Myrsidea aegithali ( Blagoveshtchensky, 1940 )

Schneider, Marek, Kolencik, Stanislav, Literak, Ivan & Sychra, Oldrich, 2025, Redescriptions of three species in the louse genus Myrsidea (Insecta: Phthiraptera: Amblycera), Zootaxa 5653 (3), pp. 411-428 : 413-417

Myrsidea aegithali ( Blagoveshtchensky, 1940)

( Figs 1–6 , 20–24 )

Myrsidea aegithali Blagoveshtchensky, 1940: 39 , fig. 11.

Myrsidea aegithali Blagoveshtchensky, 1940 ; Price e t al. 2003: 127.

Type host: Aegithalos caudatus alpinus (Hablizl, 1783) ( Passeriformes , Aegithalidae )—Northern long-tailed tit.

Type locality: Azerbaijan. Alekseevka (former name of Dashtatiuk village ) and Kumbashi, Lankaran Region (Алексеевка, Kуmбaши, Ленкоранский район).

Diagnosis

Myrsidea aegithali is distinctly characterized by its male genital sac sclerite, which is unique within the genus Myrsidea . The sclerite is large, with a broadly rounded distal margin and densely fringed patches on the lateral sides ( Figs 3–4 ). Hence, Kolencik et al. (2024: 38) established the aegithali morphotype-group for this species. Females are diagnosed by the following combination of characters: hypopharyngeal sclerites weakly developed ( Fig. 23 ); abdominal segments with well-defined median gap in each row of tergal setae, and slightly modified tergites. II–III ( Figs 1 , 5 ). Nevertheless, a detailed description of females of similar species is necessary for a reliable differentiation.

Descriptions

Female (n = 14). As in Figs 1 , 5 , 20, 23 . Some data from the lectotype female ( Figs 20, 22 ) are given in square brackets. Hypopharyngeal sclerites weakly developed ( Fig. 23 ). Length of dhs 10, 0.04–0.05 [0.04]; dhs 11, 0.09– 0.11 [0.09]; ratio dhs 10/11, 0.42–0.50 [0.44]. Ls5 0.02–0.06 long, latero-ventral fringe with 9–10 [10] setae. Gula with 5–7 [5–6] setae on each side. Pronotum with 6 (5 in one case) [6] setae on posterior margin and 3 [3] short spiniform setae at each lateral corner. Prosternal plate with rounded anterior margin. First tibia with 3 [3] outer ventro-lateral and 3 [3] dorso-lateral setae. Mesonotum undivided. Metanotum not enlarged, with 6–8 [8] marginal setae (the most posterolateral setae are not included); metasternal plate with 6 [6] setae; metapleurites with 2–3 [3] short strong spiniform setae. Femur III with 13–16 [14–15] setae in ventral setal brush.

Tergites not enlarged, with straight posterior margin, only tergites II–III with slightly convex margin ( Figs 1 and 5 ). Abdominal segments with well-defined median gap in each row of tergal setae. Tergal setae (postspiracular setae and short associated setae on tergites II–VIII are not included): I, 9–12 [9]; II, 8–15 [13]; III, 11–14 [14]; IV, 10–13 [11]; V, 8–12 [16]; VI, 8–13 [9]; VII, 8–11 [11]; VIII, 5–9 [7]. Postspiracular setae very long on tergites II, IV and VIII (0.30–0.38) [0.31–0.34]; long on I, III and VII (0.18–0.29) [0.21–0.26]; and short on V and VI (0.11–0.18) [0.11–0.15]. Inner posterior seta of last tergum not longer than anal fringe setae with length 0.07–0.10 [0.07–0.08]; length of short lateral marginal seta of last segment, 0.04–0.06 [0.04]. Pleural setae: I, 4–6 [5]; II, 5–7 [5]; III, 4–7 [4–5]; IV, 5–6 [5–6]; V, 4–5 [4–5]; VI, 3–4 [4]; VII, 3 [3]; VIII, 3 [3]. Pleurites I–III with only short spine-like setae; with slender and longer setae on: IV, 1–2; V, 1–3; VI, 1–4; VII, 1–2; without anterior setae. Pleurite VIII with inner setae (0.06–0.10) twice as long as outer (0.02–0.05). Anterior margin of sternal plate II without a medial notch. Sternal setae: I, 0 [0]; II, 4 (in one case 5) [4] in each aster ( Fig. 2 ), aster setae length: s1, 0.05–0.06; s2, 0.04–0.05; s3, 0.03–0.04; s4, 0.02–0.03, s5, 0.02–0.03; with 12–14 [13] marginal setae between asters, 3–5 [4] medioanterior; III, 17–25 [23]; IV, 25–35 [32]; V, 31–36 [31]; VI, 26–35 [28]; VII, 16–22 [16]; VIII–IX, 19–26; and 8–13 [10] setae on slightly serrated or almost smooth vulval margin; sternites III–VII with medioanterior setae: III, 1–2; IV, 2–3; V, 2–3; VI, 2–3; VII, 2. Anal fringe formed by 28–33 [30] dorsal and 28–35 [33] ventral setae.

Dimensions (ex Aegithalos caudatus ): TW, 0.42–0.44 [0.42]; POW, 0.33–0.35 [0.33]; HL, 0.24–0.27 [0.24]; PW, 0.28–0.30 [0.29]; MW, 0.41–0.46 [0.42]; AWIV, 0.68–0.70 [0.67]; ANW, 0.17–0.20 [0.18]; TL, 1.48–1.59 [1.53]. Dimensions (ex Aegithalos concinnus ): TW, 0.38–0.39; POW, 0.31; HL, 0.25–0.26; PW, 0.25–0.26; MW, 0.38–0.40; AWIV, 0.56–0.61; ANW, 0.18; TL, 1.31–1.35.

Male (n = 9). As in Figs 6 , 2 , 24 , Hypopharyngeal sclerites weakly developed. Length of dhs 10, 0.04; dhs 11, 0.08–0.09; ratio dhs 10/11, 0.44–0.50. Ls5 0.05–0.07 long, latero-ventral fringe with 9–11 setae. Gula with 5–6 setae on each side. Pronotum with 6 setae on posterior margin and 3 short spiniform setae at each lateral corner. Prosternal plate with rounded anterior margin. First tibia with 3 outer ventro-lateral and 3 dorso-lateral setae. Mesonotum undivided. Metanotum not enlarged with 3–5 marginal setae (the most posterolateral setae are not included); metasternal plate with 5–6 setae; metapleurites with 2–3 short spiniform strong setae. Femur III with 10–15 setae in ventral setal brush.

Abdominal segments with well-defined median gap in each row of tergal setae. Tergal setae (postspiracular setae and short associated setae on tergites II–VIII are not included): I, 4–6; II, 7–10; III, 6–10; IV, 8–10; V, 7–9; VI, 6–8; VII, 4–6; VIII, 4–5. Postspiracular setae very long on tergites II, IV and VIII (0.29–0.36); long on I and VII (0.17–0.23); and short on III, V and VI (0.10–0.17). Length of inner posterior seta of last tergum, 0.06–0.08; short lateral marginal seta of last segment, 0.02. Pleural setae: I, 3–4; II, 4–5; III, 4–5; IV, 4–5; V, 3–5; VI, 3–4; VII, 3; VIII, 3 (2 in one case on one side). Pleurites with only short spine-like setae; pleurites with slender and longer setae: IV, 1–3; V, 1; VI, 1; VII, 1; pleurites without anterior setae. Pleurite VIII with inner setae (0.04–0.06) twice as long as outer (0.02–0.03). Anterior margin of sternal plate II without a medial notch. Sternal setae: I, 0; II, 3–4 in each aster, aster setae length: s1, 0.03–0.06; s2, 0.02–0.05; s3, 0.02–0.04; s4, 0.01–0.03; with 8–14 marginal setae between asters, 4–7 medioanterior; III, 12–19; IV, 14–28; V, 21–24; VI, 19–24; VII, 11–15; VIII, 9–10; remainder of plate, 6; and with 3 setae posteriorly; sternites III–VII with medioanterior setae: IV, 2; V, 2–3; VI, 1; VII, 1–3. With 8 internal anal setae. Genital sac sclerite as in Figs 3–4 , quite large with broadly rounded distal margin and densely fringed patches on the lateral sides. The medio-distal part of the sclerite is less sclerotized, forming a central pale area. The outline of the proximal margin of the plate is indistinguishable.

Dimensions ex A. caudatus : TW, 0.38–0.40; POW, 0.30–0.32; HL, 0.24–0.26; PW, 0.24–0.27; MW, 0.31–0.36; AWIV, 0.42–0.52; GW, 0.10–0.13; GL, 0.35–0.40; ParL, 0.07–0.09; GSL, 0.08–0.11; TL, 1.07–1.28. Dimensions ex A. concinnus : TW, 0.35; POW, 0.28; HL, 0.23; PW, 0.22; MW, 0.30; AWIV, 0.42; GW, 0.10; GL, 0.34; ParL, 0.08; GSL, 0.10; TL, 1.18.

Material examined

Ex Aegithalos caudatus alpinus (Hablizl, 1783) —Northern long-tailed tit.

Lectotype ♀ designated below: AZERBAIJAN, Alexejevka , Lankaran Region, 10 Mar. 1934, I.S. Shtrom ( ZISP 364 ) . Paralectotypes: AZERBAIJAN, 3♀♀, 3♂♂, same locality as lectotype, 23 Feb. 1934, I.S. Shtrom leg. ( ZISP 212–214 ) ; 4♀♀, 2♂♂, Kumbashi, Lankaran Region, 9–10 Mar. 1934 ( ZISP Nos 332, 358, 363, 364) .

Non-types

Ex Aegithalos caudatus ( Linnaeus, 1758) —Long-tailed tit

RUSSIA: 2♀♀, 2♂♂, unknown locality , 21 Jun. 1940 ( ZISP 7 a), identified by Blagoveshtchensky .

Ex Aegithalos caudatus cf. caudatus ( Linnaeus, 1758) —Long-tailed tit

RUSSIA: 1♀, Krasnojarskiy kr., Usinskiy tr. st., Kulumys, 12 Jun. 1940 ( ZISP 43 ), identified by Blagoveshtchensky .

Ex Aegithalos caudatus europaeus (Hermann, 1804) —European long-tailed tit

CZECH REPUBLIC: 2♀♀, 2♂♂, Břeclav-Kančí obora, 24 Feb. 1954 ( MMBC 689 ) ; 1♀, Břeclav-Kančí obora, 25 Feb. 1954, identified by Balát ( MMBC 680 ) .

Ex Aegithalos concinnus annamensis (Robinson & Kloss, 1919) —Black-throated bushtit

VIETNAM: 2♀♀, 1♂, NP Bidoup-Nui Ba , 11 Sep. 2012, VETUNI (LB074, LB076, LB077) ; 2♀♀, NP Bidoup-Nui Ba , 14 Sep. 2012 ( VETUNI LB139 ) .

Designation of Lectotype

Considering the incomplete original description of Myrsidea aegithali , the several syntypes available in the Blagoveshtchensky’s Collection, and the new host records for this louse species, we believe it is advisable to designate a syntype female as the lectotype. Therefore, here we designate the best preserved syntype female as the lectotype of Myrsidea aegithali , with data as given above and deposited in ZISP (364, Fig. 20 ).

Remarks

Myrsidea aegithali is the only known species of Myrsidea from members of the family Aegithalidae (see Kolencik et al. 2024: 38). The original Russian description includes scarce data, without setal counts and lacking some diagnostic characters used by Clay (1966). There can be no doubt that Aegithalos caudatus alpinus is a regular and natural host of M. aegithali because Blagoveshtchensky (1940) examined specimens from seven different host individuals. We have found two additional samples collected by Blagoveshtchensky but not included in his original description, one of which represents a new host record because, according to the location, it was most likely collected from the nominotypical subspecies Aegithalos caudatus caudatus . Furthermore, we have added two new host records for M. aegithali : the European subspecies of the long-tailed tit, Aegithalos caudatus europaeus , and the black-throated bushtit Aegithalos concinnus annamensis . These new host records also extend the known geographical distribution of M. aegithali from Europe to southeast Asia. Specimens from the black-throated bushtit collected in Vietnam ( Figs 5–6 ) exhibit minor morphological differences, especially smaller dimensions, when compared with the type specimens. However, we believe that these differences fall well within the intraspecific variation of this louse species and may be due to the different sizes of their hosts: mean body length 5.41–5.54 cm (without tail) and weight 7.22–7.39 g for A. caudatus against 4.82–4.96 cm (without tail) and 5.72–5.97 g for A. concinnus (see Li et al. 2010). Also del Hoyo et al. (2008) mentioned weight 6.2–10.4 g and 4–9 g for A. caudatus and A. concinnus , respectively.

This phenomenon, where larger birds harbour larger parasites belonging to the same genus—Harrison’s Rule— has been well documented for lice by Harnos et al. (2017).

Figures

FIGURES 1–4. Myrsidea aegithali (ex Aegithalos caudatus): 1, dorso-ventral views of female thorax and abdomen. 2, female metasternal plate and sternites I–II. 3–4, male genital sac sclerites.

FIGURES 5–6. Myrsidea aegithali (ex Aegithalos concinnus), dorso-ventral views: 5, female. 6, male.

FIGURES 20–24. Myrsidea aegithali, habitus: 20, lectotype female. 21, paralectotype male. 22, lectotype slide (lectotype marked by a black square). 23, female from Aegithalos concinnus. 24, male from Aegithalos concinnus.