Beebeomyia tuxtlaensis Hernández-Ortiz and Aguirre, 2015

Hernández-Ortiz, V. & Aguirre, A., 2015, A new species of the Neotropical genus Beebeomyia (Diptera: Richardiidae) with observations of its biology on Dieffenbachia oerstedii (Araceae), Journal of Natural History 49 (31), pp. 1877-1889 : 1880-1888

Beebeomyia tuxtlaensis Hernández-Ortiz and Aguirre , sp. nov.

( Figure 1A–I )

Type material

Holotype. Male MEXICO: Veracruz, San Andrés Tuxtla, Estación de Biología Tropical Los Tuxtlas 150 m, 09/X/2012, A. Aguirre, D. Rodríguez y C. Díaz, hosp: Dieffenbachia oerstedii ( IEXA 213007544 ).

Paratypes. MEXICO: Veracruz, San Andrés Tuxtla, Estación de Biología Tropical Los Tuxtlas 150 m, 09/X/2012, A. Aguirre, D. Rodríguez y C. Díaz, hosp: Dieffenbachia oerstedii (12 males, 11 females – IEXA 213007544 ) ; Veracruz, San Andrés Tuxtla, Estación de Biología Tropical Los Tuxtlas 150 m, 22/XI/2012, A. Aguirre y D. Rodríguez, hosp: Dieffenbachia oerstedii (1 female IEXA 213007606 ) ; Veracruz, San Andrés Tuxtla, Estación de Biología Tropical Los Tuxtlas 150 m, 13/ IX/2013, V . Hernández, A. Aguirre y D. Rodríguez, hosp: Dieffenbachia oerstedii (49 males, 55 females IEXA 213007780 , CNIN, EBLT, USNM) .

Diagnosis

Beebeomyia tuxtlaensis sp. nov. can be distinguished from all other species of Beebeomyia by the following combination of characters: mesonotum entirely reddish, postpronotal lobe and notopleuron covered by whitish or grayish pollinosity; two dorsocentral setae, with anterior pair smaller; presutural supra-alar seta present; wing with small apical spot, costal and subcostal cells dark brown; foreleg yellow, including coxa to tarsomeres; mid and hind leg black with yellow; male with medial and lateral surstyli elongate of similar length in lateral view; phallus coiled with strong setae along basal third; distiphallus broad, with two comb-like opposite basal rows of long yellow setae; female aculeus length 0.80–0.84 mm, nearly two times as long as wide; apex of aculeus triangular, nearly two times longer than wide.

Description

Body length 5.36–6.25 mm ( Figure 1A ).

Head ( Figure 1B ). Height 1.06–1.22 mm, width in lateral view 0.88–1.04 mm. Frons shining reddish posterodorsally between vertex and ocellar triangle, matt anteroventrally from lunule almost to base of orbital seta. Face reddish yellow; first flagellomere reddish dorsally, somewhat darkened along apical half, reaching margin of clypeus; arista pubescent; occiput along posterior margin of eye with thin line of whitish pollinosity; gena narrow. A pair of long orbital seta located almost in line with ocellar setae; postocellar seta very small, inner and outer vertical setae present and similar sized; ventral margin of occiput, close to insertion of the head and thorax, with row of small black setae forming a fringe.

Thorax ( Figure 1C ). Mesonotum length 1.78–2.04 mm. Postpronotal lobe and mesonotum reddish, entirely covered by black setulae; whitish or grayish pollinosity covering postpronotal lobe and notopleuron; scutellum bare, subtriangular, yellow reddish, slightly paler than scutum; subscutellum reddish with small medial dark spot, mediotergite black; halteres whitish.

Macrosetae black as follows: 1 postprontal, 2 notopleural, 2 dorsocentral, with anterior pair smaller about one half length of posterior pair; 1 presutural supra-alar, 1 postsutural supra-alar, 1 intra-alar, 1 postalar, 2 scutellar, 1 anepisternal, acrostichal seta absent. Propleuron with one weak yellow seta; mesopleuron shining black, including anepisternum, anepimeron, katepisternum, with only yellow colouration surrounding anterior spiracle; pleuron surface mostly bare, with sparse and thin whitish pilosity.

Foreleg entirely yellow including coxa, anteroventral margin of distal part of femur without short spines, or with 1–2 subapical spines, posteroventral margin with row of 6–8 long black setae. Mid leg with femur mostly black, yellow apically, with 4–5 short ventral spines in two rows, tibia black, and tarsus yellow. Hind femur black except base and apex yellow, anteroventral margin with 2–3 spines slightly reduced, and posteroventral margin with 4–5 spines; tibia black, and tarsus yellow.

Wing ( Figure 1D ). Wing is 4.24–4.64 mm long, and 1.48–1.68 mm wide. Mostly hyaline except costal and subcostal cells entirely brown, a narrow apical dark spot, extended from apex of vein R 2+3 to apex of vein M; wing membrane evenly covered with microtrichia, except cell bcu completely bare, and cell bm basally bare on 3/4 of its length; base of vein R 4+5 with 2–3 small black setae; crossvein r-m located near mid-length of discal cell.

Abdomen. Shining black, with all tergites uniformly covered with black setulae, in addition to some noticeable transverse striations on tergites 3–5; syntergite 1 + 2 with 2 long black setae located on medial side, with a mid-transverse strip devoid of setulae.

Female genitalia ( Figures 1E–F ). Oviscape 0.86–0.92 mm long; aculeus length 0.80– 0.84 mm, and width 0.40–0.45 mm on wider section, nearly two times longer than wide; apex triangular (0.18–0.20 mm long), nearly as long as wide, yellow somewhat sclerotised, tip rounded.

Male genitalia ( Figures 1G–I ). Epandrium brown reddish; proctiger yellow; inner and outer surstyli approximately of same length in lateral view, inner surstylus with ventral triangular protuberance located just before mid-length, with short apical prensiseta; outer surstylus with mid-dorsal tooth-like projection, spoon-shaped apically; phallus long tangled, provided with numerous strong setae on basal third, the rest bare; distiphallus (or glans) broad, membranous, with two opposite basal comblike rows of long yellow setae; apical extreme membranous and translucent with two projections, an acute thorn weakly sclerotised, and other non-sclerotised bulbous projection.

Etymology

The specific epithet comes from the Mexican native word ‘Los Tuxtlas’, in addition to the Latin suffix ensis = coming from, in reference to the region of origin of the material examined.

Infestation rates and biology

Along with Beebeomyia tuxtlaensis , we also found another fly species of the family Drosophilidae , as yet unidentified, whose larvae were feeding simultaneously within the inflorescences of D. oerstedii . We assessed the infestation levels by the two species along sexual sections of the inflorescences. As a global infestation produced by larvae and pupae on 36 inflorescences, we found 1901 individuals of B. tuxtlaensis distributed on 20.5% and 79.5% of the male and female sections, respectively; while the drosophilid species accounted for 370 individuals distributed on 55.7% and 44.3% along the male and female sections, respectively.

Infestation levels of the male section (upper) compared between the two fly species were not statistically different (Wilcoxon test, Z = 1.21, N = 36 inflorescences, P = 0.225); B. tuxtlaensis presented 10.83 ± 2.81 (individuals mean ± SE), while drosophilid species were 5.72 ± 1.4 (individuals mean ± SE) ( Figure 2A ). However, in the female section (bottom), higher infestations by B. tuxtlaensis were found (41.97 ± 1.4, mean ± SE) with respect to the drosophilid species (4.55 ± 1.0, mean ± SE) (Wilcoxon test, Z = 4.53, N = 36 inflorescences, P = 0.000) ( Figure 2B ). Results of the distribution of B. tuxtlaensis among the inflorescences showed greater infestation levels in the female section (Wilcoxon test, Z = 3.81, N = 36 inflorescences, P = 0.000), while the drosophilid species did not show significant differences of infestation levels between sexual sections (Wilcoxon test, Z = 0.84, N = 36 inflorescences, P = 0.396).

In Beebeomyia tuxtlaensis , the average time of development for the larval stage was 27.7 days, whereas for pupal stage it was 14.3 days; therefore, the expended time from the collection of larvae to adult emergence was of 42 ± 1.02 days (mean ± SE, N = 42 individuals); however, for the drosophilid species, the expended time from the collection of larvae to adult emergence was of 16.47 ± 0.86 days (mean ± SE, N = 40 individuals).

In addition, two hymenopteran parasitoid species were associated with B. tuxtlaensis , one species of the family Eulophidae , represented by a gregarious parasitoid recovered from 13 pupae; and three pteromalid specimens ( Pteromalidae sp. 1) recovered from the same number of pupae. The drosophilid species was also parasitised by three hymenopteran species; a solitary parasitoid of the family Figitidae recovered from 25 pupae, nine parasitoids of Pteromalidae sp. 2 and four parasitoids of Pteromalidae sp. 3.

The biology of the Richardiidae is poorly known. The majority of known larvae are saprophagous, found in decaying vegetable matter ( Hancock 2010). Only a few species have been recorded as having phytophagous larvae, such as Sepsisoma erythrocephalum (Schiner) which damages the stems of grasses ( Deeming 1985), and Melanoloma viatrix Hendel and M. canospila with larvae associated with damage of pineapple fruits in South America ( Peñaranda and Ospina 1995; Hancock 2010). Larvae of an unidentified species of Melanoloma were also observed in inflorescences of Taccarum ulei Engl. & K. Krause (Araceae) in Brazil, feeding on the connectives of male florets and fruits ( Maia et al. 2013).

Seifert and Seifert (1976) reported an unidentified Beebeomyia species associated with Heliconia imbricata (Kuntze) Baker , and H. wagneriana Peterson (Musaceae) in Costa Rica. Some observations showed that flower parts, particularly the petals, and nectar seem to be the main food source; oviposition occurs on the rachis or inside the bract near the juncture of the rachis and bract. Larvae occasionally were found in H. latispatha Benth. and adults were observed copulating, as well as near H. imbricata and H. wagneriana . Other records include an unidentified Beebeomyia species as saprophagous, most living between buds and bracts of H. imbricata ( Naeem 1990) , and also in H. bihai in Venezuela ( Frank and Barrera 2010). Richardiid flies have been recorded as visitors of Dieffenbachia nitidipetiolata ( Garcia-Robledo et al. 2005) , and several undescribed Beebeomyia species from Costa Rica have been reared from flowers and bracts of Anthurium (Araceae) and Heliconia (Musaceae) species ( Hancock 2010).

The oviposition behaviour of Beebeomyia tuxtlaensis was recorded in its natural environment. Adult females were observed on developing inflorescences, when they were still closed; conversely, we did not observe any adult male either on inflorescences or elsewhere on the host plant, indicating that mating may occur on other plants. After a female lands on the inflorescence, it moves from top to bottom for inspection, and then begins to deposit individual eggs. This is done repeatedly, with dozens of eggs hatching throughout the inner edge of bracts ( Figures 3A–E ).

Upon completion of the oviposition process, the female moves once again up and down the inflorescence, exposing her aculeus and dragging it along the entire length of the structure, which most likely indicates that a deterrent pheromone is left to prevent further oviposition by other conspecific females. The eggs were incubated at the inner edge of closed bracts and usually remained in the open bracts with numerous eggs along the border. The larvae and pupae were both found in the upper section of the male inflorescence, feeding on the rachis, causing its decay ( Figures 4 A-C). Furthermore, larvae of Beebeomyia were also found feeding at the bottom in the female section, and pupae were found arranged in small groups housed into the bract ( Figures 5A–D ).

Figures

Figure 1. Adult morphology of Beebeomyia tuxtlaensis n. sp.: (A) general habitus of male, lateral view; (B) detail of head; (C) thorax, dorsal view; (D) wing pattern and venation; (E–F) morphology of the female ovipositor and the aculeus tip; (G) male terminalia in lateral view showing outer and medial surstyli; (H–I) male phallus showing basal spines and detail of the distiphallus.

Figure 2. Assessment of the infestation levels produced by B. tuxtlaensis and a drosophilid species on (A) the male and (B) the female sections of the inflorescence of D. oerstedii.

Figure 3. (A) general aspect of the host plant, D. oerstedii, showing flower buds open and closed; (B) distribution of the male (top) and female (bottom) flowers in the inflorescence; (C) flower bud with eggs located at the edge of the bract; (D–E) females of Beebeomyia tuxtlaensis ovipositing on the bud. Arrows show the eggs.

Figure 4. Detail of male section of the inflorescence of D. oerstedii. (A) flower bud open with eggs of Beebeomyia exposed on the edge of the bract; (B–C) larvae of Beebeomyia feeding on the male flowers and damage along the raquis. Arrows show eggs (A) and larvae (B, C).

Figure 5. Detail of female section of the inflorescence of D. oerstedii. (A) cross section showing the female flowers; (B–C) damage produced by larvae of Beebeomyia inside the female flowers; (D) some ovaries damaged by the larvae, and pupae arranged in groups inside the bract. Arrows show larvae and pupae.