Biodiversity Data Journal : Single Taxon Treatment
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Single Taxon Treatment
A new white-spotted Megaselia Rondani (Diptera: Phoridae) from western North America
expand article infoBrian V. Brown, Maria A. Wong, Emily Hartop§,|,¶,
‡ Natural History Museum of Los Angeles County, Los Angeles, California, United States of America
§ Naturhistoriska Riksmuseet, Stockholm, Sweden
| Stockholms Universitet, Stockholm, Sweden
¶ Station Linné, Färjestaden, Sweden
Open Access

Abstract

Background

The phorid fly genus Megaselia Rondani is a large, poorly-known taxon whose species are found worldwide.

New information

A new species of Megaselia Rondani, M. simunorum, is described from both urban and rural sites in southern California. With a large area of white colour on the posterior part of the abdominal dorsum, it closely resembles the much more common species M. sulphurizona, but M. simunorum has distinctly thicker ventral setae on the abdomen and a differently-shaped white spot.

Keywords

Diptera, Phoridae, Megaselia, new species, urban biodiversity

Introduction

The enormous genus Megaselia Rondani has many difficult-to-separate species, but a few seem almost immediately identifiable, such as the common western North American species Megaselia sulphurizona Borgmeier. This species, although originally described from just eight specimens from California, Washington and Idaho, USA, is widespread within western USA and is one of the most abundant species collected in urban Los Angeles by the BioSCAN project (Brown and Hartop 2016). The original description (Borgmeier 1966) noted that tergites 5 and 6 of the male were wholly or partly “pale yellow”, a character upon which the name was based (translation of sulphurizona is loosely “yellow belt”). Borgmeier was working with air-dried specimens, in which colour can be distorted, however and we found that fresh specimens usually have a white spot. Regardless, until now, the identification of M. sulphurizona has been extremely straightforward.

Amongst the many thousands of phorid flies captured by Malaise traps in the BioSCAN project were a few specimens of “another” white-spotted species. Furthermore, we found large differences in the extent of the white colour on the dorsum of M. sulphurizona and started to explore the variation within this species. We take this opportunity to describe our first, most distinctive, new white-spotted Megaselia that, based on its divergent abdominal structure, is apparently not closely related to M. sulphurizona (whose systematics we plan to study later).

Materials and methods

The description of this species follows the reduced, table-based method we previously established (Hartop and Brown 2014,Hartop et al. 2015, Hartop et al. 2016). Specimens were collected in Townes lightweight Malaise traps (Townes 1972) and preserved in 95% alcohol. Some specimens were dried using HMDS (Brown 1993) and glued to insect pins; others were slide-mounted following Disney (2009), except that the permanent mounting medium Canada Balsam was used. Most specimens are stored in the Natural History Museum of Los Angeles County (LACM), although some were placed in the collections of the California Academy of Sciences (CAS) and the California Department of Food and Agriculture (CSCA).

Taxon treatment

Megaselia simunorum Brown, Wong, and Hartop, sp. n.

Materials    Download as CSV 
Holotype:
  1. country:
    USA
    ; stateProvince:
    California
    ; county:
    Los Angeles
    ; locality:
    Encino
    ; verbatimCoordinates:
    34.167°N, 118.513°W
    ; verbatimCoordinateSystem:
    decimal degrees
    ; decimalLatitude:
    34.167
    ; decimalLongitude:
    -118.513
    ; eventID:
    BioSCAN 18490
    ; samplingProtocol:
    Malaise trap
    ; sex:
    male
    ; catalogNumber:
    LACM ENT 366270
    ; institutionCode:
    LACM
    ; basisOfRecord:
    Preserved specimen
Paratypes:
  1. country:
    USA
    ; stateProvince:
    California
    ; county:
    Kern
    ; locality:
    Wind Wolves Preserve
    ; verbatimCoordinates:
    34.956°N, 119.187°W
    ; verbatimCoordinateSystem:
    decimal degrees
    ; decimalLatitude:
    34.956
    ; decimalLongitude:
    -119.187
    ; samplingProtocol:
    Malaise trap
    ; verbatimEventDate:
    9-15.v.2018
    ; sex:
    male
    ; lifeStage:
    adult
    ; recordedBy:
    B.Brown, G.Kung
    ; institutionID:
    LACM
    ; institutionCode:
    LACM
    ; basisOfRecord:
    PreservedSpecimen
  2. country:
    USA
    ; stateProvince:
    California
    ; county:
    Los Angeles
    ; verbatimLocality:
    Topanga Canyon
    ; verbatimElevation:
    250 m
    ; minimumElevationInMeters:
    250
    ; maximumElevationInMeters:
    250
    ; decimalLatitude:
    34.08
    ; decimalLongitude:
    -118.60
    ; samplingProtocol:
    Malaise trap
    ; verbatimEventDate:
    7-14.iii.1994
    ; sex:
    male
    ; recordedBy:
    B.Brown, G.Hendler
    ; institutionID:
    LACM
    ; basisOfRecord:
    PreservedSpecimen
  3. country:
    USA
    ; stateProvince:
    California
    ; county:
    San Luis Obispo
    ; locality:
    Los Osos,Pecho Willows
    ; verbatimLocality:
    Pecho Willows
    ; verbatimElevation:
    5 m
    ; decimalLatitude:
    35.317
    ; decimalLongitude:
    -120.853
    ; samplingProtocol:
    Malaise trap
    ; verbatimEventDate:
    2-8.vii.2017
    ; eventRemarks:
    old field near bay
    ; individualCount:
    3
    ; sex:
    male
    ; lifeStage:
    adult
    ; recordedBy:
    B.V.Brown
    ; institutionID:
    LACM
    ; basisOfRecord:
    PreservedSpecimen
  4. country:
    USA
    ; stateProvince:
    California
    ; county:
    San Luis Obispo
    ; locality:
    Rancho El Chorro
    ; verbatimElevation:
    110 m
    ; decimalLatitude:
    35.34
    ; decimalLongitude:
    -120.73
    ; samplingProtocol:
    Malaise trap
    ; verbatimEventDate:
    5-8.vii.2017
    ; habitat:
    forest near stream
    ; individualCount:
    3
    ; sex:
    male
    ; lifeStage:
    adult
    ; recordedBy:
    B.V.Brown
    ; collectionID:
    LACM
    ; basisOfRecord:
    Preserved specimen
  5. country:
    USA
    ; stateProvince:
    California
    ; county:
    San Mateo
    ; locality:
    Palo Alto, Stanford University
    ; samplingProtocol:
    Malaise trap
    ; verbatimEventDate:
    1-15.i.1995
    ; individualCount:
    7
    ; sex:
    male
    ; lifeStage:
    adult
    ; recordedBy:
    P.H.Arnaud
    ; institutionID:
    CAS, CSCA, LACM
    ; basisOfRecord:
    PreservedSpecimen
  6. country:
    USA
    ; stateProvince:
    California
    ; county:
    San Mateo
    ; locality:
    Palo Alto, Stanford University
    ; samplingProtocol:
    Malaise trap
    ; verbatimEventDate:
    26-31.xii.1994
    ; individualCount:
    3
    ; sex:
    male
    ; lifeStage:
    adult
    ; recordedBy:
    P.H.Arnaud
    ; institutionID:
    LACM
    ; basisOfRecord:
    PreservedSpecimen

Description

See Table 1. A CO1 barcode is deposited in the BOLD database as BOLD: ADK7956.

Description of Megaselia simunorum new species (Figs 1, 2, 3, 5)

Head

SA ratio

0.42-0.68

VIF position

normal

SPS vesicles

present

Palpal setae length

long

Labellum spinosity

spinose

Thorax

Anepisternum

bare

Relative halter colour

lighter

# NP setae

2

NP cleft

absent

Scutellar setae

2+2

Leg

ts1 palisade

1 to 4

t2 palisade

0.65-0.75

t3 comb bifurcate

absent

t3 setulae

PD only

f3 basal setae

B<AV

f3 basal setae differentiation

absent

Wing

Fig. 5

Wing Length (mm)

1.49-1.88

Subcosta

complete (but apically faint)

R seta

long

R2+3

present

Costal index

0.36-0.45

Costal ratios

2.83-3.77: 1.44-2.08: 1

Costal setae length (mm)

0.10-0.14

Number alular setae

3

Alular setae length (mm)

0.09-0.14

Wing colour

lightly infuscated/ clear

Genitalia

Fig. 3

AT length

AT<E

E setation

hairs + bristles

General Remarks

Membranous, semi-circular white spot on tergites 5 and 6; abdominal venter with conspicuous plumose setae coming out of sclerotised sockets.

Diagnosis

This species differs from all North American Megaselia, except those similar to M. sulphurizona, by the contrasting white colour of the posterior abdominal tergites. The lighter coloured halter, stronger ventral abdominal setae (compare with M. sulphuriza, Fig. 4) and the reduced tergite 5 with large posterior setae further distinguish this species.

Figure 1.  

Megaselia sinumorum new species, male, lateral.

Figure 2.  

Megaselia simunorum new species, male abdomen, dorsal.

Figure 3.  

Megaselia simunorum new species, male, abdomen lateral.

Figure 4.  

Megaselia sulphurizona Borgmeier, male abdomen, lateral.

Figure 5.  

Megaselia simunorum new species, wing

Etymology

Named in memory of Dr. Patricia Bates Simun and Mr. Richard V. Simun by their daughters, Ann and Mary.

Distribution

Known only from California, USA (Fig. 6).

Figure 6.  

Distribution of M. simunorum new species in California.

Ecology

The habitats at the sites where this species was collected vary from a willow spring in an interior grassland (Wind Wolves), a sycamore/oak forest near a small creek, a coastal floodplain, an old field near the coast, to an inland urban backyard. Many involve at least some exposed water, but this might be simply a reflection of where we put our Malaise traps.

Acknowledgements

We thank the site hosts of the BioSCAN project for making this research possible, in this case, Laura Schare. The BioSCAN project was also supported by Ester Chao, the Seaver Foundation and Luis Chiappe (in his role as Senior VP of Research & Collections at the LACM). We also thank Celeste Royer of Rancho El Chorro and Landon Peppel of Wind Wolves Preserve for permission to collect. For technical support, we thank Estella Hernandez and Giar-Ann Kung of the LACM and Daisy Carrillo, Charissa Fisher, Elizabeth Perez and Brooke Wainwright of Wind Wolves Preserve.

References