Xantholinus (Meneidophallus) dvoraki Coiffait, 1956

Gusarov, Vladimir I., 2002, Xantholinus dvoraki Coiffait, 1956, the only valid species of the subgenus Meneidophallus Bordoni, 1999, with remarkably variable internal sac of aedeagus (Coleoptera, Staphylinidae), Zootaxa 21, pp. 1-11 : 2-9

Xantholinus (Meneidophallus) dvoraki Coiffait, 1956 ( Figs. 1–7 )

Xantholinus (s.str.) dvoraki Coiffait, 1956a: 163

Xantholinus (s.str.) roubali Coiffait, 1956b: 142 , syn. nov.

Xantholinus (s.str.) dissimilis Coiffait, 1956b: 143 , syn. nov. Xantholinus (s.str.) alaiensis Coiffait, 1966a: 125 , syn. nov.

Xantholinus (s.str.) schweigeri Coiffait, 1966b: 22 , syn. nov. Xantholinus (s.str.) schweigeri Coiffait, 1971: 431

Xantholinus (Meneidophallus) balaton Bordoni, 1973a: 47 , syn. nov. Xantholinus (Meneidophallus) varhegyanus Bordoni, 1973b: 152 , syn. nov. Xantholinus (Meneidophallus) lichtneckerti Tóth, 1985: 173 Xantholinus (Meneidophallus) magyaricus Tóth, 1985: 174 , syn. nov.

Xantholinus (Meneidophallus) pseudobalaton Tóth, 1985: 175 , syn. nov.

Xantholinus dvoraki: Lohse, 1987: 138 .

Xantholinus lichtneckerti: Lohse, 1987: 138 (as synonym of X. dvoraki ).

Xantholinus schweigeri: Lohse, 1987: 138 .

Xantholinus magyaricus: Lohse, 1987: 138 (as synonym of X. schweigeri Coiffait, 1971 )

Xantholinus (Meneidophallus) dvoraki: Gusarov, 1998: 105

Xantholinus schweigeri Coiffait, 1971 : Herman, 2001a: 32 (as synonym of X. schweigeri Coiffait, 1966 )

Type material

Holotype of X. dissimilis , (1Sb(1+1)M), Slovakia: Bystrica (MNHN); holotype of X. roubali , (1Sb(1+1)M), Slovakia: Bratislava (MNHN); holotype of X. varhegyanus , (1Sb1M), Romania: Varhegy (Zoppa) (CB).

Material additional to the above types

Russia: Belgorod reg.: (1Sb1M), Borisovka (D.Krasil’nikov) 16­19.x.1988; (1Sb1M), 2 (1Sb(1+1)M), ditto but 13­16.x.1988; (1Sb1M), (1Sb(1+1)M), ditto but 10­13.x.1988; (2Sb(1+1)M), ditto but (V.A.Krivokhatskiy) 6.iv.1985; Voronezh reg.:

(1Sb(1+1)M), Voronezh (V.Kozlov) 15.v.1960 (all – DESPU); (1Sb(1+1)M), 25km NNE Voronezh, Usmanskiy Bor (M.N.Tsurikov) 2.x.1992; (1Sb(1+1)M), ditto but 23.x.1992 (all – CT); (1Sb(1+1)M), ditto but 21.iii.1995; (2Sb(1+1)M), ditto but 5.iv.1995; Samara reg.: (2Sb(1+1)M), Zhigulyovskiy Nature Reserve (Yu.P.Krasnobayev) 2­17.v.1988; Rostov reg.: (2Sb(1+1)M), Rostov­na­Donu (E.A.Khachikov) v.1992; (1Sb(1+1)M), ditto but 29.viii.1976 (all – DESPU); 2 (2Sb(1+1)M), Kamensk, (E.A.Khachikov) 7.viii.1996 (DESPU, CK); (0Sb1M), 4 (1Sb(1+1)M), (2Sb(1+1)M), Shchepkinskiy Les (E.A.Khachikov) 15.ix.1991 (DESPU, CK); (2Sb(1+1)M), (2Sb1M), ditto but 10.ix.1992 (DESPU); Kabardino­Balkarskaya Aut. Republic: 2 (1Sb(1+1)M), Nal’chik, B.Kizilovka (A.Kravets) 23.v.1987; Turkey: (2Sb(1+2)M) W. Anatolia, Abant Gölü, 1450m (G.Fagel), v.1967; 3 (1Sb2M, 1Sb(1+2)M, 2Sb(1+1)M) W. Anatolia, Abant Dagh, 1400­1550m (G.Fagel), v.1967 (all – IRSNB); Kazakhstan: (1Sb(1+1)M) Dzhambul (ZFMAK).

Diagnosis

Among other species of Xantholinus specimens of X. dvoraki can be easily recognized by the combination of: black head; dark brown pronotum, elytra and abdomen; reddish brown antennae, palpi and legs; head with transverse microsculpture, often erased in the center of the disc; pronotum without microsculpture or with weak transverse microsculpture near lateral margin; aedeagus with 1­5 isolated spines in the middle portion of internal sac ( Figs. 3­7 ).

Discussion

In the subgenus Meneidophallus the internal sac includes the following structures ( Figs. 1­2 ): two apical rows of spines (A1­A2), the median group of isolated spines (M), the subbasal group of isolated spines (Sb), four basal rows of spines (B1­B4) and the basal group of scales (L). Relative position of these structures refers to everted sac. When it is packed inside the aedeagus capsule the apical structures of the sac lie at the bottom of the aedeagus while the basal structures of the sac are located close to the aedeagus apex.

1 – aedeagus, dorsal view; 2 – partially everted internal sac of aedeagus. A1­A2 – two apical rows of spines; B1­B4 – four basal rows of spines; L – basal group of scales; M – median group of isolated spines; Sb – subbasal group of isolated spines. Scale 0.25 mm (1), 0.4 mm (2).

The basal group of scales (L), four basal (B1­B4) and two apical (A1­A2) rows of spines were present in all specimens that I examined. Coiffait (1956b) reported that in the holotype of X. dissimilis the apical rows of spines were entirely missing. However, the reexamination of the holotype demonstrated that both apical rows were in fact present. The genitalia preparation made by Coiffait is very pale, probably because of overexposure to KOH, and apparently Coiffait did not notice the spines of the apical rows.

The median and subbasal groups of isolated spines are subject to variation in Meneidophallus. The number of spines in these groups varies, and the spines within a group may be separate or close to each other ( Figs. 3­7 ). In the latter case a pair of spines is enclosed in the shared pocket which is clearly visible when the sac is not everted ( Figs. 6­7 ). In this paper I will use abbreviations to describe the number of spines in the median (M) and subbasal (Sb) groups. For example, the abbreviation 2Sb(1+1)M means that the sac has two juxtaposed spines (in the shared pocket) in the subbasal group and 2 separate spines in the median group.

It is worth mentioning that the characters of internal sac are often hard to observe and even harder to illustrate when the sac is packed inside the aedeagus capsule. It is easy to miss a spine if it is blocked by other structures. For example, in his description of X. varhegyanus Bordoni (1973b) illustrates and describes the internal sac as 0Sb 1M. However, the reexamination of the holotype demonstrated that the correct formula was 1Sb 1M. Unfortunately, it is impossible to evert the internal sac of the specimens that have been preserved in alcohol or dried. To illustrate the spines of the median and subbasal groups it is more convenient to dissect the aedeagus and remove the internal sac, as has been done by Tóth (1985) and done in this paper ( Figs. 3­7 ).

Traditionally, the specimens with different sets of median and subbasal spines were assigned to separate species. In fact, the number and relative position of these spines were the only reliable characters used to distinguish between the species described in Meneidophallus ( Table 1 ).

Number of spines in the group

Species name Subbasal group of isolated spines (Sb) Median group of isolated spines (M) The examination of available material shows that the specimens with different types of internal sac occur in the same localities and often in the same samples. To illustrate this fact I compiled the data both from published records and the material that I examined ( Table 2 ). Considering that the specimens with different types of internal sac occur in the same localities and do not differ in any other characters, I regard all these specimens as one and the same species with variable internal sac. Below I present the motives for the synonymy of each name in more details.

I did not examine the holotype of X. dvoraki (type locality: felákovice, Czech Republic). According to the drawing by Coiffait (1956a: Fig. III) the holotype has internal sac of (1+1)Sb2M type. The original description of X. dvoraki agrees with the specimens examined by me (including the males from Slovakia) in all characters except the type of internal sac, which I consider to be extremely variable in this species.

The holotype of X. roubali examined by me does not differ externally from other specimens listed in the material and has internal sac of 1Sb(1+1)M type, which was found to co­occur with four other types of internal sac ( Table 2 ).

The holotype of X. dissimilis examined by me has internal sac of 1Sb(1+1)M type, the same as the holotype of X. roubali , and I could see no significant difference between the two in any other character. According to Coiffait (1956b: Fig. 7 ) the apical rows of spines in internal sac of the holotype of X. dissimilis were entirely missing. My reexamination of the holotype demonstrated that both apical rows were in fact present. The genitalia preparation made by Coiffait is very pale, probably because of overexposure to KOH, and apparently Coiffait did not notice the spines of the apical rows.

I did not examine the holotype of X. alaiensis (type locality: Sakh­i­Mardan, Kyrgyzstan), which has internal sac of 0Sb(1+1+2)M type according to the drawings by Coiffait (1966a: Figs. 3­4 ). The original description of X. alaiensis corresponds to the specimens examined by me (including the male from Kazakhstan (1Sb(1+1)M)) in all characters except the type of internal sac which I consider to be extremely variable in Meneidophallus.

I did not see the holotype of X. schweigeri Coiffait, 1966 b or X. schweigeri Coiffait, 1971 [These two names were synonymized by Herman (2001a) and probably have one and the same specimen as the holotype] (type locality: lake Abant, Turkey). According to the drawings (Coiffait 1966b: Fig. 1 ; Coiffait 1971: Fig. 1 , A) both holotypes have internal sac of 1Sb2M type. Both descriptions published by Coiffait agree with the specimens listed in the material, including four males from near the type locality which have four different types of internal sac (1Sb2M is one of them).

I did not examine the holotype of X. balaton (type locality: Zalavár, Hungary) which has internal sac of 1Sb1M type (Bordoni 1973a: Fig. 2 ). The description of X. balaton corresponds to the specimens examined by me (including the males from Slovakia and Romania) in all important characters. Three different types of internal sac were found to co­occur with 1Sb1M type ( Table 2 ).

The holotype of X varhegyanus examined by me has internal sac of 1Sb1M, and not 0Sb1M, as illustrated by Bordoni (1973b: Fig. B). In all important characters the holotype is similar to the specimens listed in the material.

I did not examine the holotype of X. lichtneckerti (type locality: Sukoró, Hungary) which has internal sac of 2Sb(1+1)M type according to the drawing by Tóth (1985: Fig. 1 ). The description of X. lichtneckerti corresponds to the specimens listed in the material (including the males from Slovakia and Romania) in all important characters. Lohse (1987) considered X. lichtneckerti to be synonymous with X. dvoraki . Eight other types of internal sac were found to co­occur with 2Sb(1+1)M type ( Table 2 ).

I did not see the holotype of X. magyaricus (type locality: Sukoró, Hungary, the same as in X. lichtneckerti ), which has internal sac of 2Sb1M type according to Tóth (1985: Fig. 2 ). The description of X. magyaricus agrees with the specimens listed in the material (including the males from Slovakia and Romania) in all important characters. Lohse (1987) considered X. magyaricus to be a synonym of X. schweigeri Coiffait, 1971 . Four different types of internal sac were found to co­occur with 2Sb1M type ( Table 2 ).

I did not examine the holotype of X. pseudobalaton (type locality: Siófok, Hungary) which has internal sac of 0Sb(1+1)M type (Tóth, 1985: Fig. 3 ). The description of X. pseudobalaton fits the specimens examined by me (including the males from Slovakia and Romania).

Because the number of spines in the internal sac is the only major difference between the forms originally described as separate species of the subgenus Meneidophallus, I consider all these forms to be conspecific and place them in synonymy with X. dvoraki . I could not see any significant difference between the specimens from Central Europe, Turkey and Central Asia.

X. dvoraki is a widespread Western­Central Palaearctic species. The information on its distribution in the Eastern part of the range is fragmentary because the males of X. dvoraki seem to be active in spring and autumn, and rare in summer time, when most collections are made. It is not clear if the females of X. dvoraki are present through the summer, because it is hard to distinguish the females of X. dvoraki from the females of other widespread and common species, such as X. linearis (Olivier, 1795) and X. longiventris Heer, 1839 . Special efforts to collect early and late in the season are needed to clarify the geographical distribution of X. dvoraki .

The possibility of variation in internal sac of Xantholinus has already been mentioned by Lohse (1987) who saw some specimens of X. linearis with one of the normal two big spines missing. Lohse believed that similar variability might occur in Meneidophallus. He assumed that X. dvoraki , X. schweigeri and X. pseudobalaton might be the forms of the same species, but he did not make the final decision since he did not have enough specimens available. I am not aware of any special study of the variability of internal sac in staphylinids, but such work has been done on some species of carabid genera Harpalus Latreille, 1802 and Ophonus Dejean, 1821 (Kataev 1995) . The variation in internal sac of X. linearis and carabids differs from variation in X. dvoraki in one important respect. In the first two the abnormal forms are relatively rare (their frequency is about 2­6% in the five species of carabids studied by Kataev), while in X. dvoraki it is not even possible to tell what is normal ( Fig. 8 ). The frequencies of the two most common forms are 49% and 26%. This is a very unusual example of high intraspecific variability of the internal sac. It seems reasonable to assume that in X. dvoraki the middle portion of the sac is not as important in copulation and is not controlled by selection pressure as tightly as the apical and basal portions.

Figures

FIGURE 8. Frequency distribution of different types of internal sac in examined material.

FIGURES 1 ­ 2. Xantholinus dvoraki Coiffait (1 – Turkey, Abant Dagh; 2 – Russia, Rostov­na­ Donu).

FIGURES 3 ­ 7. Internal sac of aedeagus of Xantholinus dvoraki Coiffait (3, 5, 6 – Russia, Borisovka; 4, 7 – Russia, Rostov­na­Donu). Scale 0.4 mm.

Tables

TABLE 1. Different types of internal sac traditionally assigned to separate species in the subgenus Meneidophallus.

X. pseudobalaton	0	1+1
X. alaiensis	0	1+1+2
X. balaton	1	1
X. varhegyanus	1	1
X. roubali	1	1+1
X. dissimilis	1	1+1
X. schweigeri	1	2
X. dvoraki	1+1	2
X. magyaricus	2	1
X. lichtneckerti	2	1+1

TABLE 2. Co­occurrence of different types of internal sac in the same locality (++, examined material; +, published data).

	A	B	C	D	E	F	G	H	I	J
A 0Sb1M	­­			++				++	++
B 0Sb(1+1)M X. pseudobalaton		­­							+
C 1Sb1M X. balaton X. varhegyanus			­­	++			+		++
D 1Sb(1+1)M X. roubali X. dissimilis	++		++	­­				++	++
E 1Sb2M X. schweigeri					­­	++		+	++	++
F 1Sb(1+2)M					++	­­			++	++
G (1+1)Sb2M X. dvoraki			+				­­
H 2Sb1M X. magyaricus	++			++	+			­­	++
I 2 Sb(1+1)M X. lichtneckerti	++	+	++	++	++	++		++	­­	++
J 2Sb(1+2)M					++	++			++	­­