Philopterus acrocephalus Carriker, 1949

Najer, Tomas, Papousek, Ivo, Adam, Costica, Trnka, Alfred, Quach, Van Thi, Nguyen, Chinh Ngoc, Figura, Roman, Literak, Ivan & Sychra, Oldrich, 2020, New records of Philopterus (Ischnocera: Philopteridae) from Acrocephalidae and Locustellidae, with description of one new species from Regulidae, European Journal of Taxonomy 632, pp. 1-37 : 8-16

Philopterus acrocephalus Carriker, 1949

Figs 1–5 , 8 A–B; Tables 2–5

Material examined

Holotype

USA • ♀ ( Fig. 1 ); Marianas , Guam Island; 4 Jun. 1945; R.H. Baker leg.; ex Acrocephalus luscinius luscinius; USNM No. 58960.

Other material

SLOVAKIA • 1 ♂, 1 ♀; Nitra Region , Nove Zamky District, Gbelce; 47°52′N, 18°30′E; 19 Apr. 2009; T. Najer & O. Sychra leg.; ex Acrocephalus melanopogon; MMBC SK21 • 1 ♂, 1 ♀; same collection data as for preceding; MMBC SK22 • 1 ♂, 1 ♀; same collection data as for preceding; MMBC SK23 • 1 ♂, 1 ♀; same collection data as for preceding; MMBC SK24 • 1 ♂ ( Fig. 8A ), 1 ♀ ( Fig. 8B ); same collection data as for preceding; MMBC SK25 .

ROMANIA • 1 ♀; Tulcea County, Letea ; 45°20′N, 29°32′E; 9 Apr. 2011; C. Adam leg.; same host as for preceding; MGAB ISC 317 • 1 ♀; same collection data as for preceding; MGAB ISC 318 • 1 ♀; same collection data as for preceding; MGAB ISC 319 • 1 ♂; same collection data as for preceding; MGAB ISC 320 • 1 ♂; same collection data as for preceding; MGAB ISC 321 • 1 ♂; same collection data as for preceding; MGAB ISC 322 .

AZERBAIJAN • 3 ♂♂, 2 ♀♀; 18 Apr. 1937; A. Ivanov leg.; same host as for preceding; ZIN • 1 ♂, 4 ♀♀; 24 Apr. 1937; same collector and host as for preceding; ZIN .

RUSSIA • 1 ♂, 1 ♀; Korsakovo ; 3 Aug. 1947; Lyubin leg., same host as for preceding; ZIN I 65 • 1 ♂, 1 ♀; Astrakhan Oblast, Astrakhan State Nature Reserve ; 9 Aug. 1946; ex Acrocephalus schoenobaenus; ZIN I-8 • 1 ♀; same collection data as for preceding; 14 Aug. 1946; ZIN I 12/7 • 1 ♂; Amur Oblast, Tambovka on Amur District ; 26 Jul. 1939; D.I. Blagoveshtchensky leg.; ex Iduna aedon rufescens ; ZIN I216 • 2 ♀♀, 3 ʘʘ; same collection data as for preceding; 29 Jul. 1939; ZIN I277 • 1 ♀, 1 ʘ; same collection data as for preceding; 3 Aug. 1939; ZIN I341 .

AUSTRIA • 1 subad. ♀; Burgenland, Neusiedl am See ; 18 Sep. 1960; F. Balat leg.; ex Acrocephalus melanopogon; MMBC No. 1229 .

TAJIKISTAN • 4 ♀♀; Khatlon Region, Qurgonteppa ; 29 May 1932; ex Iduna rama ; ZIN I250/353 • 2 ♀♀; Districts of Republican Subordination, Gissar Range ; 23 Apr. 1934; ex Locustella sp.; ZIN A-129 .

COUNTRY UNKNOWN • 1 ♂; 8 May 1909; A. Derzhavin leg.; ex Locustella ochotensis ; ZIN.

Additional collected material

SLOVAKIA • 18 ♂♂, 21 ♀♀, 27 ʘʘ; Nitra Region , Nove Zamky District, Gbelce; 47°52′N, 18°30′E; 12 Apr.–3 May 2008; I. Literak, M. Capek & O. Sychra leg.; ex Acrocephalus melanopogon; UVPS • 12 ♂♂, 6 ♀♀, 18 ʘʘ; same collection data and host as for preceding; 18 Apr.–1 May 2009; T. Najer, I. Literak, M. Capek & O. Sychra leg.; UVPS • 11 ♂♂, 20 ♀♀, 16 ʘʘ; same collection data and host as for preceding; 18–21 Apr. 2016; T. Najer, T. Judak, L. Oslejskova & O. Sychra leg.; UVPS .

GREECE • 1 ♂, 1 ♀, 1 ʘ; Pieria, Central Macedonia Region, Nea Agathoupoli ; 40°27′N, 22°34′E; 14 Dec. 2013; A. Diakou leg.; same host as for preceding; UVPS .

Not determinable material

In addition to the examined material of Ph. acrocephalus , we examined the following specimens. They were noticeably different from Ph. acrocephalus but could not be determined because of a lack of available material of other species for comparison.

CZECHIA • 6 ʘʘ; Highlands Region, Jihlava District, Jihlava ; 25 Aug. 1958; F. Balat leg.; ex Acrocephalus scirpaceus; MMBC No. 1387 .

POLAND • 3 ʘʘ; Warmian-Masurian Voivodeship, Braniewo County, Pasleka ; 19 Aug. 1963; Busse leg.; ex Acrocephalus palustris; labeled as Docophorulus mirificus ; MNHW 8/i/4–6 .

EGYPT • 1 ♀; Bahiq ; 7 Oct. 1966; ex Acrocephalus schoenobaenus; labeled as Philopterus necopinatus ; USNM .

AUSTRIA • 1 subad. ♂; Burgenland, Neusiedl am See ; 17 Sep. 1960; F. Balat leg.; ex Acrocephalus scirpaceus; MMBC No. 1232 .

COUNTRY UNKNOWN • 1 ♂, 2 ʘʘ; 25 May 1931; ex Iduna aedon ; ZIN 1463.

Description

Both sexes

Head as in Fig. 4C , slightly longer than wide, with frons slightly concave, preantennal region with slightly concave lateral margin approximately the same length as the postantennal margin. Hyaline margin enlarged, wider than frons. Dorsal anterior preantennal plate (ADP) as in Fig. 4B , with slightly centrally indented anterior margin and straight or slightly concave anterior part of lateral margin. Posterolateral margin of ADP straight or slightly concave, but not sclerotized and therefore almost not apparent, the sclerotization of ADP forming 1 wide, large central and 2 small lateral triangular projections with straight margin, the indentations between the central and lateral projections about the same size as the lateral projections, sharply angled ( Fig. 4B ). Ventral anterior plate as in Fig. 4C , with lateral and posterior margins continuously merging into 1 rounded postero-lateral margin. Prothorax as in Fig. 4A, E , with 1 long postero-lateral pps on each side and 3 short thorn-like setae on each side of its anterior margin. Prosternum narrow and elongated, mesosternum rhombic. In place of metasternum 2 medium-long setae on each side. Pterothorax with 5–6 long setae (pths) on each side. Pterothorax with lateral margins straight, reaching approximately to the same level as spiracles on segment II. Tergopleurites II–IX all with long most lateral seta, tergocentral setae (tcs) generally very long, mostly overreaching length of 3 abdominal segments, sutural setae (ss) medium-long, about the length of 2 abdominal segments. Leg chaetotaxy as in Fig. 5 , measurements as in Table 3.

Male

Habitus as in Fig. 4A , head as in Fig. 4C . Lateral parts of pterothorax with 4 separate setae (ptls) on each side, 1 medium-long (1 st, counting from the most lateral), 2 short (2 nd– 3 rd) and 1 long (4 th). Thoracic and abdominal chaetotaxy as in Fig. 4A and Table 2. Sternal setae (sts) on segments II–III short, on segments IV–VI medium long, shorter or approximately the same length as ss. Subgenital plate of rectangular shape, as in Fig. 4A , with rounded anterior margin, with only slight indentations on both lateral sides. Posterior margin of central part of subgenital plate not clear, 2 (median long and lateral medium-long) setae at the level of anterior lateral indentation and 1 medium-long seta at the level of posterior lateral indentation on each side. Genitalia as in Fig. 4D , basal apodeme long and quadrangular, lateral margins concave, anterior margin rounded. Parameres elongated, length about ½ of width of basal plate, overreaching the mesosome, kidney-shaped, clearly separated from the basal plate, with 2 sensillae on each side of posterior margin. Mesosome consisting of 2 fingerlike parts, which are parallel to each other, proximally fused with basal plate, with bulbous distal part and bluntly pointed posteromedian end.

Female

Habitus as in Fig. 4E . Lateral part of pterothorax with 3 separate setae (ptls), 1 st and 3 rd counting from the most lateral medium-long, the 2 nd short. Thoracic and abdominal chaetotaxy as in Fig. 4E and Table 2. Sternal setae (sts) on segment II short, on the other segments medium-long, on segments III–IV shorter, on segments V–VI about the same length as ss, the most median VI sts longer than the others. Subgenital plate ( Fig. 4F ) with rounded anterior margin, concave posteriolateral margins and rounded central part of posterior margin. Posterio-lateral parts of subgenital plate separated as vestigial sternites VIII ( Fig. 4F ). Two long lateral setae on each side, 1 in area of original sternite VII, 1 behind the posterior margin of lateral sternite VII. Subvulval sclerites, associated chaetotaxy and vulval margin as in Fig. 4F . Inner genital sclerites missing, the area where the vulval margin is visible in other Philopterus species with a row of 7 short slender setae on each side.

Hosts

Type host

Acrocephalus luscinius (Quoy & Gaimard, 1830).

Other hosts

Acrocephalus melanopogon (Temminck, 1823), Acrocephalus scirpaceus (Hermann, 1804), Acrocephalus schoenobaenus (Linnaeus, 1758) – from these three hosts, some Philopterus species are described, but it is not definitely confirmed that they are synonyms of Ph. acrocephalus . Therefore, we cannot exclude that material examined by us represents new host records. Iduna aedon rufescens Stegmann, 1929 – new host record, Iduna rama (Sykes, 1832) – new host record, Locustella sp. – new host record, Locustella ochotensis (von Middendorff, 1853) – new host record.

Distribution

Type locality

USA, Guam Island.

Other published locations

Czechia (Balat in Hudec 1983); Hungary ( Vas et al. 2012a); Greece, Nea Agathoupoli ( Diakou et al. 2017). Always mentioned as Philopterus sp. ex A. melanopogon, considered to be Ph. acrocephalus according to host association.

Newly reported locations

Slovakia, Gbelce; Romania, Letea; Greece, Nea Agathoupoli; Azebaijan without further specification; Russia, Astrakhan State Nature Reserve; Russia, Korsakov; Russia, Tambovka in Amur District; Tajikistan, Gissar Range; Tajikistan, Qurgonteppa; Austria, Neusiedl am See.

Remarks

Because the holotype is rather old and not all its morphological features are clearly visible, were used specimens of A. melanopogon collected in Slovakia for the drawings. The genitalia of the male used to draw all male figures differ in appearance from the other examined males due to the slide-mounting process. The mesosome of these male genitalia is bent upwards, so the shape is not clearly visible. For this reason, for the figure of the male genitalia, we used the mesosome of another specimen, the genitalia of which are otherwise the same as those of the mainly drawn specimen. Specimens of Ph. acrocephalus from Azerbaijan have a relatively more narrow central posterior projection of the ADP; in other ways, the morphological features are the same as in the other examined material. In general, the relative size of lateral and posterior ADP projections shows the largest variability of all the morphological characteristics.

Genetic diversity

Two specimens of Ph. acrocephalus from Acrocephalus melanopogon were genetically analysed, in which all three examined genes (mitochondrial COI, nuclear hyp and TMEDE6) amplified. Since both examined specimens were from the same host species, their sequences also showed 100% identity in all three genes and the concatenated sequences as well ( Table 4). The three other species for genetic comparison, Ph. gustafssoni sp. nov. (net interspecific p -distances 23.1% for COI, 1.6% for hyp, 0.8% for TMEDE6 and 9.7% for the concatenated sequences), Ph. fringillae (24.5% for COI, 1.8% for hyp, 1.4% for TMEDE6 and 10.5% for the concatenated sequences) and Ph. citrinellae (19.8% for COI, 1.8% for hyp, 1.2% for TMEDE6 and 8.6% for the concatenated sequences) were chosen because their net interspecific p -distances from Ph. acrocephalus were the shortest from all by us sequenced Philopterus samples (Najer, unpublished results). More details about these distances are given in Table 5.

Figures

Fig. 1. Philopterus acrocephalus Carriker, 1949 ex Acrocephalus luscinius: female holotype (USNM No. 58960), dorsal view. Scale bar: 0.1 mm.

Fig. 2. Philopterus acrocephalus Carriker, 1949 ex Acrocephalus melanopogon (SK25 in MMBC): points of measurements and nomenclature of sclerites and setae. A. Male genitalia, ventral view. B. Male dorsal preantennal plate (ADP), dorsal view. C. Female subgenital plate and ventral terminalia, ventral view. D. Male head, dorsal and ventral views. Abbreviations: sclerites: sgp – subgenital plate; svs – subvulvar sclerite; vs VIII – vestigial sternite VIII; setae: ads – anterior dorsal seta; as – anterior seta; avs – anterior ventral seta; dsms – dorsal submarginal seta; mds – mandibular seta; ms – mental seta; mts – marginal temporal seta; os – ocular seta; pas – preantennal seta; pcs – preconal seta; pos – postocular seta; pns – postnodal seta; pts – postemporal seta; s – sensillus; vsms – ventral submarginal seta. Measurements: ADPL – anterior dorsal plate length; APLL – anterior dorsal plate lateral length; ADPW – anterior dorsal plate width; ANW – anterior notch width; GL – male genitalia length; GW – male genitalia width; HL – head length; PAL – preantennal length; PAW – preantennal width; PMCL – premarginal carina length; POL – postantennal length; TRL – trabecula length; TRW – trabecula width; TW – temporal width; SGPW – subgenital plate width. Scale bars: 0.1 mm.

Fig. 3. Philopterus acrocephalus Carriker, 1949 ex Acrocephalus melanopogon (SK25 in MMBC): female habitus showing points of measurements and nomenclature of abdominal setae, dorsal and ventral views. Abbreviations: setae: ats – anterior tergal seta; ps – paratergal seta; pps – pronotal postspiracular seta; pths – pterothoracic seta; ptls – pterothoracic lateral seta; ss – sutural seta; sts – sternal seta; tcs – tergocentral seta. Measurements: AL – length of abdomen; AW – maximal width of abdomen; HL – head length; PTL – pterothorax length; PW – prothorax width; PTW – pterothorax width; TL – total length; TPVL – tergal plate V length. Scale bars: 0.1 mm.

Fig. 4. Philopterus acrocephalus Carriker, 1949 ex Acrocephalus melanopogon (SK25 in MMBC). A. Male habitus, dorsal and ventral views. B. Male dorsal anterior plate (ADP), dorsal view. C. Male head, dorsal and ventral views. D. Male genitalia, ventral view. E. Female habitus, dorsal and ventral views. F. Female subgenital plate, vulval margin and ventral terminalia, ventral view. Scale bars: 0.1 mm.

Fig. 5. Philopterus acrocephalus Carriker, 1949 ex Acrocephalus melanopogon (SK25 in MMBC): nomenclature of male leg chaetotaxy, dorsal and ventral views. Abbreviations: c – coxa; t – trochanter; f – femur; dm – distal marginal seta; d – dorsal seta; a – anterior seta; p – posterior seta; s – sensillus; v – ventral seta. Scale bar: 0.1 mm.

Fig. 8. A–B. Philopterus acrocephalus Carriker, 1949 ex Acrocephalus melanopogon: A. Herein described and illustrated male (MMBC SK25), dorsal view. B. Herein described and illustrated female (MMBC SK25), dorsal view. – C–D. Philopterus gustafssoni sp. nov. ex Regulus regulus: C. Holotype (MMBC CZ-OS01), dorsal view. D. Herein described and illustrated female paratype (MMBC CZ-OS01), dorsal view. Scale bars: 0.1 mm.