Chironomus apicatus Johannsen 1932

Adult

Male and female.  Differs from the typical form [i.e. C. costatus] in having the fore basitarsus 1.85 times tibia in length (i.e. LR), the tarsi largely brown, only the two apical segments somewhat paler brown.  The mesonotal vittae are brownish.  Crossvein of wings brown.  Hypopygium as figured [below].  Length 5 mm.  Bred from larvae found in pools.

Illustration of the hypopygium of C. apicatus
From Johannsen (1932)

Additional data on anterior tarsi of type (thanks to Duncan Sivell, Natural History Museum): Ta1 twice the length of Ta2; Ta2-4 subequal but decreasing in length; Ta5 less than half the length of Ta4.
Anal point narrow at base; Inferior Volsella not reaching to the end of the anal point, but to about the middle of the gonostylus, which is illustrated as only moderately swollen and narrowing gently over about the distal half.  No information on the abdominal coloration but in view of Johannsen's statement that it is similar to C. costatus, it probably has a large brown transverse oval spot on most segments.

Fourth instar larva: A small plumosus-type, length about 9.0-10.5 mm (males).  Lateral projections about 170-240 µm, posterior pair of ventral tubules usually longer (ant. 0.83-1.04 mm; post. 0.90-1.08 mm).  Gular region pale to slightly darkened, frontoclypeus very slightly dark to dark.  Anal tubules long with a constriction near centre.  Mentum with generally sharp teeth, c2 teeth well separated (type II), 4th laterals hardly reduced (type I-II).  About 13-15 teeth in pecten epipharyngis. 3rd inner tooth of mandible almost completely separated (type II-III).
Described by Lenz (1937) only as "Plumosus-type".

Breeding in pools.  In Indonesia found in salt ponds and a pool at 29°C and pH2.83 (Lenz 1937).

Found: Type locality - Toba Dist., Samosir, Sumatra, INDONESIA, also Sigaol, Samosir.