was
from Costa Rica (Duda, 1925), the latter spe- Patterson and Wheeler (1942), in which 37
cies now known to be very widespread. Duda’s North American species of Drosophila and Hirto-
work was careful for its time; he published drosophila were described, among them H. cine-
detailed descriptions along with drawings of rea (Patterson and Wheeler), H. grisea (Patterson
external terminalia and other microscopic and Wheeler), H. longala (Patterson and
characters, and even photomicrographs of Wheeler), and H. orbospiracula (Patterson and
wings (e.g., Duda, 1925). His taxonomic focus Wheeler). Scientific legacies of the UT Drosoph-
was on acalyptrates, especially Chloropidae ila group were many, including a collection of
and Drosophilidae; he monographed droso- living cultures with hundreds of species, which
philids from Africa, Costa Rica, Indonesia, eventually became the Drosophila Species Center
and Taiwan, working principally with collec- that over the years has relocated to five U.S. uni-
tions from Berlin and Budapest. versities. Another major legacy of the group
Sturtevant continued working on the sys- involved the graduate students who continued
tematics of drosophilids into the 1950s, mostly with the research program as faculty at various
assisting new groups of American workers. universities. The most influential of all the stu-
2018 GRIMALDI: NORTH AMERICAN HIRTODROSOPHILA 5
dents was Marshall R. Wheeler (1917–2010), of male genitalia from descriptions has greatly
who coauthored the description of four of the complicated identification of the richest
North American Hirtodrosophila species. He archives of specimens, which reside in
continued at UT as a professor, as steward to the museums.
large collections of living cultures and preserved The only recent work on North American
specimens, and as a world authority on droso- Hirtodrosophila is that of Lacy (1981), who rede-
philid systematics. scribed H. ordinaria, provided the first figures of
Despite the history of drosophilid research male genitalia, and formally established that H.
in the United States, the North American spe- melanderi and H. magnafumosa are junior syn-
cies of Hirtodrosophila have been poorly char- onyms of H. ordinaria. Lacy (1982) provided data
acterized and difficult to identify. This is on allozyme variation and host use for two eastern
partly due to the obscurity of Hirtodrosophila. species, H. ordinaria and H. duncani, among other
By 1942, when all but two of the species were species of mycophagous drosophilids.
described, the total number of specimens I am providing for the first time images of the
reported in the literature for Hirtodrosophila external morphology, along with descriptions
was 35. Sampling has improved since then, but and illustrations of the genitalia for both sexes of
not by much. Three species, for example, are most North American species. I am also adding
still known from only one or two specimens: some new geographical and host records, and
H. chagrinensis, H. jaenikei, n. sp., and H. can confirm that the widespread Neotropical
orbospiracula. There are no specimens known species H. pictiventris and H. thoracis occur in
for Hirtodrosophila cinerea. the United States (as mentioned in the catalog by
The other reason for the poor species char- Wheeler [1981]), based on my comparison of
acterization is of course the nature of insect male genitalia to those of specimens throughout
systematics in the time of Williston, Coquil- their neotropical ranges. What had been thought,
lett, Sturtevant, and Duda. Ironic, though, is however, to be H. nigrohalterata in Florida (e.g.,
the meticulous effort by the UT Drosophila Wheeler, 1981) is actually a new species,
group in dissecting and illustrating the soft, described here. A striking new species, also from
internal reproductive organs like testes and Florida, is presented.
ovaries and the karyotyping of a great many
species, without illustrating the male genitalia.
METHODS AND MATERIALS
By the 1950s it was well known that the com-
plex sclerotized structures of male genitalia, The specimens used for this study derive from
such as the surstyli, hypandrium, and aedeagus, my own fieldwork and that of several others (see
and even the female terminalia (e.g., oviscapt, Acknowledgments), along with the examination
spermathecae) are most informative for mor- of type and nontype museum specimens. Unless
phologically separating and identifying species specified the specimens are in the AMNH. Pres-
(e.g., Okada, 1956). In fact, Wheeler made ervation techniques varied from air-drying for
thousands of permanent slide mounts of the the older specimens (which leaves them slightly
genitalia of many species (housed in the greasy, faded, and collapsed, making the inter-
AMNH), well before he began to illustrate pretation of original colors difficult) to critical-
these structures in his publications in the point drying (CPD) and drying with the solvent
1960s. The early UT practice may have been HMDS (hexamethyldisilazane) for more recent
based on a perception that the soft internal ones (which leaves them fully distended, clean,
reproductive organs and chromosomes should with natural colors well preserved). A drawback
be particularly informative in a phylogenetic with HMDS-dried specimens is that the DNA is
sense. Regardless of the reason, the omission probably not preserved. I have tried to base
6 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 421
FIG. 1. Polyporus fungus host of Drosophila duncani, in New Jersey. Ten specimens were found amongst an
aggregation of several hundred specimens of Mycodrosophila claytonae Takada and Wheeler (in center).
descriptions and photomicrographs on well-pre- made of 85 specimens; applied to the pin for each
served specimens, though only old, historical is a label with a sequential number, prefixed by
specimens were available for some species. NAHD (“North American Hirtodrosophila”). For
Dissections involved snipping off certain body photomicrographs and illustrations I used North
parts and macerating in very warm (not boiling) American specimens, unless otherwise indicated.
10% KOH for about two hours, then rinsing in Measurements were made on dried, point-
water, then 70% ethanol, and disarticulating with mounted specimens (and for some wings, slide
fine minutens in glycerin, and then mounting on mounted) using Nikon NIS Elements® software
glass slides using glycerin jelly (gelatin). Sketches on an SMZ 1500 stereoscope. Measurements
involved use of a drawing tube on a compound were standard ones used for drosophilids, the
microscope. Afterward, each dissection was protocols described in Bächli et al. (2004) and
placed in a small drop of glycerine and stored in summarized as follows:
small capsules pinned below the specimen. Even Head: CD, cheek depth; CD/ED ratio; ED,
if kept moist, over years glycerin jelly will become greatest length of eye; ED/EW ratio; EW, greatest
impossible to melt. Dissections in old glycerin width of eye; FD, face depth below uppermost
jelly are easily removed by soaking in a small well margin of ptilinal suture; FD/FW ratio; FL, frontal
of very warm lactic acid, which will dissolve the (frons) length; FW, face width, between lateral
old matrix in about an hour. For this project dis- margins of ptilinal suture; HD, head depth, from
sections of terminalia (male and female) were ocellar mound to bottom of cheek; HW, head
2018 GRIMALDI: NORTH AMERICAN HIRTODROSOPHILA 7
width (between outside margins of eyes); HW/ SYSTEMATICS
HD ratio; IV, length of inner vertical seta; LFW,
Genus Hirtodrosophila Duda
width of frons above ptilinum; OC, length of ocel-
lar seta; Ocellar S-index, OC/POC; OR1, length of Hirtodrosophila Duda 1923: 41. As subgenus,
proclinate orbital seta; OR1/OR3 ratio; OR2, type species Drosophila carinata Duda;
length of anterior reclinate orbital seta; OR2/OR1 Grimaldi (1990), elevated to genus.
ratio; OR3, length of posterior reclinate orbital Dasydrosophila Duda, 1925: unjustified replace-
seta; OV, length of outer vertical seta; POC, length ment for Hirtodrosophila.
of postocellar seta; VT-index, IV/OV.
Diagnosis: Eye from bare to having short,
Thorax and Wing: 4-V index, MIV/MIII;
dense pilosity; anterior reclinate orbital seta
5X-index, ratio of CuAA/dm-cu; ADC, anterior
small to minute; postocellar setae generally
dorsocentral seta length; AKE, anterior katepi-
crossing; carina generally very short and nar-
sternal seta (“sternopleural”) length; CII, costal
row, nearly missing in some species; arista
length between tip of R (or costal break) and tip
1
almost always with one ventral branch, near
of R ; CIII, costal length between tip of R
2+3 2+3
apex; basal flagellomere with long fine setulae
and R ; CIIIb, length of thick spinules along
4+5
in some species; cibarium with sclerotized
CIII section; CuAA, length of CuA distal to
hypopharyngeal bulb, reduced number of
crossvein dm-cu; DC-index, ADC/PDC; dm-cu,
medial sensilla (Grimaldi, 1990); oviscapt with
length of this crossvein; MIII, length along M
simple margin or apical pegs differentiated,
between crossveins; MIV, length along M distal
spermathecal capsule generally rounded, sclero-
to dm-cu crossvein; PDC, posterior dorsocentral
tized; male: cerci not connected to epandrium;
seta length; PKE, posterior katepisternal seta
epandrium often with well-developed ventral
(“sternopleural”) length; S-index, AKE/PKE;
lobe; surstylus often divided into dorsal and
ThL, thorax length; ThL/WL ratio; WL, wing
ventral lobes; hypandrium and aedeagus well
length; WL/WW ratio; WW, wing width.
developed but relatively simple.
The descriptions include just the ratios/indi-
Type Species: Hirtodrosophila carinata Duda.
ces, with the exception of thorax length (ThL),
Comments: The genus is probably paraphy-
used here as an index of body size. The number
letic with respect to Mycodrosophila Oldenberg,
after each ratio/index is the average, followed by
Paramycodrosophila Duda, and Zygothrica Wie-
the range in parentheses; if there is just one
demann. Each of these particular genera
number then there was either just one specimen
appears to be monophyletic (Grimaldi, 1987;
measured or the value was invariant.
1990), but may be closely related to certain
For many of the distribution records mapped
groups within Hirtodrosophila. There are some
out for each species by Patterson (1943), speci-
groups within Hirtodrosophila that appear to be
mens were not retained in the former UT col-
monophyletic, such as the H. hirticornis group
lection, making it difficult to impossible to
(defined by the large, projecting pegs at the
assess their identifications. I cite such records
apex of the oviscapt). If this is the case, there
below in the comments section of the respective
may need to be a division of some Hirtodro-
species. Those specimens that were retained
sophila into these other genera, with a more
were usually just representative slide-mounted
narrowly defined Hirtodrosophila (sensu stricto)
dissections, which bear numbers corresponding
for some. Any reclassification should ideally
to entries in field notebooks with full data. I
involve a revision of the world species as well as
have quoted field notes verbatim where I felt it
further phylogenetic study using morphological
was necessary; otherwise, this information was
and molecular data.
condensed here.
8 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 421
FIG. 2. Hirtodrosophila alabamensis. A. Head, frontal (male). B. Thorax, dorsal (male). C. Head and thorax,
lateral (male). D. Abdomen, dorsal (female).
2018 GRIMALDI: NORTH AMERICAN HIRTODROSOPHILA 9
FIG. 3. Hirtodrosophila chagrinensis (female) A. Habitus, lateral. B. Head, frontal. C. Abdomen, dorsal.