Dicranophragma (Brachylimnophila) relictum Mederos, 2020

Mederos, Jorge, Gago, Sergi, Brañas, Neus, Fadrique, Floren, Caballero-López, Berta & Masó, Glòria, 2020, A new Dicranophragma (Diptera: Limoniidae) from a hypogeous environment in Catalonia (Iberian Peninsula), European Journal of Taxonomy 724, pp. 109-121 : 113-119

Dicranophragma (Brachylimnophila) relictum Mederos sp. nov.

urn:lsid:zoobank.org:act:06E1B5A9-0618-4121-832E-094B65D3B55A

Figs 1 E–F, 2–3, 4A–D, G, 5A–B, D

Differential diagnosis

General coloration grey to greenish grey, greenish grey hue on thorax in some specimens; dark grey on abdomen. Wings yellowish-brown, veins brown, a little more than four times as long as wide, stigma light brown, poorly defined in some specimens. Petiole of M 1 and M 2 2.5–3 times as long as these veins. Male terminalia in lateral view with acute distal upper part of aedeagus, longer than the lower part. Female terminalia with three spermathecae. Body length 7.0– 11.5 mm, wing length 7.4–10.5 mm. The morphologically closest species is D. nemorale ( Figs 4E, H , 5E ). These two species can be separated by the bi-colored appearance of D. nemorale (light-grey thorax and pale-brown abdomen) compared to the more uniform grey to greenish grey coloration of D. relictum Mederos sp. nov., by the color of the legs (completely yellow in D. nemorale in contrast to the progressively darker brown towards tarsi in D. relictum Mederos sp. nov.), and by the shape of the aedeagus in male terminalia ( Fig. 4 ), in both lateral and dorsal views.

Etymology

The new specific name is a qualifying adjective and a term that comes from the Latin word ‘ relictum ’ that refers to the isolated situation of this species.

Material examined

Holotype

SPAIN • ♂; Catalonia, Barcelona, Sant Llorenç Savall, Parc Natural Sant Llorenç del Munt i l’Obac , Avenc del Daví ; 932 m a.s.l.; 25 Jul. 2019; J. Mederos, S. Gago, F. Fadrique and X. Oller leg.; specimen collected at - 40 m depth; dry specimen, pinned with minute pin on foam; MZB 2019-0985 .

Paratypes

SPAIN • 1 ♂, 2 ♀♀; same collection data as for holotype; dry specimens; MZB 2019-0986 to 2019- 0988 • 1 ♂, 2 ♀♀; same collection data as for holotype; J. Mederos leg.; specimens collected at - 20 m depth; dry specimens; MZB 2019-0989 to 2019-0991 • 3 ♂♂, 1 ♀; same locality as for holotype; 19 Jun. 2019; J. Mederos, S. Gago and F. Fadrique leg.; specimens collected at - 40 m depth; dry specimens; MZB 2019-0944 to 2019-0947 • 1 ♂, 2 ♀♀; same locality as for holotype; 19 Jun. 2019; J. Mederos, S. Gago and F. Fadrique leg., specimens collected at - 40 m depth; in ethanol 70%; MZB 2019-0949 to 2019-0951 • 1 ♂, 1 ♀; same locality as for holotype; 19 Jun. 2019; J. Mederos leg.; specimens collected between -7 to - 27 m depth; in ethanol 70%; RBINS I.G. 34107 • 1 ♂, 1 ♀; same locality as for holotype; 19 Jun. 2019; J. Mederos leg.; specimens collected between -7 to - 27 m depth; in ethanol 70%; MNHN ED10669 , ED10670 • 5 ♀♀; same locality as for holotype; 19 Jun. 2019; J. Mederos leg.; specimens collected between -7 to - 27 m depth; in ethanol 70%; MZB 2019-0954 , MZB 2019-0955 , MZB 2019- 0980 .

Other material examined

SPAIN • 1 ♂, 2 ♀♀; same collection data as for holotype; in absolute ethanol; MZB 2019-0992 to 2019- 0994 .

Description

Male

MEASUREMENTS. Body length (without antennae) 7.0– 7.2 mm. Antenna length 1.3–1.5 mm. Wing length 7.4–8.0 mm.

HEAD ( Fig. 2 ). Grey pruinosity, some specimens with small dark grey dots; small concavity (depression) on vertex, which seems darker in contrast to the surrounding area due to reflection of light. Antenna barely reach fore coxa; scape and pedicel yellow to yellowish brown, pedicel brown in distal half; first flagellomere yellow to yellowish brown, other flagellomeres brown to dark brown towards tip; terminal flagellomere longer than penultimate one; flagellomeres ovoid, narrower and shorter towards tip; verticils about 1.5–2 times as long as their respective flagellomeres.

THORAX ( Fig. 2 ). Grey to greenish grey, occasionally with some brown hues; some specimens have small, dark grey to black dots scattered overall; prescutum with four, dark grey to brownish grey longitudinal stripes, two long central stripes and two other short lateral stripes; in some specimens, the two longitudinal central stripes merge into one broad stripe. Pleura light grey to greenish grey. Coxae and trochanters yellow to yellowish brown. Legs yellowish brown, progressively browner towards tarsi.

WING ( Fig. 3 ). Tinged pale brown to yellowish brown, just over four times as long as wide, veins brown to dark brown, stigma light brown and in some specimens poorly defined. Venation: R 2+3 of variable length, from just longer than R 2+3+4 to more than twice as long; petiole of M 1 and M 2 between 2.5–3 times as long as these veins but in some specimens up to six times this length due to reduction of cell m1 ( Fig. 3H ); cell dm hexagonal, with some variability in shape and length.

ABDOMEN. Grey to greyish brown, covered with short fine silver hairs; apical edge of tergite 7 and tergite 8 dark grey to brown, together with corresponding sternites; tergite 9 yellowish brown, terminalia yellow.

MALE TERMINALIA ( Fig. 4 A–D, G). Gonocoxite conical, less than twice as long as outer gonostylus; outer gonostylus stouter, moderately arched on apical half, paler in two proximal thirds and darker in distal third, with bi-toothed apex. Inner gonostylus fleshy, conical, shorter than outer gonostylus, slightly curved at apex and with several hairs at tip; interbase spoon-like; paramere moderately stout, long and obtuse at apex; aedeagus bipartite distally in lateral view, with upper part acute and longer than lower part.

Female

MEASUREMENTS. Body length 10.5–11.5 mm. Antennae 1.6–1.8 mm. Wing length 9.7–10.5 mm.

As male in general aspect and color, but larger in body size and wingspan. Verticils shorter, about twice as long as their respective flagellomeres. Female terminalia ( Fig. 5 A–B, D) with internal structures as shown in Fig. 5D . Vaginal apodeme (genital fork) short and rather broad. Another prominent feature to consider, in addition to the shape of the vaginal apodeme, is the significant reduction of the inner walls of tergite 9 in the internal structure of the terminalia compared to those of the other species present in the Iberian Peninsula. Spermathecae dark brown, ovoid, the length of the sclerotized parts of their ducts about 2 times as long as the spermatheca ( Fig. 5D ).

Biology

The specimens of D. relictum Mederos sp. nov. reacted little to human contact, either when we were taking photographs just a few centimeters away or when captured. No flight reactions were observed in any specimen of either sex, they only walked on the walls of the chamber or substrate when moving away from their initial resting sites. Only once was a slight wing fluttering observed but without taking flight. An analogous behavior was observed in specimens of the cranefly Tricyphona (Tricyphona) contraria Bergroth, 1888 in another cave with a similar speleogenesis, also in conglomerates and of similar age, in the Montserrat massif, approximately 20 km from Avenc del Daví ( Mederos et al. 2018). The temperature and relative humidity during the study period oscillated between 7.2–9.3ºC and 89.3– 91.8% RH. Venation in craneflies is prone to individual anomalies, including the addition of cross veins and the opening of cells due to vein atrophy ( Edwards 1938; Gelhaus 2009), and we found anomalies in several specimens of this population of D. relictum Mederos sp. nov.

Larvae of Dicranophragma have been reported to be semi-aquatic, being found in springs and beds of fine-grained sediments in large water courses, in marginal situations along flowing and standing waters, in the more or less saturated organic mud of lake margins and marshes, and in rich organic mud near reservoirs ( Reusch & Schrankel 2006; Kramer & Withers 2007; Podenas & Podeniene 2008; Cranston & Drake 2010). Adults have been observed and collected from a variety of habitats including wet mineral and peaty soils, especially wet meadows, small swampy wooded areas, wet scrapes in a field, marshland, a forest above riverbanks, emerging from a forest floor in a beech ( Fagus sp.) forest; with a preference for mildly calcareous soils within wet wooded habitats, and in a semi-wet Fraxinus forest ( Crossley 2003; Boardman 2007, 2016; Nielsen & Nielsen 2009; Starý & Reusch 2009; Drake 2011; Chandler 2015). The absence of the aforementioned ecological conditions in the massif, particularly in the vicinity of the cave, suggests that D. relictum Mederos sp. nov. is isolated in Avenc del Daví and a remnant of a time when the species was found elsewhere in the region when it was characterized by different conditions.

The population of D. relictum Mederos sp. nov. in Avenc del Daví is located approximately from a depth of - 7 m to the chamber located at approximately - 40 m. Several other species of arthropods were observed and sampled in this area, including Limonia nubeculosa Meigen, 1804 ( Diptera : Limoniidae ), the only other cranefly observed in this cave and very abundant during the prospecting dates (June–July 2019). The specimens of L. nubeculosa were distributed uniformly over the walls of the cave, while D. relictum Mederos sp. nov. was found only in specific spaces on the west wall (descent ramp) and on the floor of the chamber located at - 40 m.

Distribution

Species known only from the type locality, Avenc del Daví cave in Catalonia.

Remarks

The examination of the specimens captured in Avenc del Daví reveals differences in structure, both in male terminalia as well as the spermathecae and shape of the inner wall of tergite 9 in female terminalia, that are constant and sufficient to regard this as a distinct from other European species of Dicranophragma . Dicranophragma relictum Mederos sp. nov. can also be distinguished by external characters, such as the body coloration, wing venation and wing pattern. The closest species is D. nemorale , as shown in the differential diagnosis section, widely distributed in the Palearctic and cited in the Iberian Peninsula from Andorra, Portugal and more recently from Spain ( Eiroa 2002; Hancock 2020; Hancock & Hewitt 2020; Oosterbroek 2020).

Figures

Fig. 1. A. General view of the landscape at the approach to Avenc del Daví. B. Cave topography. Indicated in red where Dicranophragma (B.) relictum Mederos sp. nov. was found. C–D. Cave entrance and view from inside. E–F. Female specimen of D. (B.) relictum Mederos sp. nov. (MZB 2019-0951, MCNB) photographed in the cave (E, dorsal view; F, lateral view).

Fig. 4. A–C. Male terminalia of Dicranophragma (B.) relictum Mederos sp. nov. A. Dorsal view. B. Ventral view. C. Lateral view. D–I. Detail of inner and outer gonostylus (dorsal view) and aedeagal complex (lateral view). D, G. D. (B.) relictum Mederos sp. nov. E, H. D. (B.) nemorale (Meigen, 1818). F, I. D. (B.) adjunctum (Walker, 1848). Scale bars = 0.25 mm (images E–F, H–I after Starý & Reusch 2009).

Fig. 5. A–B. Female terminalia of Dicranophragma (B.) relictum Mederos sp. nov. A. Lateral view. B. Dorsal view.C–E. Comparison of the internal structures of female terminalia of threeDicranophragma species (ventral view). C. D. (B.) adjuntum (Walker, 1848). D. D. (B.) relictum Mederos sp. nov. E. D. (B.) nemorale (Meigen, 1818). Abbreviations: see Material and methods. Scale bars = 0.25 mm (images C and E after Starý & Reusch 2009).

Fig. 2. Dicranophragma (B.) relictum Mederos sp. nov., holotype, ♂ (MZB 2019-0985, MNCB). Head and thorax. A. Lateral view. B. Dorsal view. Scale bars = 0.5 mm.

Fig. 3. Dicranophragma (B.) relictum Mederos sp. nov. A. Wing venation. B–H. Variations detected in some specimens such as extra cross veins (C, F–H) and the split at the end of M 3 vein creating a cell (D), as well as variations in the length and shape of cell dm and cell m1 (B, F–H). Scale bar = 1.0 mm.