A New Species of Drosophila associated to X. sagittifolium

Llangarí and Rafael

p-ISSN 2477-9113

e-ISSN 2477-9148

REVISTA ECUATORIANA DE MEDICINA Y CIENCIAS BIOLOGICAS

Volumen 38. No. 1, Mayo 2017

A New Species of Drosophila (Diptera: Drosophilidae) from the Inorescences

of Xanthosoma sagittifolium (Araceae)

Luz Marina Llangarí

* y Violeta Rafael

Laboratorio de Genética Evolutiva, Escuela de Ciencias Biológicas, Ponticia Universidad Católica del Ecuador,

Apartado: 17-01-2184, Quito, Ecuador.

*luzmarinallangari@gmail.com

doi:10.26807/remcb.v38i1.21

Recibido 10-02-2017; Aceptado 23-03-2017

ABSTRACT.- A new species of the genus Drosophila, Drosophila sagittifolii sp. nov. is described. Adult specimens

of D. sagittifolii were aspirated from the inorescences of Xanthosoma sagittifolium (L.) Schott (camacho), from

which they also emerged, at the Río Guajalito Research Station, Santo Domingo de los Tsáchilas, Ecuador.

KEYWORDS: biology, breeding site, Ecuador, feeding site, taxonomy

RESUMEN.- Una nueva especie del género Drosophila, Drosophila sagittifolii sp. nov. es descrita. Los adultos de

D. sagittifolii fueron aspirados de las inorescencias de Xanthosoma sagittifolium (L.) Schott (camacho) del cual

también emergieron, en la Reserva Ecológica Río Guajalito, Santo Domingo de los Tsáchilas, Ecuador.

PALABRAS CLAVES: biología, Ecuador, sustrato imago, sustrato larval, taxonomía.

INTRODUCTION

In Ecuador, most collections of Drosophila use

fruit-baited traps to study fruit ies, and for

this reason little is known about the ecology of

ower-breeding and feeding Drosophila species.

However, some Ecuadorian species from the fo-

llowings species groups: Drosophila avopilosa

Frey, 1919, Drosophila bromeliae Sturtevant, 1921,

Drosophila onychophora Vilela & Bächli, 1990

and Drosophila morelia Vilela, 2004 have been

found living in owers of the botanical families

Solanaceae, Bromeliaceae and Asteraceae (Silva

and Martins 2004, Vilela and Bachli 2004, Figuero

and Rafael 2011, Figuero et al. 2012, Robe et al.

2014).

In particular, interactions like reproductive eco-

logy between species of Araceae and ies have

been observed (Gibernau 2003, Miyake and

Yafuso 2005). Specically, species of the genus

Colocasiomyia (Diptera:Drosophilidae) are found

on inorescences of the Araceae genus, Aloca-

sia, Colocasia and Homalonema (Miyake and

Yafuso 2005). Furthermore, Tsacas and Chassag-

nard (1992) suggests the existence of a close as-

sociation between Xanthosoma robustum of the

Araceae family and Drosophila aracea. The afore-

mentioned relationship is likely to occur in Ecua-

dorian areas where low altitude and high humidity

produce a high species richness of Araceae (Leim-

beck et al. 2004). Xanthosoma, an abundant Ara-

ceae terrestrial herb, is a genus whose inorescen-

ces provide shelter to communities of arthropods

(García-Robledo et al. 2004). Moreover, the plants of

Xanthosoma sagittifolium are commonly cultiva-

ted in the American tropics because their tubers are

used as food (Missouri Botanical Garden 2017). Its

inorescence is made up of a spadix and a sphate:

the spadix has pistillate owers at the base, steri-

le owers in the middle, and staminate owers in

the upper part (García-Robledo et al. 2004, Taka-

no et al. 2012). This paper describes a new species

of Drosophila associated with the inorescence of

Xanthosoma sagittifolium (L.) Schott (camacho)

(Araceae).

Artículo científico

REMCB 38 (1): 55-62, 2017

MATERIALS AND METHODS

The collections of drosophilids were carried out

in the Río Guajalito Research Station, Santo Do-

mingo de los Tsáchilas, Ecuador, (00°13´48´´S;

78°49´16´´W), from 1 800 to 2 200m above sea level.

Collections were made during six nonconsecu-

tive months (September 2010, March, June, July,

August and September 2011). Adult specimens of

Drosophila were collected directly from the in-

orescences of Anthurium spp. and Xanthoso-

ma sagittifolium (Figure 1) using an entomo-

logical aspirator. Several inorescences were

also collected with the possibility that they

contained eggs and larvae. These inorescen-

ces were kept in the laboratory in glass jars with

moist paper until emergence of the imagines.

The external morphology of each y was exami-

ned under a stereomicroscope (Zeiss; Discovery

V8) and measured with the AxioVision program.

The terminalia were dissected from the abdomen for

description and preserved in 60% glycerol solution in

microvials stored with the pinned specimens meaans

of morphological characters and indices are presen-

ted with ranges in parentheses. Descriptive terms

and indices are as described as Bächli et al. (2004).

The types and paratypes of the new species

have been deposited in the Museo de Zoo-

logía-Invertebrados, Ponticia Universi-

dad Católica del Ecuador, Quito (QCAZ).

Drosophila Fallén, 1823

Drosophila sagittifolii sp. nov.

(Figures 2–10)

Type material. Male Holotype (dissected, termina-

lia in microvial), labelled “D. sagittifolii Holotype

♂ Llangarí & Rafael det. 2013 Ex. X. sagittifolium/

Ecuador, Santo Domingo de los Tsáchilas, Esta-

ción Cientíca Río Guajalito 1 800m; 00°13´48´´S

78°49´16´´W; VI. 2011; Col. L.M. Llangarí;

(QCAZ 2757); ten males paratypes labelled “D.

sagittifolii Paratype ♂ Llangarí & Rafael det. 2013

Ex. X. sagittifolium/ Ecuador, Santo Domingo de

los Tsáchilas, Estación Cientíca Río Guajalito 1

800m; 00°13´48´´S 78°49´16´´W; VI. 2011; Col.

L.M. Llangarí; (QCAZ 2748, 2749, 2750, 2751,

2752, 2753, 2754, 2755, 2756, 2769). Female alo-

type (dissected, terminalia in microvial), labelled

“D. sagittifolii alotype ♀ Llangarí & Rafael det.

2013 Ex. X. sagittifolium/ Ecuador, Santo Domingo

de los Tsáchilas, Estación Cientíca Río Guajali-

to 1 800m; 00°13´48´´S 78°49´16´´W; VI. 2011;

Col. L.M. Llangarí; (QCAZ 2767)” ten female pa-

ratypes “D. sagittifolii Paratype ♀ Llangarí & Ra-

fael det. 2013 Ex. X. sagittifolium/ Ecuador, Santo

Domingo de los Tsáchilas, Estación Cientíca Río

Guajalito 1800 m; 00°13´48´´S 78°49´16´´W; VI.

2011; Col. L.M. Llangarí; (QCAZ 2758, 2759,

2760, 2761, 2762, 2763, 2764, 2765, 2766, 2768).

Diagnosis.- Arista generally with 2 dorsal and 2

ventral branches, plus terminal fork. Basal scu-

tellars setae are convergent. Median katepister-

nal seta is tiny. Wings with the anterior crossvein

and the posterior crossvein slightly shadowed.

Surstylus with 10 (10–12) prensisetae and ca.

14 inner and 3 outer setae. The triangular dis-

tal tip of the aedeagus is membranous. The su-

bapical part presents lateral claw-shaped chitini-

zed extensions. Hypandrium hourglass-shaped.

Description.- Male. Head. Frons yellowish-brown,

frontal length 0.33 (0.30-0.34) mm; frontal index =

0.78 (0.70–0.83), top to bottom width ratio = 1.32

(1.24-1.34). Frontal triangle brown. Ocellar trian-

gle blackish-brown about 43% (40–45) % of frontal

length. Orbital setae black, distance of or3 to or1,

107% (101–117) % of or3 to vtm, or1/or3 ratio

0.93 (0.90–1.20), or2/or1 ratio 0.62 (0.46–0.71),

postocellar setae 53% (47–59) % and ocellar setae

88% (77–91) % of frontal length; vt index = 0.96

(0.87–0.98), vibrissal index = 0.52 (0.4–0.61). Face

yellowish-brown. Carina yellow, prominent and sli-

ghtly sulcate. Cheek index = 6.72 (6.44–6.83). Eye

red; eye index = 1.38 (1.12–1.51). Antenna yellow,

arista with 2 dorsal and 2 ventral branches, plus

terminal fork. Proboscis yellow; palpus yellow.

Thorax.- Brown; length 1.40 (1.30–1.60)mm,

7–8 irregular rows of acrostically setulae. h in-

dex = 0.76 (0.70–0.82). Tranverse distance of

dorsocentral setae 2.17 (1.78–2.37) of longi-

tudinal distance, dc index = 0.53 (0.51–0.64).

Scutellum yellowish-brown. Distance between

apical scutellars setae 70 % (67–75) % of that be-

tween apical and basal setae; basal scutellar setae

convergent; scut index = 0.78 (0.77–0.80). Pleura

yellow, sterno index = 0.61 (0.56–0.66), median ka-

tepisternal seta tiny. Halteres yellow. Legs yellow.

Wing with anterior crossvein and posterior crossvei-

neins slightly shadowed. Costal lappet shadowed,

length 2.80 (2.02–2.90)mm, length to width ratio

= 2.20 (2.17–2.30). Indexes: C, 2.45 (2.30–2.60);

ac, 2.80 (1.62–3.00); hb, 0.50 (0.48-0.56); 4C, 0.98

(0.92–1.04); 4v, 1.65 (1.4–1.70); 5x, 1.14 (1.09–

1.20); M, 0.43 (0.40–0.49); prox. x, 0.69 (0.60–0.78).

A New Species of Drosophila associated to X. sagittifolium

Llangarí and Rafael

Abdomen.- (Figure 2) yellow; tergite 1 yellow;

tergite 2 with dorsal midline and triangular-sha-

ped, dark pigmented area that reaches the anterior

edge, a dark line along the trailing edge; tergite 3

with hourglass-shaped dark pigmentation, a dark

line along the trailing edge (in some specimens

less pigmented); tergite 4 yellow, with faint and

diffuse pigmentation near anterior edge and a dark

line along the posterior edge; tergites 5–6 yellow.

Length (body + wings) 4.00 (3.90–4.15)mm

Male Terminalia.- (Figures 4–8). Epandrium (Fi-

gure 4) dorsodistally microtrichose, with ca. 10

lower and ca. 13 upper setae. Cerci (Figure 4) an-

teriorly linked to epandrium, microtrichose and

with many setae. Surstylus (Figure 4) almost rec-

tangular and microtrichose; left and right surstylus

with a row of ca. 10 (10–12) peg-like prensise-

tae, c.a. 13 inner and 7 outer setae. Hypandrium

(Figure 5) hourglass-shaped, longer than epan-

drium. Dorsal arch absent. Gonopod oval, membra-

nous and with one seta medially, near outer margin.

Aedeagus is sclerotized, at the center striated and

less sclerotized. Triangular distal tip is membra-

nous. The subapical part presents lateral claw-sha-

ped chitinized extensions. In ventral view, the

subapical margins have undulations. Apode-

me is wide and sclerotized. Ventral rod is short.

Paraphyses elongated and oval (Figures 6–8).

Female.- General morphology similar to males. Me-

asurements: Frontal length 0.41 (0.39–0.45) mm;

frontal index = 0.96 (0.85–1.03), top to bottom wid-

th ratio = 1.55 (1.49–1.93). Frontal triangle brown.

Ocellar triangle about 30% (28–37) % of frontal

length. Distance of or3 to or1, 1.2 (0.96–1.25)

distance of or3 to vtm, or1/or3 ratio = 0.86 (0.81–

0.95), or2/or1 ratio = 0.47 (0.40–0.56), postocellar

setae 39% (34–43)% and ocellar setae 57% (49–

66)% of frontal length; vt index = 0.88 (0.80–0.93).

Vibrissal index = 0.73 (0.68–0.78). Cheek index =

11.61 (9.33–12.4). Eye index =1.05 (0.98–1.19).

Thorax.- Length 1.1 (0.95–1.42)mm. h index = 0.80

(0.75–0.93). Transverse distance of dorsocentral se-

tae 2.53 (2.00–2.71), longitudinal distance, dc index

= 0.79 (0.65–0.83). Distance between apical scutellar

setae 64% (64–93) % of that between apical and ba-

sal setae; scut index = 0.87 (0.83–0.96). Sterno index

= 0.91 (0.88–0.96), tiny median katepisternal setae.

Figures 1-3. 1) X. sagitifolium (Araceae). Drosophila sagittifolii sp. nov. 2) Male Abdomen; 3) Female Abdomen. Scale

bar 0.5 mm.

REMCB 38 (1): 55-62, 2017

Wing.- Length 3.20 (3.00–3.68) mm, leng-

th to width ratio = 2.58 (2.54–2.63); indexes:

C = 2.60 (2.36–2.82); ac = 2.7 (2.68–2.86);

hb = 0.47 (0.4–0.54); 4C = 1.04 (0.97–1.06);

4v=1.70 (1.40–1.76); 5x=1.20 (1.17–1.45);

M=0.40 (0.38–0.43) y prox. x=0.70 (0.65–0.73).

Abdomen.- (Figure 3) Yellow; tergite 1 yellow,

tergite 2 with dorsal midline and triangular dark

pigmentation; tergite 3 without dorsal midline, with

hourglass-shape pigmentation that extends laterally

to the margin; tergite 4 without dorsal midline, with

a tenuous stripe near the edge and a dark stripe on the

posterior edge; tergite 5 yellow with a dark line along

the posterior edge; tergite 6 yellow (in some females,

area around the abdomen may be slightly darker).

Length (Body + wings) 4.3 (4.1–4.50) mm

Female Terminalia.- (Figures 9–10). Valve of

oviscapt (Figure 9) sclerotized, oval, apically

rounded with 7–8 discal, and 17–20 marginal, too-

th-like outer ovisensillae; trichoid-like inner ovi-

Figures 4-10. Terminalia of Drosophila sagittifolii sp. nov. 4-8) Male Terminalia of Holotype: 4) Epandrium, Cerci,

Surstylus; 5) Hypandrium; 6) edeagus dorsal view; 7) Aedeagus Lateral View; 8) Aedeagus Ventral View; 9-10) Fe-

male Terminalia of Alotype: 9) Oviscapt Valve; 10) Inner Spermathecal Capsule. Scale bar: 3-8) 0.1mm, 9) 0.05 mm

A New Species of Drosophila associated to X. sagittifolium

Llangarí and Rafael

sensillae: 3 thin distally positioned, and 1 long,

slightly curved, subterminal. Spermathecae (Fi-

gure 10) nger-shaped, small and membranous.

Egg.- Oval-shaped with four long, curved laments.

Etymology.- This species is named in re-

cognition of its presumed primary lar-

val host plant, Xanthosoma sagittifolium.

Biology.- Adults of D. sagittifolii sp. nov. were

found only on Xanthosoma sagittifolium inores-

cences at the Río Guajalito Research Station. Eleven

individuals (four males and seven females) emer-

ged in the laboratory from three inorescences of

X. sagittifolium after 36 days in laboratory.

DISCUSSION

Drosophila sagittifolii sp. nov. belongs to

the genus Drosophila. Judging by the sha-

pe of the aedeagus, D. sagittifolii sp. nov.

could be related to Drosophila crassa, Patter-

son & Mainland, 1944 an ungrouped species

(Vilela and Bächli 1990) It is also similar to the

aedeagus of the Drosophila canalinea group

of species, such as Drosophila annulosa Vile-

la & Bachli, 1990 and Drosophila parannularis,

Vilela & Bachli, 1990. Although the collections of

Drosophila adults were from inorescences of An-

thurium spp. and X. sagittifolium, Drosophila sagit-

tifolii sp. nov. adults were only found from the X. sa-

gittifolium inorescences. The natural breeding and

larval feeding sites of the species in relation to owers

have not been studied sufciently. Drosophila

saggitifolii sp. nov. is not attracted to traps bai-

ted with fermented banana. This fact has been

corroborated simultaneously in the same pla-

ce and at the same time, 3 369 ies from 26 spe-

cies of Drosophila were captured using bana-

na baits fermented with baker’s yeast, and no

D. sagittifolii sp. nov. were found

(Cabezas 2012).

During these collections of D. sagittifolii sp.

nov. on the inorescences of X. sagittifolium,

three couples in copulation were captured and

individuals of the new species emerged from

the inorescences in the laboratory. This sug-

gests that X. sagittifolium is one of the natural

breeding and courting sites used by

D. sagittifolii sp. nov.

The determination of the natural fee-

ding and breeding sites of species in the

Drosophilidae family is not an easy task. The abun-

dance and frequency of the hosts/substrates used

and the existing faunal associations must be un-

derstood. Climatic and geographic factors will also

play a role in determining seasonality and range of

these species (Brncic 1983). Therefore, it is neces-

sary to continue to conduct phylogenetic, ecologi-

cal and geographical studies of both the Drosophila

species and its presumed host plant, Xanthosoma

sagittifolium, to establish the true interac-

tion between the insect and the inorescences.

ACKNOWLEDGEMENTS

The Pontical Catholic University of Ecuador -

nanced the projects: “Riqueza faunística del género

Drosophila PUCE 2011” N°. H13171, and “Diver-

sidad y Ecología del género Drosophila (Diptera,

Drosophilidae) en la Provincia de Pichincha” N°.

H19121. Dr. Jaime Jaramillo (†) and Elena Grijal-

va, B.S. collaborated on this research and allowed

us to work at the Río Guajalito Research Station.

The Ministry of Environment granted collection

permits No. 001-10 IC-FAU-DNB / MA and No.

001-11 IC-FAU-DNB / MA. María Beatriz Ca-

bezas assisted in the eld phase of the project.

The authors are grateful to

Dr. Clifford Keil for his review

and valuable comments on the manuscript.

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