Goniocotes rectangulatus Nitzsch, 1866

Gustafsson, Daniel R., Grossi, Alexandra A., Ren, Mengjiao & Zou, Fasheng, 2023, The Goniodidae (Phthiraptera: Ischnocera) of peafowl (Aves: Galliformes: Pavo), with description of a new genus, Journal of Natural History 57 (17 - 20), pp. 996-1048 : 1016-1022

Goniocotes rectangulatus Nitzsch [in Giebel], 1866

Goniodes rectangulatus Nitzsch, 1818: 294 nomen nudum.

Goniodes (Philopedon) rectangulus (Nitzsch) ; Stephens 1829: 333 [misprint for rectangulatus ].

Goniocotes rectangulatus Nitzsch [in Giebel], 1866: 389.

Goniocotes rectangulus Giebel, 1874: 185 nomen novum for G. rectangulatus .

( Figures 18–23 )

Type host

Pavo cristatus Linnaeus, 1758 – Indian peafowl.

Type locality

None given; likely Germany.

Description

Both sexes. Head shape as in Figure 12 ; temples not flaring significantly, and without distinct corner at mts1. Marginal carina broad, widening near frons, with irregular inner margin and clear attendant canals to at least some preantennal setae. Preantennal nodi large, connected to marginal carina by narrow neck. Coni broad, blunt, with a tendency in some specimens to curve slightly medianly ( Figure 19 ). Antennae sexually monomorphic. Head chaetotaxy as in Figure 20 ; s 1–6 present in male, but only s1–3 present in female; os sexually monomorphic; mts5 microseta in both sexes. Thoracic segments as in Figures 18–19 . Proepimera fused medianly, mesofurcal pit sublateral. One sternal seta on each side of both meso- and metathorax, no thoracic sternal plates. Pterothoracic setae sparse; lpts and ipts widely separated, smns and mpts absent. Abdominal segments and chaetotaxy as in Figures 18–19 ; tergopleurites sexually dimorphic. Paratergal plates poorly demarcated in both sexes, and illustrated approximately. Sternal plates absent in both sexes. Measurements as in Table 1 .

Male. Tergopleurites II–VIII reduced, widely separated medianly ( Figure 18 ). Abdominal chaetotaxy sparse, without tps or setal rows on all segments. Tergopleurite IX elongated, with median hook-like extension, not overlapping central tergopleurite X. Subgenital plate not clearly demarcated in examined specimen, and not illustrated; presumably similar in shape and size to those of other species in the genus. Male genitalia simple, solenoid, with faint wing-like extensions on distal ends which may be part of genitalia.

Female. Tergopleurites II–VIII elongated ( Figure 19 ). Abdominal chaetotaxy sparse, without tps or setal rows on all segments. Tergopleurites IX–XI fused, proximal margin indented medianly. Subgenital plate poorly sclerotised, seemingly as broad, medianly continuous sclerite at vulval margin ( Figure 22 ). Vulval margin rounded, with chaetotaxy as in Figure 22 . Subvulval plates absent or poorly sclerotised.

Material examined

Non-types (erroneously marked ̍Neoparatypes̾). 1♂, 1♀, Wroclaw Zoo , Poland, 3 May 1975, BM1993-8 , NHMUK010575871–2 ( NHML) .

Remarks

Goniocotes rectangulatus has been reported rarely but regularly over the last 100 years (eg Roman-Bolelli 1947; Rékási 1993), but no description or illustration of this species has been published since von Kéler (1940). As von Kéler (1940) only illustrated the female, it is possible that some published records refer to either of the species of Pavoniocotes described above. As discussed in more detail below, Clay confused G. rectangulatus and G. mayuri , and this confusion may have been more widespread. However, the lack of illustrations or photos in most reports preclude an assessment of whether these reports are correct.

The identity of G. rectangulatus is not straightforward. Nitzsch (1818) and Burmeister (1838) only mentioned the name, without making any attempt to describe it. The first description is therefore in Giebel (1866), who published Nitzsch̾s Latin manuscript; the author is thus Nitzsch. Giebel (1874) published a German description of the species, but the combination of characters given in these two descriptions do not fit well with either Goniocotes found on peafowls or the group here described as Pavoniocotes gen. nov. Nitzsch [in Giebel] (1866) described the temples as ̍[a] ngulis [...] exactis rectis ̾ [= exact right angles], and Giebel (1874) wrote that the temples are ̍rechtwinklig, aber nicht scharf̾ [= right angles, but not sharp]. This fits with males of Pavoniocotes parviceps ( Figure 26 ), but not with G. rectangulatus ( Figure 20 ). However, Giebel (1866) and Giebel (1874) both write that the antennae are sexually monomorphic, which fits with G. rectangulatus ( Figures 18–19 ), but not with P. parviceps ( Figures 26–27 ).

The species illustrated by von Kéler (1940) does not have temples that are ̍exact right angles̾, but only females were in Nitzsch̾s collection at the time Kéler examined it, and Kéler does not comment on the dimorphism of the antennae; however, Kéler̾s placement of this species in ̍ Goniocotinae ̾ implies that the antennae are sexually monomorphic, as this is a character of this subfamily. Conceivably, Nitzsch may have had access to additional specimens, which were lost by the time Kéler examined the collection. Nitzsch̾s collection may even have included some males of P. parvifrons , on which he may have based the description of the temples and, presumably, the name ̍ rectangulatus ̾.

Nevertheless, Kéler̾s description and illustration is based on one of the specimens identified by Nitzsch and Giebel as G. rectangulatus , and this constitutes the only detailed published illustration of this species to date. This is thus presumably the species that has been identified by researchers as G. rectangulatus since at least 1940. Neither Nitzsch, Giebel, nor Kéler designated any holotype or lectotype, but von Kéler (1940) designated ̍2 complete and 1 damaged ♀ ̾ as (syn)types.

Lakshminarayana and Emerson (1971) and Nasser et al. (2015) claimed that the syntypes were lost, and the specimens we have examined are labelled ̍Neoparatypes̾. It is unclear where this designation originated. The collection locality (Wroclaw, Poland), date and host are written in J. Złotorzycka̾s handwriting and style. However, the identification label is from the ZSI, and signed by K.V. Lakshminarayana. The lice were collected in 1975, but integrated into the collection of the NHMUK in 1993, where they are now the only specimens of G. rectangulatus [see Lakshminarayana and Emerson (1971) on the identity of specimens with this name from the Piaget collection]. Notably, neither Złotorzycka̾s collection at MNHW nor the collection at the ZSI contains any neotypes of this species ( Lakshminarayana 1982; Jałoszynski et al. 2014; Sheela et al. 2015), and we have not found any publication in which either Lakshminarayana or Złotorzycka designated neotypes of G. rectangulatus . Moreover, Złotorzycka and Modrzejewska (1988) did not list G. rectangulatus in their catalogue of Polish lice.

Regardless of where this neotype designation was published, it was superfluous. The Halle collection, where most of the specimens examined by Nitzsch and Giebel were stored, was largely destroyed during World War II (eg Clay 1949; Hopkins and Clay 1955; Palma and Pilgrim 1984), but some specimens survived as they were not at the museum during the bombing. This supposedly includes the specimens listed by Clay and Hopkins (1955) as well as those listed by Kéler (1941); the latter list includes three females of G. rectangulatus that Kéler indicate are the types. Dr Hendrik Müller (in litt.) at the ZNS has confirmed that the specimens are still in that collection and provided some photos of the three remaining specimens ( Figure 23 ). These are the same specimens as those examined by von Kéler (1940), and thus constitute the only remaining syntypes of G. rectangulatus . These specimens appear to represent a typical species of Goniocotes , indicating that at least since von Kéler (1940) examined these specimens, there has been no mixture of species in the type series; there is therefore no need to select a lectotype.

Goniocotes rectangulatus is the only member of Goniocotes known from any host in the genus Pavo ( Price et al. 2003) . Two species of Goniocotes s. lat. are known from the Congo peafowl ( Afropavo congensis ), which are the closest relatives of Pavo ( Wang et al. 2014; Chen et al. 2021; Kimball et al. 2021). However, the lice of Congo peafowl are morphologically distinct ( Clay 1938), and likely do not belong in Goniocotes . Given the paucity of verified records of Goniocotes on peafowls, G. rectangulatus may represent a straggler to P. cristatus from an unknown host; among the other species of Goniocotes we have examined (DRG, in prep.), none are particularly close to G. rectangulatus , but most species in the genus have not been re-examined. A general revision of Goniocotes is needed to address this issue.

Figures

Figure 1. Goniodes pavonis (Linnaeus, 1758), male habitus, dorsal and ventral views.

Figure 2. Goniodes pavonis (Linnaeus, 1758), female habitus, dorsal and ventral views.

Figures 3–7. Goniodes pavonis (Linnaeus, 1758). 3, male head, dorsal and ventral views. 4, female antenna and conus, ventral view. 5, male genitalia, dorsal view. 6, male genitalia, ventral view. 7, female genitalia and abdominal segments VII–XI, ventral view.

Figure 18. Goniocotes rectangulatus Nitzsch [in Giebel], 1866, male habitus, dorsal and ventral views. Paratergal plates not clearly demarcated in specimen, and illustrated approximately.

Figure 19. Goniocotes rectangulatus Nitzsch [in Giebel], 1866, female habitus, dorsal and ventral views. Paratergal plates not clearly demarcated in specimen, and illustrated approximately.

Figures 20–22. Goniocotes rectangulatus Nitzsch [in Giebel], 1866. 20, male head, dorsal and ventral views. 21, male genitalia, dorsal view. 22, female genitalia and abdominal segments VIII–XI, ventral view.

Figure 23. Photographs of the remaining specimens (top), the slide labels (middle), and the slide itself (bottom) of Nitzsch̍s Goniocotes rectangulatus Nitzsch [in Giebel], 1866, at the Zentralmagazin Naturwissenschaftlischer Sammlungen, Martin-Luther-Universität, Halle-Wittenberg, provided by Dr Hendrik Müller at the same institute. These specimens constitute the syntype series of G. reticulatus, and are the same as those on which von Kéler (1940) based his illustrations.

Figures 12–16. Goniodes meinertzhageni Clay, 1940. 12, male head, dorsal and ventral views. 13, female antenna and conus, ventral view. 14, male genitalia, dorsal view. 15, male genitalia, ventral view. 16, female genitalia and abdominal segments VII–XI, ventral view.

Figures 26–30. Pavoniocotes parviceps (Piaget, 1880) ex Pavo cristatus Linnaeus, 1758. 26, male head, dorsal and ventral views. 27, female antenna and conus, ventral view. 28, male genitalia, dorsal view. 29, male genitalia, ventral view. 30, female genitalia and abdominal segments VII–XI, ventral view.