Medium-sized to large larvae, 6-11 mm long. Whitish in colour, although some may have red tinge from haemoglobin. Head capsule oval; cephalic index 0.80-0.85. Dorsally S5 quite anterior, DP, S8 and S7 aligned (P. (Psilotanypus)) or distinctly angled to more posterior DP (P. (Holotanypus)); ventrally SSm medial to S9 and S10, VP posterolateral, SSm, S10, VP almost aligned.
About as long as mandible. Antennal ratio 3.5-5.0. Basal segment about 5x as long as basal width, with ring organ at 0.7; segment 2 about 3.5x as long as wide; segment 3 almost 2x as long as wide, about as long as apical segment. Style ending more or less level with segment 3, arising, in common with peg sensilla, at sides, below distal margin of segment 2. Blade about as long as flagellum or reaching only to last segment. Accessory blade about 2x as long as segment 2.
Slender, uniformly curved. Apical tooth dark, 3x as long as basal width, more than 25% length of mandible. Without any inner tooth; small to stronger, pointed accessory tooth on mola, adjacent to origin of seta subdentalis; mola distally expanded to large, broad, protruding tooth with apically-directed, bluntly-rounded apex; seta subdentalis about 1/2 length of apical tooth. Ventrolateral seta 1 mostly simple, 2 with 2 or 3 branches, 3 with 4 or 5 branches.
Basal segment of palp about 2.5 x as long as wide, with ring organ in middle.
With fringe of swim-setae. With 4 anal tubules. Procercus almost 4x as long as wide, with 12-18 apical setae. Posterior parapod with 13-16 claws, some with appressed points on inner margin; smallest claws simple, curved in some species, in others more or less broadly expanded and 1 claw with 2-3 teeth on inner side of 2 claws with 3-4 such teeth.
Procladius is closely related to Djalmabatista. The latter is recognizable, amongst other characters, by the very large accessory blade on the antenna, more than 2X length of flagellum, and the anterior parapods connected by a continuous band of spinules. Both genera differ from all other genera of Tanypodinae with a dorsomental tooth row, in the ligula being blackish-brown over the distal 1/2, and in the large, blunt, mandibular molar expansion.
Roback (1982) erected the subgenus Holotanypus for the Holarctic species formerly placed in Procladius s.str. The type species of the Procladius is described from Australia and does not fall into either of the subgenera, which are separable in all life stages. Vallenduuk and Moller-Pillot (2008) discuss identification issues amongst the European species, observing that most species belong to subgenus Holotanypus with P. choreus very widespread. A revision of the Palaearctic species remains urgently required.
Subgenera of Procladius
- 1. Apical point of paraligula large, at least 3x as long as middle point of outer side; side points unequal, often absent from inner side. Mesal 1/2 of pecten hypopharyngis with slender, closely adjacent teeth. Smaller claws of posterior parapod generally forming flat curve, never with inner teeth. Long claws of posterior parapod with elongate filamentous apex. Mostly larger species, body length 7-11 mm ... P. (Holotanypus)
- -- Apical point of paraligula small, about 2x as long as side points; side points similar in size, sometimes also present on inner side. Smaller claws of posterior parapod strongly arched, some with 3-4 large teeth. Long claws of posterior parapod with conventional attenuate apex. Mostly smaller species, body length 5-8 mm ... P. (Psilotanypus)
Epler (2001) keys some species segregates and discusses ecology of s.e. USA species.
Larvae of the majority of Procladius species prefer muddy substrata of standing or slowly flowing water bodies, especially ponds and small lakes. A few species also colonize the profundal zone of large, deep lakes.
The genus has a worldwide distribution with many species principally in the Holarctic. Eighteen species of P. (Holotanypus) and 3 of P. (Psilotanypus) are described from North America (Roback, 1971). It is impossible to estimate at present the number of species living in the Palaearctic. More than 60 names are available from Europe, but many are likely to be synonyms. Seven species are noted for Japan. P. (Psilotanypus) has been found in the Neotropics but seems to be absent from Australia. A larva allocated to P. (Holotanypus) is reported from India (Roback and Coffman, 1987). Presently P. (Procladius) seems to be restricted to Australia (Roback 1982c), South America (Roback 1982d) and Africa.