Cricotopus festivellus Kieffer, 1906:18

Cuppen, Hub, Gresens, Susan E. & Tempelman, David, 2020, DESCRIPTION OF THE LARVAE OF CRICOTOPUS FESTIVELLUS (KIEFFER 1906) AND CRICOTOPUS DIVERSUS (BOESEL 1983) WITH KEYS TO DISCRIMINATION OF LARVAL, PUPAL AND ADULT STAGES (DIPTERA: CHIRONOMIDAE) Abstract, CHIRONOMUS Journal of Chironomidae Research 33 (33), pp. 4-16 : 6-7

Cricotopus festivellus Kieffer, 1906:18

Cricotopus (Cricotopus) festivellus (Kieffer) , Hirvenoja, 1973:225

Description of larval C. festivellus : based on 4 th instar larvae (n = 3). Measurements of bilaterally symmetric structures are reported as mean values per specimen. Head capsule width 334-344 µm (n = 2).

Head capsule yellow, sometimes proximal part light brown. Postoccipital margin dark brown. Bifid S1 setae with branches of similar size; S2 seta simple ( Fig. 2A ). Antennae 5 segmented, Lauterborn organs well-developed and extending 2/3 – 3/4 the length of antennal segment 3. Total antennal length 85 – 90 µm. Antennal blade extends to last segment, accessory blade half that length. Antennal ratio 1.9-2.1, mean 2.0 (n = 3). Pecten epipharyngis composed of 3 scales. Mandible and 3 inner teeth, brown extending to molar area with wide pale base ( Fig. 2A ), length 136 µm. Outer margin of mandible smooth. Seta subdentalis yellow, ca. 2 times long as wide with a notched asymmetric tip which reaches the last free mandible tooth. Seta interna with 6 branches. Premandibula simple. Galea of maxilla with two or three rows of pectinate lamellae.

Mentum with 6 brown lateral teeth; median tooth projecting forward and at most 3 times wider than first lateral tooth; MR (width of median tooth/ width first lateral tooth ranges from 2.7-3.0, mean 2.85 (n = 3). VM-plate reaches1 st lateral tooth. Submental setae located at the level of the fourth lateral tooth of the mentum.

Middle-sized claws of the anterior parapods with inner teeth at most half as long as apical tooth ( Fig. 6B ). Abdominal segments 1 - 6 bear posterolateral setal tufts of 12-24 filaments. Length of tufts from 70 – 240 µm, reaching up to half to ¾ the length of the segment. Setal tufts on segment VII bear 8-10 setae which are shorter than the setae on I - VI. ( Fig. 3 ).

Procercus wider than long, bearing a sclerotized scale and 5-6 apical setae plus 2 fine lateral setae. Supra-anal setae 78 – 83 µm, as long or slightly longer as the anal tubules.

Pupa: The pupa of Cricotopus festivellus is described by Hirvenoja (1973) and Langton (1991). Exuviae light brown, characterized by frontal setae located on prefrons, 4 lateral setae on segment VIII with L4 not larger than the other lateral setae. Thoracic horn distally pointed and covered with small spinules. Pedes spurii B obvious on segment II but absent or weak on III. Tergite II usually with an extensive area of small spinules, variable, but at always at least bearing a transverse band of spinules anterior to the hooklet row. Tergites III-VI with median and posterior transverse bands of small points separated, but usually joined laterally, leaving a conspicuous median bare patch in the region of the posterior muscle marks.

Specimens examined: NTNU University Museum: 200820 (NO56), 200824 (NO60), 200826 (NO63), 200831 (NO73); H. Cuppen personal collection: 3 larvae, one with associated pex, 1 pex ( Table 1 ) .

DNA barcodes (BOLD Process IDs): BSCHI522-17, BSCHI708-17, BSCHI731-17, CHRFI512-11, CHRFI729-11, CHRSV514-11, CHRSV515-11, CHRSV517-11 = NO56, CHRSV521-11 = NO60, CHRSV524-11 = NO63, NEACH003-12 = NO73.

Figures

Figure 2. A) Cricotopus festivellus; mandible and premandible. Enschede, Landweerven, 18 May 2009. B) Cricotopus festivellus; epipharynx and S1. Veluwerandmeer, 5 October 2016.

Figure 3. Cricotopus festivellus; lateral tufts on segment 6 and 7. Veluwerandmeer, 5 October 2016.

Figure 6. A) Middle sized claws of anterior parapods of Cricotopus diversus. Oregon Ridge Park, Baismans Run, 11 September 2010. B) Middle claws of anterior parapods of Cricotopus festivellus. Veluwerandmeer, 5 October 2016.