Ablabesmyia Johannsen

Description

Introduction

Medium-sized to large larvae, up to 11 mm long. Head yellowish-brownish, with dark basal margin; body yellowish to brown, sometimes with darker spots. Head capsule rather long, weakly oval; cephalic index 0.60-0.65. Dorsally, DP present, S5 located quite posteriorly; line between S8-S7 and S5-DP angled, or S8 and S7 aligned with DP and S5 [A. (Asayia)]. Ventrally, VP located posterior to S9, mesial to S10; VP only aligned with SSm, S10 in A. (Asayia). Setae multibranched, except for simple S8.

Antenna

Almost 1/2 as long as head, 3x as long as mandible. Antennal ratio 3.8-5.0. Basal segment about 18x as long as basal width, with ring organ at 0.5-0.6; segment 2 about 13x as long as wide; segment 3 2x as long as terminal segment. Style sclerotized in basal 1/2, extending to middle of last segment. Peg sensilla very small. Blade and accessory blade as long as basal segment or extending somewhat beyond flagellum; basal ring about 3x as high as wide, indistinct.

Mandible

Uniformly tapered and curved towards apex. Apical tooth 3x as long as basal width, not quite 1/4 length of mandible; distal 1/2 blackish brown. Large, bluntly rounded inner tooth, partly overlying seta subdentalis; mola produce into large blunt-ended or apically-directed pointed tooth; seta subdentalis long, thick. Ventrolateral setae all simple, situated adjacently in middle 1/3 of basal 1/2 of mandible; seta 1 much smaller than others, situated close to seta 2; ring organ proximal to seta 3 about same distance from SIII and SII is from SIII.

Maxilla

Basal palp subdivided into 2-6 segments; ring organ situated in intersegmental region between 2 apical segments; membranous palpiger may be long.

Body

Without fringe of swim-setae. Anal tubules slender, spindle-shaped, 4-5x as long as wide. Subbasal seta of posterior parapod simple. Procercus 2.3-3.7x as long as wide or 6.9-8.2 (A. (Asayia)), with 6 or 7 pale apical setae. Claws of posterior parapod simple, 13-16; larger claws with fine points on inner and/or outer margin; colour of claws yellowish, 1-3 of smaller claws dark brown to blackish brown (all claws more or less similarly pale in A. (Asayia)).

Notes

Taxonomic Notes

Ablabesmyia may be the most species-rich genus of the Tanypodinae. Especially characteristic larval features of Ablabesmyia include the usual 1-3 dark posterior parapod claws, the subdivision of basal segment of the maxillary palp into 2-6 parts, with the ring organ situated between the distal 2, and also the unequal-sized pecten hypopharyngeal teeth. The divided palp of Paramerina is only ever in 2 sections with the basal shorter than apical: in this genus the cephalic setae SSm, S9 and S10 are aligned transversely and DP is absent, differing markedly from the pattern in Ablabesmyia (Stur and Fittkau, 1997). Four subgenera were erected principally on their imaginal stages (Roback 1985); incorporation of features of pupae and larvae allowed Oliveira et al. (2008) to key all stages of the four groups.

Keys

Subgenera of Ablamesmyia

    • 1. Maxillary palp with 3 or more sclerotized segments. Cosmopolitan ... Ablabesmyia (s.s.)
    • -- Maxillary palp with 2 sclerotized segments ... 2
    • 2. Procercus length:width 6.9-8.2; toothed margin of ligula straight and middle three teeth truncated. All posterior parapod claws pale. Nearctic ... Ablabesmyia (Asayia)
    • -- Procercus length:width <3.7; toothed margin of ligula concave, if straight then middle three teeth pointed. Some posterior parapod claws darkened ... 3
    • 3. Procercus length:width 2.3-3.4, with 7 apical setae (Worldwide) ... Ablabesmyia (Karelia)
    • -- Procercus length:width 3.2-3.7, with 6 apical setae (Neotropical) ... Ablabesmyia (Sartaia)


Epler (2001) keys 3 subgenera and 12 species of s.e. USA Ablabesmyia and provides notes on discrimination, corrections to other works, and their distributions. Vallenduuk and Moller-Pillot (2008) discuss identification of the 3 western European species.

Ecological Notes

Ablabesmyia is eurytopic and cosmopolitan: larvae inhabit small and large standing and flowing waters from cold temperate to warm tropical climatic zones. Late instar larvae are predatory, perhaps especially on smaller chironomid larvae and oligochaetes which are engulfed. Lentic larvae live in shallow water as well as in deeper regions of lakes. Individual species may occupy very varied habitats, and may include tolerant and sensitive species to acidity and humic content. Vallenduuk and Moller-Pillot (2008) discuss the ecology in western Europe. The larvae of Ablabesmyia janta live symbiotically in Unionidae mussels (Roback, 1982b).

The highest diversity of Ablabesmyia seems to be in the tropics and warm temperate zones. Four species are known from the Palaearctic, with A. monilis and A. longistyla, widespread, including in Japan (Kobayashi and Kubota, 2002), A. phatta (western Palaearctic) and A. prorasha described by Kobayashi and Kubota (2002) for some misidentified A. monilis in Japan and Korea. In the Nearctic some 13 species in three subgenera are recognised. Some Nearctic or MesoAmerican species are recorded from the northern neotropics including A. cinctipes (Johannsen) from Mexico, Belize and Guatemala, and A. costarricensis (Picado) from bromeliad phytotelmata. Ablabesmyia (Sartaia) is thus far known only from the Neotropical Region (Oliveira et al, 2008). Five species are described from Argentina and Chile, including A. reissi. Although larvae of Ablabesmyia are reported often from Brazil, only recently has a named species been described (Ablabesmyia oliveirai). Two species groups, A. notata (2-segmented palp) and A. hilli (multi-segmented palp) are recognised from Australia, and both occur also in s.e. Asia.

Four subgenera have been recognised: A. (Ablabesmyia) has a worldwide distribution; A. (Karelia) is recognised from the Holarctic, Neotropical, Oriental and Afrotropical regions; A. (Sartaia) for A. metica is known only from the Neotropics and A. (Asayia) was described for the Nearctic A. annulata (a Neotropical record is unsubstantiated).

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