Simulium (Psaroniocompsa) oyapockense Floch and Abonnenc

Hernández, Luis Miguel, Shelley, Anthony John, Herzog, Marilza Maia - & Dias, Antonio Paulino Andrade Luna, 2011, Morphological variation in S. minusculum Lutz and S. oyapockense Floch and Abonnenc and a redescription of the larva of S. minusculum (Diptera, Simuliidae) in the Neotropical Region, Zootaxa 2863, pp. 35-48 : 42-45

Simulium (Psaroniocompsa) oyapockense Floch and Abonnenc

(Figs. 33–46)

This is a common, mainly anthropophilic species with a broad distribution within Brazil, but mainly around the northern tributaries of the Amazon River. It is one of the better–studied species because of its role as a primary vector of onchocerciasis in lowland areas of the Amazônia focus of the disease. A comprehensive overview of its taxonomy, morphology, distribution, biology and medical importance may be found in Shelley et al. (2010). Pupal cocoon morphology has been used as a diagnostic character at species level. The cocoon of S. oyapockense s.l. is typically slipper–shaped, but a form with a slightly shoe–shaped cocoon has been recorded in northern Brazil and is regarded by some authors as S. sanchezi Ramírez Pérez, Yarzábal & Peterson (see Shelley et al. 2006, 2010). We have now found S. oyapockense s.l. with both slipper– and shoe–shaped cocoons at a single site on the Araguaia River in Tocantins State, Brazil and these are described below and compared to topotypes and other populations of S. oyapockense s.l. with slipper-shaped cocoons typical for the species.

FEMALE.

Topotype S. oyapockense

Body size. Females [with slipper shaped cocoons]: Body length 2.3-2.6 mm (mean= 2.4 mm, s.d.= 0.14, n=4), wing length 1.6-2.3 mm (mean= 1.9 mm, s.d.=0.35, n=3), wing width 0.9-1.3 mm (n=2).

S. oyapockense Araguia Form

Body size. Females [with slipper shaped cocoons]: Body length 1.1–1.4 mm, wing length 1.2–1.3 mm, wing width 0.6–0.7 mm (n=2).

Females [with shoe–shaped cocoons]: Body length 1.2–1.8 mm (mean= 1.5 mm, s.d.=0.16, n=9), wing length 1.2–1.5 mm (mean= 1.4 mm, s.d.=0.56, n=9), wing width 0.6–0.8 mm (mean= 0.7 mm, s.d.=0.10, n=9).

Female [with intermediate slipper–shaped cocoon]. Body length not measured [specimen without head]; wing length 1.3 mm, wing width 0.6 mm (n=1).

The general morphology of females that emerged from mature pupae with slipper– (Figs. 33, 34), shoe– (Figs. 35, 36) and intermediate slipper–shoe shaped cocoons (Figs. 37, 38) from the Araguaia River agree with the description given in Shelley et al. (2010) for S. oyapockense s.l. We have dissected five females with shoe–shaped cocoons and the general morphology of the head, wing venation, leg coloration and genitalia agree with S. oyapockense as detailed in Shelley et al. (1997, 2006, 2010).

MALE.

Topotype S. oyapockense

Body size. Male [with slipper–shaped cocoons, following Shelley et al., 2010]: Topotype from R. Oyapock (pinned): body length 3.8 mm, wing length 2 mm, wing width 1.2 mm (n=1).

S. oyapockense Araguia Form

Body size. Males [with shoe–shaped cocoons]: Body length 1.2–1.8 mm (mean= 1.4 mm, s.d.=0.21, n=8); wing length 1.1–1.6 mm (mean= 1.4 mm, s.d. =0.15, n=8), wing width 0.6–0.9 mm (mean= 0.7 mm, s.d. =0.09, (n=8).

Thoracic pattern. We examined males with shoe–shaped cocoons from the Araguaia River. Their thoracic patterns (Figs. 39–42) agree with those found for S. oyapockense s.l. reared from pupae with slipper–shaped cocoons ( Shelley et al., 2006, 2010). We have dissected two males with shoe–shaped cocoons and the general morphology of the head, wing venation, legs coloration and genitalia is similar to S. oyapockense as detailed in Shelley et al. (1997; 2006; 2010).

PUPA. Type material (lectotype and paralectotypes). Paralectotypes from R. Oyapock.

Gill length 0.7–1.1 mm (mean=0.95, s.d.=0.14; n=5) [Other measurements not taken because material is mounted on slides].

Topotype S. oyapockense

The following dimensions are recorded by SHELLEY et al. (1997) for topotypes from R. Oyapock: Cocoon length dorsally 1.6–2.8 mm (mean= 2.1 mm; s.d.=0.3; n=25); ventrally 1.5–2.6 mm (mean = 2.0 mm; s.d.=0.2; n=26); pupa length 1.7–1.8 mm (n=2); gill length 0.7–1.5 mm (mean=1.0 mm, s.d.=0.2, n=20). [Extra data from Shelley et al. (2006); see this publication for statistical analysis] – Gill length 1.6–2.1 mm (mean= 1.8 mm, s.d.=0.2, n=5).

PLATE 5. Figs. 33–44. Adult thoracic patterns in S. oyapockense from reared specimens collected in the Aragauia River, Tocantins State, Brazil. The first figure shows anterior light direction and the second posterior light direction.33, 34: Female with slipper–shaped cocoon; 35, 36: Female with shoe–shaped cocoon; 37, 38: Female with intermediate slipper–shoe shaped cocoon; 39, 40: Male with slipper–shaped cocoon; 41, 42: Male with shoe–shaped cocoon.

PLATE 6. Figs. 43–46. Cocoon shape and gill configuration in S. oyapockense from specimens collected in Aragauia River, Tocantins State, Brazil. 43: Slipper–shaped cocoon (lateral view); 44: Shoe–shaped cocoon (lateral view); arrow indicates the configuration of the pupal gill filaments; 45: Cocoon with intermediate slipper–shoe shaped cocoon (lateral view); 46: Cocoon with intermediate slipper–shoe shaped cocoon (frontal view); arrow indicates the junction of the cocoon anterior aperture with the base of the cocoon.

All other localities in Brazil. [See Material Examined in Shelley et al., 2010]:

Cocoon length dorsally 1.6–2.3 mm (mean=2.0 mm, s.d.=0.2, n=10); ventrally 1.7–2.4 mm (mean= 2.1 mm, s.d.=0.2, n=10); pupa length 1.5–2.1 mm (mean= 1.9 mm, s.d. =0.2, n=10); gill length (longest intact filaments) 0.8–1.5 mm (mean=1.0 mm, s.d.=0.2, n=10).

S. oyapockense Araguia Form

Slipper-shaped cocoon

Cocoon length dorsally 1.7–1.8 mm (n=2); ventrally 1.7–2.4 mm (n=2); pupa length 1.8-2.1 mm (n=2); gill length 0.6–0.8 mm (n=2).

Shoe-shaped cocoon

Cocoon length dorsally 1.7–2.7 mm (mean= 2.1 mm; s.d. =0.28; n = 17); ventrally 2.0– 2.8 mm (mean = 2.5 mm; s.d. =0.22; n=17); pupa length 2.0– 3.1 mm (mean= 2.5 mm; s.d. =0.31 (n=17); gill length 0.7–1.2 mm (mean= 0.87 mm, s.d. =0.13, n=19).

Intermediate shaped cocoon

Cocoon length dorsally 1.7 mm (n = 1); ventrally 2.2 mm (n=1); pupa length 2.6 mm (n=1); gill length 0.8 (n=1).

The cocoon of the pupa of S. oyapockense is reported to be slipper–shaped (Fig. 43), which is diagnostic for this species ( Shelley et al., 1997, 2006, 2010). However, specimens from the Aragauia River, Tocantins State, Brazil mainly showed cocoons that were shoe–shaped (Fig. 44) and two specimens that were slipper-shaped and one that was intermediate between slipper– and shoe-shaped (Figs. 45, 46). Apart from this variation, the gill configuration (see Figs. 43, 44) and abdominal onchotaxy agree with descriptions in Shelley et al. (2010).

LARVA (Final instar). No larvae were examined from the Araguaia River.

Discussion. The complicated taxonomy of S. oyapockense s.l. has been reviewed by Shelley et al. (1997; 2006). More recently, Shelley et al. (2010) also dealt with this species and synonymised Cerqueirellum pydanieli Pessoa, Medeiros & Barbosa with S. oyapockense , which we follow in this paper.

The use of the cocoon shape as the only character to distinguish S. oyapockense s.l. from S. sanchezi was not accepted by Shelley et al. (2006), who synonymised the latter name with the former, an action not followed by all specialists. Our current data show that in a single population both pupal cocoon forms and an intermediate form occur and are conspecific. Consequently, the synonymy of S. sanchezi with S. oyapockense is confirmed.