Djalmabatista Fittkau

Description

Introduction

Small to medium-sized larvae, up to 6 mm long. Head pale, occipital margin pale. Head capsule oval; cephalic index 0.85. Dorsally with S7, S8 and DP near equidistant, S5 anterodorsal to S7. Ventrally SSm anteromedial or medial to S10, S9 directly anterior to S10, VP posterolateral to S10, either same distance from S10 as is S9, or more distant. All setae simple.

Antenna

About 3/4 length of mandible. Antennal ratio about 4. Basal segment about 4X as long as basal width, with ring organ at 0.7; segment 2 3X as long as wide; segment 3 more than 2X as long as wide, subequal to apical segment. Style ending beyond middle of segment 3, arising with short peg sensilla, at sides, below apical margin of segment 2. Blade very long, 2-5X length of flagellum; accessory blade very short, maximally reaching apex of segment 2.

Mandible

Strongly broadened basally, strongly curved apically. Apical tooth 2X as long as basal width, 1/4 length of mandible, without inner teeth. Mola with creases, strongly protruding as double tooth; ventral side with slightly smaller accessory tooth; seta subdentalis long. Ventrolateral seta 1 simple, 2 and 3 with 1-3 branches, 1 and 2 approximated, anteriorly displaced relative to Ring organ and basally-located seta 3.

Maxilla

Basal segment of palp 2X as long as wide, with ring organ at 0.4.

Body

With fringe of swim-setae. Anterior parapods united ventrally by connecting band of spinules; all but smallest claws with inner teeth. With 4 conical anal tubules. Procercus almost 4X as long as wide, with 10-11 apical setae. Posterior parapod with 16 pale brown claws; large claws with appressed points along inner side; small claws simply curved

Notes

Taxonomic Notes

Djalmabatista belongs with Procladius in the Procladiini. The curved mandible with large, crenate expanded mola, very long antennal blade and pale occipital margin characterise Djalmabatista. A further difference lies in the anterior parapods: in Djalmabatista, uniquely in the Tanypodinae, these parapods are linked ventrally by a continuous band of spinules: in Procladius, as in all other tanypods, the anterior parapod have independent crowns of claws, without such linking spinules.

Ecological Notes

Larvae of the only described Nearctic species, Djalmabatista pulchra, live in soft water or weakly acidic lakes and ponds and in slow flowing rivers in the eastern Nearctic from Canada to Florida. One or two more species are present including one from a desert spring in Arizona. The genus has not been found in the western Palaearctic but pupal exuviae have been found in a river in the transition zone between the Palaearctic and s.w. China. In Central America the widespread D. pulchra is reported and two undescribed species are known from Costa Rica. Many species of Djalmabatista are known the Neotropics, from which at present 6 described and perhaps many undescribed species occur. Exuviae of species belonging to this genus may regularly be encountered in the surface drift of large and small rivers in the Amazon basin. In Australia, larvae occur in warm temperate to tropical lentic and lotic depositional habitats, and prefer weakly to strongly acidic waters.

Djalmabatista reidi is the only described member of the genus in the Afrotropical region.

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