Planetella granifex ( Kieffer, 1898 )

Ševčík, Jan, Hippa, Heikki, Burdíková, Nikola, Sopuch, Kryštof, Skuhravá, Marcela & Bruun, Hans Henrik, 2023, Integrative taxonomy of Central European Planetella (Diptera: Cecidomyiidae) indicates high species diversity, intraspecific variation and low host specificity, Acta Entomologica Musei Nationalis Pragae 63 (2), pp. 413-450 : 420-424

Planetella granifex ( Kieffer, 1898)

Pseudhormomyia granifex Kieffer 1898: 58 . Type locality: France, Moselle.

Type material. SYNTYPEs: Lost.

Additional material examined. CZECH REPUBLIC: MORAVIA: Polanka nad Odrou, Přemyšov Nature Reserve, v.–vi.2009, 1 J (specimen after DNA extraction, No. PLA 12b, figured in Figs 5C,D ), reared from tussock of Carex acuta, J. Roháček & J. Ševčík leg.; the same locality and collectors, 5.x.2018, 1 larva (specimen after DNA extraction, No. PLA 12) in gall on Carex acuta . Podyjí National Park, Lipinská louka, 26.iv.–20.v.2021, 1 J (specimen after DNA extraction, No. PLA 35), Malaise trap in Carex buekii, J. Roháček & J. Ševčík leg.; the same locality and collectors, 20.v.–25.vi.2021, 1 J (specimen after DNA extraction, No. PLA 41); Poodří Protected Landscape Area, Bernartice, 29.v.–24.vi.2022, 2 JJ (specimens after DNA extraction, No. PLA 53, PLA 53b), emergence trap in C. buekii, J. Ševčík leg. BOHEMIA: Doksy, 15.v.–6.vi.2022, 2 JJ (specimens after DNA extraction, No. PLA 51, PLA 51b), Malaise trap in Carex spp. , M.Tkoč leg. DENMARK: Madesø, 10.viii.2018, 1 larva (specimen after DNA extraction, No. PLA 7) in gall on C. acutiformis ; Hestetang, 1 J (specimen after DNA extraction, No. PLA 50), reared from C. acutiformis ; Klinteskov, 16.iii.2019, 1 J (specimen after DNA extraction, No. PLA 22), reared from C. acutiformis ; SJ, Pamhule Skov, 22.v.2020, 1 ♀ (specimen after DNA extraction, No. PLA 46), reared from C. acutiformis ; SZ: Purlund, 2022, 1 J (specimen after DNA extraction, No. PLA 49), reared from Carex nigra , all H. H. Bruun leg. SLOVAKIA: Cerová vrchovina Protected Landscape Area, Salonkáš, 11.x.2018, 2 larvae (specimens after DNA extraction, No. PLA 14a, PLA 14b) in galls on C. acuta, J. Ševčík leg.; the same locality and collector, 3.iv./ 11.iv.2019, 2 ♀♀ (specimens after DNA extraction, No. PLA 14d, PLA 14e) reared from galls on C. acuta , one of them in Fig. 2 ; Cerová vrchovina Protected Landscape Area, Tachty, meadow, 21.v.–19.vi.2019, 2 JJ (specimens after DNA extraction, No. PLA 18a, PLA 18b), Malaise trap in C. acutiformis, J. Roháček & J. Ševčík leg.; the same locality and collectors, 28.viii.–25.ix.2019, 1 J (specimen after DNA extraction, No. PLA 28a); the same locality and collectors, 12.v.–11.vi.2021, 1 J (specimen after DNA extraction, No. PLA 38); the same locality and collectors, 20.viii.–16.ix.2021, 1J (specimen after DNA extraction, No. PLA 44); Muránska planina National Park, Trsteník valley, 10.vi.–13.vii.2021, 1 J 1 ♀ (specimens after DNA extraction, No. PLA 42c, PLA 42d), 13.vii.–19.viii.2021, 1 J (specimen after DNA extraction, No. PLA 42), emergence trap over C. rostrata, J. Roháček & J. Ševčík leg.; Tisovec, Trstie Nature Reserve, 12.vii.–16.viii.2023, 1 J (specimen after DNA extraction, No. PLA 71), Malaise trap in C. rostrata, J. Roháček & J. Ševčík leg. (all specimens in JSL-UOL collection).

Diagnosis. This species can be easily recognized by the shape of gonostylus, which is ovoid, with a small apical tooth, in combination with apically excavated subrectangular hypoproct, aedeagus much shorter than hypoproct, and broad gonocoxite ( Figs 5C,D ). Female has distinctly prolonged abdomen posteriorly ( Fig. 1B ). It belongs to the group with 12 flagellomeres, narrow eye bridge, and uniform, mostly light orange-brown coloration.

Variation. According to DNA sequences, two distinct forms can be distinguished. The more common one, which we consider as true P. granifex (specimens listed above), and the second one, differing 3 % in COI barcode sequence, known only from the following three localities:

SLOVAKIA: Muránska planina National park,Rosiarka Nature Reserve, 21.vi.–18.vii.2022, 1 J (No. PLA 59, specimen after DNA extraction), J. Roháček & J. Ševčík leg., Malaise trap in C. rostrata ; the same data except Trstie Nature Reserve, 12.vii.–16.viii.2023, 1♀ ( PLA 72, specimen after DNA extraction); POLAND: Białowieża Forest, 23.viii.2018, 1 larva ( PLA 9, specimen after DNA extraction), H. H. Bruun leg., in gall on Carex acuta (all specimens in JSL-UOL collection).

The second form could be considered as a separate species, although we have not found yet any notable difference in the structure of the male terminalia, nor in any other morphological character. If we take into account that Planetella populations are very local (due to specific habitats used) and not much mobile (robust females probably only crawl, not fly), thus preventing gene flow and promoting speciation, we prefer to consider such populations as separate cryptic species. The other possibility would be that this is a mere infraspecific variation and gene flow still exists.

In insect molecular studies, species delimitation is usually based on 2 to 4% threshold (difference) in COI barcode sequence, depending on methodology and taxonomic group (e.g. HEBERT et al. 2003a,b, MEIER et al. 2006, RENAUD et al. 2012, KONDO et al 2016, CHAIPHONGPACHARA et al. 2022, KJAERANDsEN 2022, SRIVATHsAN et al. 2023). YUKAWA et al. (2019) reported for Japanese Asphondylia ( Cecidomyiidae ) only 2% divergence among the species. As stated already by MEIER et al. (2006), threshold value for distinguishing intra- from interspecific distances is largely arbitrary and renders species borders a matter of opinion. In any case, we leave the second form of granifex as unnamed until more material is collected.

Discussion. KIEFFER (1898) described this species in the monotypic genus Pseudhormomyia Kieffer, 1898 , on the basis of several general characters on habitus, including prolonged ovipositor and three palpomeres in female. No figures of this species were provided in the original description. Figures of the male terminalia, female habitus and larva were included in his later work ( KIEFFER 1913). Most of Kieffer’s types can be considered as almost certainly lost, including this one (GAGNḖ & JAsCHHOF 2021). Our interpretation of this species is based on the study of material identified as P. granifex in the collection of Rübsaamen in Berlin, as well as on the figures of the male terminalia in KIEFFER (1913) and SKUHRAVÁ (1997).

Based on the original figures in RȖBsAAMEN (1911 h), Planetella caricis ( Rübsaamen, 1911) could be considered conspecific with this species and thus represent a junior synonym of P. granifex . However, we have seen several specimens identified as P. caricis in the Rübsaamen collection in Berlin, and they most probably represent a different species. Similarity of the galls caused and the range of Carex species used as host plants may have caused the confusion.

According to the original description and subsequent figure of the male terminalia in KIEFFER (1913), P. subterranea should be a very similar species or even identical with granifex .

Biology and distribution. This species currently appears to be the most common and widely distributed Planetella in Central Europe, associated mainly with larger sedges ( Carex acuta , C. acutiformis . C. buekii , C. rostrata ), without apparent specificity to a particular host. At the same time, several other species of Planetella are associated with Carex acuta , C. acutiformis and C. rostrata . Kieffer (1898) in his original description mentions three host species, Carex stellulata (= C. echinata ), C. pallescens and C. stricta (= C. elata ). P. granifex also remains one of the few Planetella species, where galls ( Fig. 1C ) are regularly found and well documented.

Figures

Fig. 5. Male terminalia in ventral (A, C) and dorsal (B, D) view.A, B – Planetella gallarum (Rübsaamen, 1899) (Denmark, specimen PLA6a). C, D – P. granifex (Kieffer, 1898) (Czech Republic, specimen PLA12b). Scale 0.1 mm.

Fig. 2. Galls of Planetella species.A – Planetella gallarum (Rübsaamen, 1899) on Carex nigra var. recta (Denmark, Ejstrup, 9.vi.2016, photo by H.-H. Bruun). B – Planetella sp. B on Carex hirta (Slovakia, Cerová vrchovina, Salonkáš, 11.x.2018, photo by J. Ševčík). C–E – Planetella granifex (Kieffer, 1898) on Carex acuta (Slovakia, Cerová vrchovina, Salonkáš, 11.x.2018, photos by J. Ševčík).

Fig. 1. Adults of Planetella species. A – male of Planetella submontana Ševčík & Hippa sp. nov. collected when sitting on a Malaise trap (Slovakia, Muránska planina, Trsteník, 16.vi.–14.vii.2016). B – female of Planetella granifex (Kieffer, 1898) reared from gall on Carex acuta (Slovakia, Cerová vrchovina, Salonkáš, 3.iv.–11.iv.2019). All photos by J. Ševčík.