Pentaneurella katterjokki Fittkau & Murray, 1983

Laurindo da Silva, Fabio & Stur, Elisabeth, 2019, Pentaneurellakatterjokki Fittkau & Murray (Chironomidae, Tanypodinae): redescription and phylogenetic position, ZooKeys 833, pp. 107-119 : 107

Pentaneurella katterjokki Fittkau & Murray, 1983

Pentaneura spec. Katterjokk Fittkau, 1962: 372 (description of male)

Pentaneurella katterjokki Fittkau & Murray, 1983: 62 (description of male and immature stages)

Material examined.

Type material: Holotype pharate male (ZSM slide A and B), SWEDEN, Katterjokk, Swedish Lappland, leg. L. Brundin. Two paratypes: pharate female and larva data as for holotype.

Additional material: NORWAY, Oppland, Rondane National Park: Adult male (NTNU-VM slide 201765), Skranglehaugen (P4), 1110 m asl, 61.98270N, 9.80360E, 14-21.vii.2008, leg. T. Ekrem, [BOLD ID: ATNA328]. Adult male (NTNU-VM slide 201767), as previous except for Skranglehaugen (P3), 1115 m asl, 61.98219N, 9.80451E, [BOLD ID: ATNA333]. Adult female (NTNU-VM slide 201768), as previous except for 07-14.vii.2008, leg. T. Hoffstad, [BOLD ID: ATNA335]. Adult female (NTNU-VM slide 201766), Skranglehaugen (P2), 1119 m asl, 61.98141N, 9.80480E, 14-21.vii.2008, leg. T. Ekrem, [BOLD ID: ATNA 331]. Pupa (NTNU-VM slide 201769), Skranglehaugen (P5), 1105 m asl, 61.98346N, 9.80384E, 07-14.vii.2008, leg. T. Hoffstad, [BOLD ID: ATNA338]. Larva (NTNU-VM slide 201764) Skranglehaugen, 1117 m asl, benthos, 61.99186N, 9.80454E, 23.vi.2008, leg. E. Stur, [BOLD ID: ATNA122]. Pupa (NTNU-VM slide 201771) Dørålseter, 1032 m asl, kick sample 3, 61.99347N, 9.80343E, 10.viii.2015, leg. K. Hårsaker, T. Ekrem and M. Majaneva, [BOLD ID: EBAI-Ch122]. Larva (NTNU-VM slide 201770) as previous, [BOLD ID: EBAI-Ch66]. GERMANY, Bayern, Berchtesgaden National Park: Adult male, (NTNU-VM slide 201774), Herrenrointquelle 308, 1250 m asl, 47.57778N, 12.97222E, 26.vii-09.viii.2005, leg. F. Eder, [BOLD ID: ES147]. Adult male, (NTNU-VM slide 201772), Schapbachquelle 360a, 1140 m asl, 47.58278N, 12.95806E, 27.v.-14.vi.2005, leg. F. Eder, [BOLD ID: ES46]. Adult male, (NTNU-VM slide 201773), as previous except for 28.vi-12.vii.2005, leg. F. Eder & A. Schellmoser [BOLD ID: ES82].

Diagnostic characters.

Pentaneurella katterjokki differs from other Pentaneurini species by the combination of the following characters. Adult male: thorax with a scutal tubercle, tibial spur on fore leg with long outer tooth and shorter side teeth, anal point apically notched. Adult female: gonapophysis VIII triangular, tergite IX without setae, coxosternapodeme strongly curved, postgenital plate broadly rounded, labia with inconspicuous microtrichia. Pupa: plastron plate moderately large, corona absent, anal macrosetae with adhesive sheaths, genital sac symmetrically tapered. Larva: dorsally DP absent, peg sensilla large, firmly fused with the margin of antennal segment 2, forming a fork-like process.

Description.

Adult male (n = 3, except where otherwise stated).Size. Total length 5.2 (1) mm. Wing length 3.0-3.1 mm. Total length/wing length 1.75 (1). Wing length/profemur length 2.09-2.22 (2).

General coloration. Head pale brown with darker occipital margin; pedicel and antenna brown; maxillary palp pale brown. Thorax pale brown. Wing membrane transparent without marks. Legs brown to pale brown. Abdominal tergite I–VI white, T VII with continuous pale brown transverse band near proximal margin, VIII pale brown; hypopygium pale brown.

Head. Temporal setae 17-19, uniserial. Eye ratio 0.47-0.59. Tentorium 235-289 μm long. Clypeus 132-189 μm long, 97-111 μm wide at widest part, bearing 12-22 setae. Cibarial pump 284-301 μm long. Lengths of palpomeres 1-5 (in μm): 77-82; 84-97; 163-178; 171-207; 324-342. Antenna 1250-1297 μm long, diameter of pedicel 185-188 (2) μm. AR 1.22-1.31.

Thorax. Antepronotals 6-10. Acrostichals 30-52, double staggered row which diverges posteriorly to join the dorsocentral row; dorsocentrals 24-38, biserial anteriorly and uniserial posteriorly; prealars 11-12 (2); supraalar 1 (1). Anapleural suture ratio 0.48-0.55. Scutellars 10-14. Scutal tubercle present.

Wing (Fig. 1A). Width 0.85-0.86 (4) mm. Membrane densely covered with macrotrichia. Costa 2.9-3.1 (4) mm long without extension ending proximal to R4+5; MCu almost at FCu; R2+3 present, R3 not reaching costa. VR 0.91-1.05. WW 0.27-0.29. Brachiolum with 3 setae. Squama with 18-26 (2) setae. Anal lobe moderately developed.

Legs (Fig. 1 B–E). Fore leg: width at apex of tibia 70 (2) μm, tibia with single, apical and pectinate spur 36-37 (2) μm long (Fig. 1B), with 4 (2) lateral teeth; ta1-4 without preapical pseudospurs. Mid leg: width at apex of tibia 64-72 μm, tibia with two apical spurs 22-27; 32-40 μm long (Fig. 1C), with 4-5 lateral teeth; ta1-4 with preapical pseudospurs. Hind leg: width at apex of tibia 62-72 μm, tibia with two apical spurs 22-29; 25-29 μm long (Fig. 1D), with 4 lateral teeth; comb not observed; ta1-4 without preapical pseudospurs. Claws slender, distally recurved and pointed and with large basal protuberance (Fig. 1E). Pulvilli absent. Lengths and proportion of leg segments as in Table 1.

Hypopygium (Fig. 1F). Tergite IX slightly concave posteriorly, without posterior setae. Membranous anal point broad, apically notched. Phallapodeme 106-130 (2) μm long. Sternapodeme with reduced anterior process. Gonocoxite cylindrical, 235-285 μm long, 103-131 μm wide. GcR 2.02-2.44. Gonostylus slender, 166-176 μm long, megaseta cochleariform, 14-17 μm long. HR 1.44-1.62. HV 3.04 (1).

Adult female (n = 2, except where otherwise stated). Size. Total length 5.2 (1) mm. Wing length 3.3-3.4 mm. Total length/wing length 1.02-1.14. Wing length/profemur length 2.55-2.74.

General coloration. Head pale brown with darker occipital margin; pedicel and antenna brown; maxillary palp pale brown. Thorax pale brown. Wing membrane transparent without marks. Legs brown to pale brown. Abdominal tergites and genitalia pale brown.

Head. Temporal setae 22-24, irregularly uniserial. Eye ratio 1.12-1.33. Tentorium 186-287 μm long. Clypeus 157-176 μm long, 108-121 μm wide at largest part, bearing 25-28 setae. Cibarial pump 281-305 μm long. Lengths of palpomeres 1-5 (in μm): 52-57; 98-102; 180-181; 188-193; 333-334. Antenna 897-920 μm long, diameter of pedicel 98-100 μm. AR 0.36-0.39.

Thorax. Antepronotals 7. Acrostichals 44-48, double staggered row which diverges posteriorly to join the dorsocentral row of setae; dorsocentrals 36-48, biserial anteriorly and uniserial posteriorly; prealars 15-16; supraalars 2. Anapleural suture ratio 0.49 (1). Scutellars 8-10. Scutal tubercle present.

Wing. Width 1.00-1.10 mm. Costa 3.3-3.4 mm long. VR 0.96-0.98. WW 0.30-0.31. Brachiolum with 3 setae. Squama with 22-25 setae.

Legs. Fore leg: width at apex of tibia 71-74 μm, tibia with single, apical and pectinate spur 27-28 μm long, with 4 lateral teeth; ta1-4 without preapical pseudospurs. Mid leg: width at apex of tibia 54-68 μm, tibia with two apical spurs 27-28; 29-32 μm long, with 4-5 lateral teeth; ta1-4 with preapical pseudospurs. Hind leg: width at apex of tibia 65-67 μm, tibia with two apical spurs 30-35; 44-48 μm long, with 4 lateral teeth; comb not observed; ta1-4 without preapical pseudospurs. Claws slender, distally recurved and pointed and with large basal protuberance. Lengths and proportion of leg segments as in Table 2.

Genitalia (Fig. 1 G–H). Gonapophysis VIII triangular, 84-85 μm long. Tergite IX without setae. Coxosternapodeme 142-159 μm long. Postgenital plate broadly rounded. Cerci oval-quadrate, 55-63 μm long, 24-31 μm wide; with 20 elongated setae. Labia with inconspicuous microtrichia. Notum 196-199 μm long. Seminal capsules oblong, 74-75 μm long, 55-69 μm wide, with conical shaped necks. Length ratio SCa/No 0.37-0.38.

Pupa (n = 2, except where otherwise stated).Size. Abdomen 3.5-4.3 mm long in male.

General coloration. Exuviae mostly pale brown without any distinctive patterns; thoracic horn brown.

Cephalothorax (Fig. 2A). Wing sheath smooth, 1.5-1.6 mm long. Thoracic horn 322-336 μm long and 111-115 μm wide (Fig. 2A). THR 2.89-2.93. Respiratory atrium almost filling the lumen cavity, apically constricted into a narrow, short and straight neck, connected basally to a large rounded plastron plate. External membrane with spinules basally interconnected, forming scales. Basal lobe large apically round. Thoracic comb with 14 or 15 conical tubercles (Fig. 2A).

Abdomen (Fig. 2B, C). Tergite I with scar 217-238 μm long. Shagreen on tergites very sparse, spinules only present on the anterior median border of tergite VII, anterior and posterior borders of tergite VIII and sparsely on the anal lobe. Sternites I and VIII without shagreen, S II–VI with lateral longitudinal narrow bands or shagreen, S VII almost entirely covered with shagreen. Abdominal chaetotaxy as in figure 2B. Abdominal segment VII with 4 LS-setae. A VIII with 5 LS-setae. Anal lobe 516-533 μm long, 319-331 μm wide (Fig. 2C). ALR 1.60-1.62. Male genital sac not surpassing apex of anal lobe.

4th instar larva (n = 2, except where otherwise stated).General coloration. Head golden yellow, postoccipital margin brown. Ligula pale yellow, with apex brown. Abdomen pale yellow. Procercus pale brown along anterior margin.

Head (Fig. 3A). Length 808-873 μm, 495-518 μm wide; IC 0.59-0.61. Dorsally DP absent, S5 and S8 postero-mesal to S7. Ventrally S9, S10 and SSm forming a gently curved line (Fig. 3A).

Antenna (Fig. 3 B–C). Length 374-383 μm, A1 274-276 μm long, with ring organ located 0.44-0.54 from base, A2 86-93 μm long. Peg sensilla large, firmly fused with margin of antennal segment 2, forming a fork-like process (Fig. 3C). AR 2.57-2.73. Blade 104-106 μm long.

Maxilla (Fig. 3D). Basal palp segment 59-60 μm long, 12-13 wide at middle, with ring organ located 0.40-0.68 from base. PR 4.44-4.45. APR 4.59-4.66.

Mandible (Fig. 3E). Length 95-115 μm. Sensillum campaniformium located 0.72 from apex. AMD 2.38- 2.89.

Mentum and M appendage (Fig. 3F). Dorsomentum sclerotised, without teeth. Labial vesicles oblong. Pseudoradula with fine granulation, not arranged in distinct longitudinal rows, 115 (1) μm long.

Hypopharyngeal complex (Fig. 3 G–H). Ligula with 5 teeth, 86-98 μm long, 44-52 μm wide at base; row of teeth slightly concave, middle and inner teeth subequal in size, outer slightly larger; inner teeth curved outward (Fig. 3G). IO 0.98-1.02, MO 0.98-1.00. Paraligula bifid, 36-47 μm long, inner tooth 29-36 μm long. Pecten hypopharyngis with 14-15 subequal teeth, corner tooth and middle teeth slightly broader than remainder (Fig. 3H).

Body (Fig. 3I). Without fringe of swim-setae. Procercus 153-182 μm long, 54-71 μm wide, with 6 anal setae 680-760 μm long. L/W 2.56-2.83. Anal tubules slender, 311-341 μm long. Posterior parapod 671-695 μm long. Claws simple (Fig. 3I), some with small spines on inner and/or outer margin.

Systematics.

In their comprehensive analyses of the Chironomidae subfamily Tanypodinae, Silva and Ekrem (2016) considered morphological characters across all life stages for all nine tribes within the subfamily, involving 54 genera and 115 species. In their study, Silva and Ekrem suggested that Paramerina Fittkau, Reomyia Roback and Schineriella Murray & Fittkau should be subgenera in Zavrelimyia . In addition, Pentaneurella was recovered as sister to Trissopelopia Kieffer in both analyses of equally weighted characters and by using implied weights. However, in an ongoing phylogenetic study of the subfamily Tanypodinae, which includes morphological evidence from modern and fossil chironomids (Silva and Baranov unpub. data), Pentaneurella turned out to be more closely related to the subgenera Reomyia , Schineriella and Zavrelimyia , within Zavrelimyia sensu Silva and Ekrem (2016), than to Trissopelopia , although with low support.

The male of Pentaneurella is morphologically similar to Larsia Fittkau, Pentaneura Philippi, Trissopelopia , and Zavrelimyia Fittkau. The bases of the lyrate tibial spurs are similar to the ones of Larsia and Pentaneura , and the absence of setae on tergite IX resembles Trissopelopia ( Murray and Fittkau 1989). Nonetheless, Pentaneurella differs from Larsia in the presence of a distinctively notched, membranous anal point, while the presence of a distinct scutal tubercle separates adults of Pentaneurella from both Trissopelopia and Pentaneura . Moreover, Pentaneurella appears to be similar to Zavrelimyia sensu lato, only differing from the latter by having a scutal tubercle.

Regarding the immature stages, the pupa of Pentaneurella shows certain similarities to Krenopelopia Fittkau and Monopelopia Fittkau ( Fittkau and Murray 1986). Monopelopia was recovered by Silva and Ekrem (2016) as sister to Nilotanypus Kieffer, and these two taxa as sister to Monopelopia (Cantopelopia) Roback. The presence of a basal lobe and thoracic comb, and anal macrosetae with adhesive sheaths, however, may be used to distinguish Pentaneurella from Krenopelopia and Monopelopia ( Fittkau and Murray 1986). Larvae of Pentaneurella and Krenopelopia differ from Pentaneura and Trissopelopia by possessing a large peg sensilla which is firmly fused with the margin of antennal segment 2, forming a tuning-fork-like process. In both Pentaneurella and Krenopelopia the ligula has a lower middle tooth and inner teeth are curved outward. The absence of a dorsal pore, however, separates Pentaneurella from this genus ( Cranston and Epler 2013). In addition, larvae of Pentaneurella appear to have cephalic setation and fork-like Lauterborn organs similar to those of Zavrelimyia sensu lato.

Remarks on distribution and ecology.

In the Palaearctic, the subfamily Tanypodinae is represented by 29 genera, of which Anatopynia , Johannsen, Telmatopelopia Fittkau and Pentaneurella currently are unique to the region. The latter is a relatively common genus of non-biting midges initially recorded from northern Scandinavia. Currently, the genus has been recorded in Finland ( Paasivirta 2014), France ( Brown et al. 2007, Moubayed-Breil et al. 2012), Germany ( Stur and Wiedenbrug 2006), Norway ( Fittkau and Murray 1983), Russia ( Ashe and O’Connor 2009), Slovakia ( Šporka 2003), Spain ( Hjorth-Andersen 2002), Sweden ( Fittkau and Murray 1983, Bylén and Ronny-Larsson 1994), Switzerland ( Lods-Crozet 1998) and Turkey ( Özkan 2006, Kazanci et al. 2008). Herein, we record Pentaneurella from Central Norway. Several specimens were collected in the Rondane National Park, located in typical high mountain area, with large plateaus and several lentic and lotic systems.

Little is known about the ecology of Pentaneurella . Immature stages seem to be cold stenothermic rheophiles and krenophiles. Larvae of Pentaneurella have been recorded inhabiting springs and spring-fed streams in Sweden and the Bavarian Alps as well as mountain streams in northern and Central Norway ( Fittkau and Murray 1983, Stur and Wiedenbrug 2006, own data). Moubayed-Breil et al. (2012) found Pentaneurella in low and middle mountain streams located in the eastern Pyrenees and Corsica, while Bylén and Ronny-Larsson (1994) recorded larvae of Pentaneurella being parasitized by the microsporidium Pernicivesicula gracilis Bylén & Ronny-Larsson, in a sample of midge larvae collected from a small river in southern Sweden. Furthermore, larvae of Pentaneurella were also recorded from a sand bed stream from insular Turkey ( Özkan 2006).