Ciconiphilus decimfasciatus (Boisduval & Lacordaire, 1835)

Ciconiphilus decimfasciatus (Boisduval & Lacordaire, 1835) View in CoL ( Fig. 1A–H)

Material examined. A total of 140 microscope slides ( 71 females and 69 males) were provided from the collected lice on the great egret Ardea alba . The specimens were collected by Meysam Sharifdini just outside Rasht City ( 37°16′28″N, 49°35′20″E) in September 2023. The lice specimens were identified as Ciconiphilus decimfasciatus (Boisduval & Lacordaire, 1835) ( Phthiraptera : Menoponidae ) based on morphological characters ( Fig. 1). The number of anterior setae (or their alveoli if setae are missing) on abdominal tergites in 20 females of C. decimfasciatus were presented in Table 1 (see Taxonomic note). The lice were collected from different parts of the host body including the neck, wings, back and abdomen. This is the first record of this louse species from the great egret in Iran. No other ectoparasite was observed on the host.

Taxonomic note. Ciconiphilus decimfasciatus is a very similar species to Ciconiphilus butoridiphagus Carriker, 1964 (synonym: C. melanolophi Price & Beer, 1965 ) ( Price & Beer, 1965). They are differentiated using the number of anterior setae on abdominal tergites in females and minor differences in the shape of the penis of the male genitalia ( Price & Beer, 1965). In C. butoridiphagus , the penis is deeply concave in basal margin and with heel-like projection at apical portion, best seen in lateral view, whereas, in C. decimfasciatus , the penis is elongate, slender, with almost straight basal margin and evenly rounded apical bend ( Price & Beer, 1965). The male genitalia of the specimens of this investigation ( Fig. 1H) shows exact similarity with the illustration of C. decimfasciatus provided by Price & Beer (1965) and similar to the photo provided by Amina et al. (2014). The figure of the penis for C. decimfasciatus in Carriker et al. (1964) is slightly different from the figure provided by Price & Beer (1965). Also, Carriker et al. (1964) described C. butoridiphagus based on just female specimens. Price & Beer (1965) described the male and female of C. melanolophi that later became a junior synonym of C. butoridiphagus because they shared the same type-host species ( Price & Emerson, 1966). Except for the figure provided by Price & Beer (1965), there is not any figure or specimen of C. butoridiphagus (or C. melanolophi ) available to the authors to compare the penis shape. Price & Beer (1965), in their key, mentioned that abdominal tergites II– VI have a total of 0–3 anterior setae in C. butoridiphagus and over 3 anterior setae in C. decimfasciatus in females. They added the numbers of anterior setae that were 2–6 on abdominal tergites II–IV, 1–2 on V and 0–2 on VI, and total number of anterior setae on II– VI of 7–18 (average 12.3).

Also, Price & Beer (1965) noted, “Specimens from hosts other than the type-host [ Ardea cinerea ] show occasional departures from the above-cited ranges; however, none of these is consistent enough to enable specific or sub-specific differentiation”. This phenomenon was observed in this investigation, either. The numbers of anterior setae were 2–6 on abdominal tergite II (just one specimen 2, others 3 or more), 3–6 on III, 2–5 on IV ( four specimens 2, others 3 or more), 0–6 ( 13 specimens 0–2 setae, others 3 or more) on V, 0–3 on VI ( 18 specimens 0–2 setae, others 3) and total number of anterior setae on II– VI of 8– 22 (average 14.9) ( Table 1). Kumar et al. (2019) mentioned that the numbers of anterior setae of abdominal tergites are 4 on II, 5 on III, 3 on IV, 3 on V and 2 on VI for each side in a female collected from Bubulcus ibis (cattle egret) in India (Total number = 34). It seems that the numbers are much higher than those of the present study and Price & Beer (1965) ’s work. As the authors know, there is no more data about the chaetotaxy of the species. In this regard, Price & Beer (1965) noted, “Only a study of good series of these closely related species from a number of hosts has enabled us to observe these differences and to verify their stability”. It is noteworthy that Ledger (1980) reported C. decimfasciatus from Butorides striatus from the Transvaal of Africa, whereas Price & Beer (1965) recorded C. butoridiphagus (as C. melanolophi ) from the same host in Cuba and Thailand. Ledger (1980) explained, “It is possible that geographical distribution plays a role in this case, or else the species of lice may sometime prove to be inseparable” and the author did not include C. butoridiphagus in the checklist of Afrotropical Ciconiphilus , even though the host genera Butorides and Ixobrychus were present in the region. Moreover, Zlotorzycka et al. (1999) mentioned the subspecies C. decimfasciatus minor (Piaget, 1885) (synonym: Colpocephalum trchioxum var. minor Piaget, 1885 ) for the species using body measurements, but it is now considered a synonym of C. decimfasciatus ( Price et al., 2003; Smith et al., 2024). It seems that body measurements have not made enough reliable and consistent characters to use in the taxonomy of this species ( Carriker, 1964; Price & Beer, 1965; Zlotorzycka, et al., 1999; Amina et al., 2014; Kumar et al., 2019). It is believed that the body size of lice, and also other parasites, may be influenced by the host body size, the population density of lice, differences in selection pressure exerted by each host, inter and intraspecific competition, microhabitats within the host body, which lice occupy and different community-level interactions ( Johnson et al., 2005; Tryjanowski et al., 2007; Harnos et al., 2017).

Checklist of Phthiraptera of Guilan Province. The checklist of species as well as their hosts, distribution in the province (if it is available) and references, including three suborders, four families, ten genera and 12 species, is presented here. This checklist is regarded as preliminary because few collections and specimens are available for the province.