Chaetocladius callauensis, Moubayed & Langton, 2019

Moubayed, Joel & Langton, Peter H, 2019, CHAETOCLADIUS BERYTHENSIS SP. N., C. CALLAUENSIS SP. N., C. GUARDIOLEI SP. N. AND C. PARERAI SP. N., FOUR RELICT SPECIES INHABITING GLACIAL SPRINGS AND STREAMS IN EASTERN PYRENEES AND LEBANON (DIPTERA: CHIRONOMIDAE) Abstract, CHIRONOMUS Journal of Chironomidae Research 32 (32), pp. 42-59 : 44-47

Chaetocladius callauensis sp. n.

http://zoobank.org/ 8A3665D5-6D2A-461E-AC81- AC15EFAA376C

Material examined. Holotype. 1 male adult, France, eastern Pyrenees , Mantet Nature Reserve , upper basin of the River Mantet , Ressec glacial stream, Callau acid helocrenes springs and peat bogs, 42° 28’ 38’’ N, 02° 18’ 26’’ E, altitude 2000- 2300 m a.s.l., 05.VIII.2010, leg. J. Moubayed. Water crystalline, conductivity 30-40 µS/cm, pH 5.5- 5.7; temperature 8-10 °C, during summer, about 3-5 °C in winter and spring.

Paratypes. 3 tentatively associated pupal exuviae (2 males and 1 female), same locality and date as for holotype; 1 male adult, 2 tentatively associated male pupal exuviae, Font des Soques glacial spring and stream at Mantet Nature Reserve. 1 male adult and 1 male pharate adult, alt. 2000- 2100 m, 05.08.2010, leg. J. Moubayed-Breil. Water crystalline, conductivity 20-30 µS/cm, pH 5.5- 5.7; temperature 8-10 °C during summer period.

Holotype (male adult mounted on 1 slide) is deposited in the collections of the National Museum of Ireland, Kildare Street , Dublin 2, Ireland . Paratypes are deposited in the senior author’s collection.

Etymology. The new species is named ‘ callauensis ’ after the protected glacial helocrene springs and peat bogs area of Mantet Nature Reserve, which is located at high altitude (2000-2300 m) in the Eastern Pyrenees (SW-France) where the type material was collected.

Diagnostic characters

Based on the atypical shape of the inferior volsella C. callauensis sp. n. appears to belong to a separate group within the genus Chaetocladius . However, this new species is also distinguished from other known Chaetocladius species in having: semi-circular clypeus with 2 distal margins; lobes of antepronotum not gaping, distinctly thinner and parallel-sided medially; humeral pit ellipsoidal, surrounded by dense contrasting brownish granulation; tergite IX without dorsal hump; virga weakly-developed, consisting of 2 sinuous fine spines; gonocoxite rounded apically, ventral margin with 2 broad lobes; inferior volsella composed of 2 sub-equal parts, proximal one rectangular, consisting of a contrasting smooth lobe which is hyaline and bare, distal one rounded and densely covered with setae; gonostylus slender, thinner proximally, bulbous and thicker in its distal half, posterior margin rounded; crista dorsalis wide, lower proximally, becoming higher and more conspicuous close to the megaseta.

Description

Male adult

(n = 3; Figs 2 D-G, 3A-G)

Large. Total length 3.90-4.00 mm. Wing length 2.70-2.75 mm; TL/WL 1.07. General colouration brown to dark brown. Head and antennae brown; thorax contrasting brown to dark brown, mesonotal stripes distinctly dark brown, humeral pit brownish with contrasting granulation; wing pale; legs brown; tergites I-VIII brownish, anal segment brown to dark brown.

Head. Eyes bare between ommatidia, hairs absent on inner lateral eye margin, a few short setae present on outer posterior margin. Temporals consist of 11 setae including 9 inner and 2 outer verticals; palpomere 3 ( Fig. 2D ) with 3 sensilla clavata and 4 sensilla coeloconica; clypeus ( Fig. 2E ) 115 µm long, and 210 µm maximum width, semi-circular, bearing 18 setae in 4-5 rows. Antenna 1100 µm long; last flagellomere 565 µm long, clubbed distally, covered with a dense brush of curved sensilla chaetica apically, pre-apical seta absent; antennal groove beginning on segment 2 and reaching ultimate flagellomere; AR 1.06. Thorax. Anteprontum ( Fig. 2F ), lobes weakly-developed at base and not gaping, distinctly thinner and parallel-sided medially, with 6 lateral antepronotals; acrostichals 16- 17; dorsocentrals 12-13; prealars 4-5; humeral pit ( Fig. 2G ) ellipsoid, surrounded by dense contrasting granulation. Wing. Brachiolum with 1 seta; membrane densely covered with coarse punctuation; number of setae on veins: R, 7; R 1, 10; remaining veins bare; squama with 19-23 setae in 1 row. Legs. Tibial spur of PI spiniform. Length (µm) of tibial spurs of: PI, 65; PII, 35 and 20; PIII, 70 and 30; longest seta of tibial comb 50 µm long. Sensilla chaetica few (proximally and distally) on tibia and tarsomeres ta 1 -ta 5 of PI-PIII. Length (µm) and proportions of prothoracic (PI), mesothoracic (PII) and metathoracic (PIII) legs as in Table 2 .

Hypopygium as in dorsal ( Fig. 3A ) and lateral view ( Fig. 3F ), ventral view with tergite IX and anal point omitted as in Fig. 3 B . Tergite IX broadly semi-circular, wider at base and narrowing posteriorly up to its 1/4 th distal part; dorsal setae 26-28 include 10-12 located above the base of anal point and 14-16 close to the posterior margin (located in in 2 curved rows and placed on each side of the base of anal point); dorsal hump absent ( Fig. 3G ). Anal point in dorsal ( Figs 3A, C ) and lateral view ( Fig. 3G ) 75 µm long, about 135 µm maximum width at base, markedly wider at base, parallel-sided in its distal part and rounded apically, bare and hyaline part about 25 µm long; 8-9 setae are present both dorsally and laterally. Latero-sternite IX with 11 setae inserted laterally (5-6 on each side). Sternapodeme and phallapodeme ( Fig. 3B ), phallapodeme distinctly wider anteriorly. Virga ( Fig. 3A ) weakly-developed, consists of 2 sinuous spines about 25 µm long. Gonocoxite ( Figs 3 A-B, F) 300-330 µm long and 125 µm maximum width, rounded apically, ventral margin bi-lobed, with 10 stout setae; inferior volsella in dorsal ( Fig. 3A ) and lateral view ( Fig. 3F ) well-developed, composed of 2 sub-equal lobes, proximal one rectangular and contrasting, smooth on its inner part which is hyaline and bare, distal lobe densely covered with short setae. Gonostylus at acute angle ( Fig. 3D ) and at right angle ( Fig. 3E ) 155 µm long and 40 µm maximum width, slender, thinner proximally, becoming bulbous and thicker in its distal half, posterior margin rounded; megaseta about 12 µm long; crista dorsalis extending from proximal part of gonostylus to the megaseta, a wide lobe proximally, becoming higher and more conspicuous in its distal half close to the megaseta.

Figures

Figure 2. Male adult of Chaetocladius spp. C. berythensis sp. n.: A) anal point, dorsal; B) gonostylus, ventral; C) gonostylus, lateral. C. callauensis sp. n.: D) palpomere 3; E) clypeus; F) lobes of antepronotum; G) humeral pit.

Figure 3. Male adult of Chaetocladius callauensis sp. n.A) hypopygium, dorsal; B) hypopygium, ventral; C) anal point, dorsal; D) gonostylus, acute angle; E) gonostylus, obtuse angle; F) gonocoxite and inferior volsella, lateral; G) anal point and tergite IX in lateral view.