Simulium (Inseliellum) adelaideae, Craig, Douglas A., 2004

Craig, Douglas A., 2004, Three new species of Inseliellum (Diptera: Simuliidae) from Polynesia, Zootaxa 450, pp. 1-18 : 3-6

Simulium (Inseliellum) adelaideae n. sp.

( Figs. 1–6 , 27 )

Types

Holotype

Larva: early penultimate instar as slide mount. Label data: “ Simulium (I) adelaideae . TAHITI. Above Lac Vaihiria, alt. 643 m. S17° 40.26’ W149° 25.33’. 30.viii.1998. Coll. D. A. Craig. HOLOTYPE. # 16523" (BPBM).

Diagnosis

Larva: head markedly brown and yellow, head spot pattern negative; apices of hypostomal teeth forming straight array with only median tooth protruding; postgenal cleft essentially absent; posterior arms of anal sclerite completely encircling base of posterior proleg, markedly so ventrally; accessory sclerites extended anteromedially

Description

Adult female (Unknown) Adult male (Unknown) Pupa (Unknown)

Larva (based on one mature penultimate instar larva)

Body: total length 5.8 mm; colour evenly greyish brown. Head ( Figs. 1, 2 ): width 0.9 mm, length 1.1 mm; distance between antennal bases 0.51 mm; head spots yellow, anterior of apotome pale yellow, remainder of cuticle rich brown; head margins convex, markedly so posteriorly; cervical sclerites fused to postocciput; setae numerous, length normal, sockets raised; cuticle markedly corrugated and rugose ( Fig. 3 ). Antenna: longer than labral­fan stem; total length 0.47 mm; distal article 0.13 mm; whole antenna markedly dark brown. Labral fan: fan stem light brown, hairy distally and posteriorly; 23 dark brown rays, 0.89 mm in length; 5–6 posterior rays finer than others, medial rays 0.02 mm wide; microtrichia 0.5 ray width, pattern of longer microtrichia with 7 subequal then two markedly smaller microtrichia between; ray apex extended. Postgenal bridge ( Fig. 2 ): 7 times longer than cleft depth; yellow anteriorly. Postgenal cleft: essentially absent, except for small V­shaped notch. Hypostoma ( Fig. 4 ): 17 teeth; prominent median tooth extended beyond others; sublateral teeth increased slightly in length laterally, but with tips in straight array; lateral teeth slightly longer than sublateral teeth; 1 paralateral tooth; 5–6 lateral serrations; 6 hypostomal setae per side. Mandible ( Fig. 5 ): only apical tooth well developed; spinous teeth markedly developed; serration prominent, basal sensillum distinct. Maxilla: lobe rounded; palpus 4 times longer than width—markedly developed ( Fig. 2 ). Mandibular phragma: extended ventrally to 0.3 depth of maxillary base. Abdomen: slightly amphora­shaped; posterodorsal cuticle not tuberculate, but with clear ovoid tubercles lateral of anal sclerite; sensilla trichoid, slightly elongated, sockets normal. Anal sclerite ( Fig. 6 ): well developed and darkly pigmented; median region expanded laterally, well pigmented, markedly hirsute with distinct clear sockets; accessory sclerites extended anteromedially almost to anterodorsal arms of anal sclerite; ventral arms extended around posterior proleg, substantially so ventrally. Posterior proleg circlet of hooks: with 110 rows of hooks, 15–16 hooks per row. Rectal papillae: three, with small basal papillae.

Additional material examined

None.

Etymology

Named after Adelaide, daughter of D. Joy and F. Elliott.

Comments

Superficially similar to S. cataractarum larvae, S. adelaideae differs noticeably in its enhanced head pattern and is perhaps the most colourful of all Inseliellum larvae, matched perhaps only by the head pattern of larval S. arlecchinum ( Craig and Joy 2000) . The number and arrangement of hypostomal teeth is similar to that seen in the hirticranium subgroup ( Craig and Joy 2000) and is reminiscent of that seen in the oviceps group. The virtually absent postgenal cleft is also shared with the hirticranium group, as is the development of the anal sclerite. The apical teeth of the mandible are also similar to those of S. hispidum . Absence of tubercles on the abdominal cuticle is shared with larvae of S. cataractarum and the hirticranium subgroup, except that S. adelaideae possesses tuberculate cuticle just anterior of the anal sclerite. Although sharing numbers of synapomorphic traits with the hirticranium subgroup, S. adelaideae does, however, not show the diagnostic elongated head setae possessed by larvae of that taxonomic segregate. Still, with its complement of character states, S. adelaideae will no doubt, after more detailed phylogenetic analysis, be shown to be related to S. cataractarum and probably basal to the hirticranium subgroup.

The type locality of S. adelaideae is the highest stream on the road that continues past and above Lac Vaihiria and through a tunnel to emerge in the Papenoo Valley. Fed by a small cascade the stream flows though dense vegetation before emerging ( Fig. 27 ) into sunlight, then crosses the road to plunge some 200 m down into the Lac Vaihiria Valley. With air temperature at 21° C, water temperature was 18° C, pH 8.4, and conductivity 50 µS. Water velocity was 76–98 cm /s and depth ca. 30 cm.

This small stream is unusual in the complement of species collected. Cascade­dwelling species ( S. cataractarum , S. dussertorum , S. fossatiae , S. oviceps ) probably originate from the cascade immediately upstream. Larvae of S. lotii and S. malardei , typical of smaller streams at lower altitude, were markedly larger than normal. Simulium cheesmanae adults were captured while trying to bite the author.

Figures

FIGURES 1 – 6. Simulium adelaideae, penultimate instar larva. 1. Dorsal view of head. Scale bar = 0.25 mm. 2. Ventral view of head. Scale bar = 0.25 mm. 3. Head cuticle and setae, showing corrugations and raised setal bases. Scale bar = 0.05 mm. 4. Hypostoma. Scale bar = 0.05. 5. Mandible. Scale bar = 0.05 mm. 6. Anal sclerite. Scale bar = 0.2 mm.

FIGURES 27 – 29. Type localities. 27. Simulium adelaideae. Above Lac Vaihiria on cross­Tahiti road. Larva collected in densely­shaded portion of stream in background. 28. S. sublonckei. Second cascade on road to Maroto River barrage, Vaitamanu Valley, Papenoo River catchment. 29. S. englundi. Unnamed stream, Mohotani Island, Hiva Oa, Marquesas Islands. Photograph courtesy of R. Englund.