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

Craig, Douglas A., 2004, Three new species of Inseliellum (Diptera: Simuliidae) from Polynesia, Zootaxa 450, pp. 1-18 : 6-10

Simulium (Inseliellum) sublonckei n. sp.

Figs. 7–12 , 15 , 28

Types

Holotype

Larva: Last instar: in alcohol. Label data: " Simulium (I) sublonckei Craig. TAHITI, Vaitamanu Valley, 2nd cascade, alt. 325 m. S17° 37.51’ W149° 26.20’. 12­xi­2000. Coll. D. A. and R. E. G. Craig. HOLOTYPE #16525" (BPBM).

Paratypes

Larvae: Penultimate instars in alcohol. Label data as for Holotype, but with “ PARATYPE ” (larvae. CNCI, BPBM, DAC, ROM).

Diagnosis

Larva: body densely covered dorsally with dark brown, ovoid tubercles, with sharp delimitation laterally and pale median line on thorax; head markedly convex posteriorly, not markedly narrowed anteriorly; setae numerous, sockets raised; stemmata distinctly bulged laterally; labral fan stems well developed; 23 substantial labral fan rays; posteroventral arms of anal sclerite extended laterally to form wing­like lobes.

Description

Adult Female (Unknown) Adult Male (Unknown) Larva (based on six last instar larvae). Body: total length 6.5–7.6 mm; colour dark brown dorsally, sharply delimited laterally, pale ventrally; pale median line on thorax. Head ( Fig. 15 ): width 0.86–0.93 mm, length 0.83–0.93 mm; distance between fan­stem bases 0.42 mm; colour evenly dark brown; head­spot pattern not obvious; frontoclypeal apotome narrowed posteriorly; head margins highly convex posteriorly, narrowed anteriorly, but not markedly; cervical sclerites fused to postocciput, but not to cephalic apotome; cuticle corrugated and slightly rugose; setae numerous, length normal, distinct dark raised sockets ( Fig. 8 ). Antenna: evenly dark brown; 0.42 mm long; basal article curved, distal article 0.12 mm long, extended just beyond apex of labral­fan stem. Labral fan: stem brown and markedly hairy; 23 rays, 0.7 mm in length, brown, 2–3 posterolateral rays finer than others, medial rays 0.02 mm in width, microtrichia of medial rays 0.8 times ray width, pattern of longer microtrichia with 14–15 smaller ones, decreased abruptly in length to next long one, pattern very distinct, apex of ray markedly extended. Postgenal cleft ( Fig. 8 ): markedly U­shaped, 0.6 times deep as wide; postgenal bridge 1.2 times longer than cleft depth. Hypostoma ( Fig. 9 ): 15 teeth, median tooth subequal in length to other teeth; adjacent sublateral teeth smaller; other sublateral teeth peg­like, subequal in length, apices forming curved line laterally; lateral teeth not distinct; 1 paralateral tooth; 2 lateral serrations; 9–10 hypostomal setae per side, some bases closely situated. Mandible ( Fig. 10 ): apical teeth heavily sclerotized and blunt; 8 substantial spinous teeth decreased abruptly in length to serration; serration basal width 1.2 times height, anterior convex edge 2.0 times longer than concave posterior edge; sensillum poorly developed. Mandibular phragma: extended ventrally to 0.3 of maxilla base. Maxilla: tapered, palpus 0.076 mm in length, 0.032 mm in basal width. Thorax: dark brown dorsally and laterally, median pale line anteriorly ( Fig. 15 ); sternum pale. Abdomen: segments I–IV narrower than thorax, not increased in size posteriorly; segments V–VII increased gradually to maximum width at segment VII, then decreased smoothly. Posteroventral tubercles absent. Posterodorsal cuticle with closely­packed, small, dark brown tubercles; setae numerous with raised dark sockets ( Fig. 11 ). Anal sclerite ( Fig. 12 ): junction between anterior and posterior arms heavily pigmented and massive, anterior arms short and sharply tapered; posterolateral arms extended laterally to form heavily tuberculate, wing­like lobes, junction with accessory sclerite tenuous; accessory sclerite heavily pigmented and extended anteriorly to form anterolateral sclerite; posterolateral arms 4.0 times longer than anterolateral arms and extended 0.6 distance around posterior proleg; cuticle surrounding sclerite markedly setose. Posterior proleg circlet of hooks: with 163 rows of hooks, 25–27 hooks per row. Rectal papillae: complex.

Additional material examined

Tahiti­nui. Vaitamanu Vly Rd, 2nd cscd. 400 m. 11­viii­1996. Coll. D. A. and R. E. G. Craig; 27­vii­1998. Coll. D. A. Craig and D. A. Joy; 13­xi­2000. S17° 47.72’ W149° 11.47’. Coll. D. A. and R. E. G. Craig (larvae. BPBM, DAC). Papenoo Valley, Marae cascade. 50 m. 26­vii­92. Coll. D. A. and R. E. G. Craig (larva. DAC). Vaihiria Valley, cascade. 228 m. 9­viii­1996. Coll. D. A. Craig and R. E. G. Craig (larvae. DAC). Tahinu River. 445 m. 10­viii­1996. Coll. D. A. Craig and R. E. G. Craig (larvae. DAC).

Tahiti­iti: 4 km west of Tautira, cascade. 4­iv­1988. Coll. D. A. Craig and S. Loncke (larva. DAC). Fauoro Valley, Tirahi River, cascade. 40 m. 29­iv­88. Coll. D. A. Craig (larva. DAC). Vaitepiha River, cascade. 40 m. S17° 46.61' W149° 10.68'. 1­viii­1998. Coll. D. A. Craig and D. A. Joy (larvae. DAC).

Etymology

Named for its probable basal phylogenetic relationship to S. lonckei .

Comments

Larvae of S. sublonckei are similar in colouration and shape to those of S. lonckei and initially difficult to distinguish. Indeed, a misidentification was made by Craig (1997) where his Figure 63 is not of the larval head of S. lonckei , but is that of S. sublonckei . Further, the Vaitamanu locality given by Craig and Joy (2000) for S. lonckei is actually that for S. sublonckei . Larvae of both of these species are also similar to those of S. joyae ( Fig 14 ), but they can be distinguished by the sharp lateral cut­off of the abdominal dorsal pigmentation and cuticular tubercles, the distinct pale ecdysial line on the anterior thorax, a broader anterior head, labral fans with more rays and a distinct medial hypostomal tooth. Simulium sublonckei with broader anterior and posterior cephalic apotome (cf. Figs. 13– 15 ), would appear to be the more plesiomorphic of these three related species.

Similar in habitat preference to S. lonckei and S. joyae , S. sublonckei is found only in cascades ( Fig. 28 ). It occurs on both Tahiti­nui and Tahiti­iti, as does also S. joyae . At present, S. lonckei is known only from cascades on Tahiti­iti, a point of possible biogeographic significance.

The type locality cascade of S. sublonckei has been well collected over the years (e.g., Craig and Joy 2000, Craig 2001). With a preponderance of larvae of S. cataractarum , those of other species collected are S. arlecchinum , S. dussertorum , S. fararae , S. fossatiae , S. hirticranium , S. malardei , S. oviceps and S. neoviceps . With ten species this cascade has the greatest richness of any Tahitian locality ( Craig 1997, 2001), however, in comparison to simuliid habitats elsewhere ( Adler et al. 2004), it is not unusual.

Figures

FIGURES 7 – 12. Simulium sublonckei. 7. Pupal gills. Scale bar = 0.2 mm. 8. Hypostoma and postgenal cleft. Scale bar = 0.1 mm. 9. Hypostomal teeth. Scale bar = 0.1 mm. 10. Mandible. Scale bar = 0.05 mm. 11. Posterodorsal abdominal cuticle. Scale bar = 0.05 mm. 12. Anal sclerite. Scale bar = 0.2 mm.

FIGURES 13 – 15. Larval heads. 13. Simulium lonckei (last instar). 14. S. joyae (penultimate instar). 15. S. sublonckei (last instar). 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.