Synonymized with P. Maritimus (Leach, 1809); with Notes on Characters for the Separation of This Species from P

Petrobius lohmanderi Agrell, 1944, synonymized with P. maritimus (Leach, 1809); with notes on characters for the separation of this species from P. b revistylis Carpenter, 1913, together with records for both species from Danish coasts (Archaeognatha) LEWIS DA VIES Davies, L.: Petrobius lohmanderi Agrell, 1944, synonymized with P. marltlmus (Leach, 1809); with notes on characters for the separation of this species from P. brevistylis Carpenter, 1913, together with records for both species. from Danish coasts (Archaeognatha). Ent. Meddr 56: 53-60, Copenhagen, Denmark, l988.ISSN 0013-8851. On the basis ofre-examination of the type series, Petrobius lohmanderi Agrell, 1944, is considered to be a junior synonym of P. maritimus (Leach, 1809). Among other features of more limited use, the form of the tip of the ninth coxite on the inner side of the insertion of the style is shown to be reliable in separating this species from P. brevistylis Carpenter, 1913, in both sexes and in juveniles down to about 5 mm body length. Records of the two species show that the latter species is widespread on east coasts of Denmark, while P. maritimus seems rarer. L. Davies, Zoology Department, University of Durham, South Road, Durham DHI 3LE, England. P. lohmanderi Agrell, 1944, a synonym although somewhat decolorized as is normal of P. mcritimus (Leach, 1809) after prolonged storage in alcohol. Agrell gave the type-locality as Faron, Langham Petrobius maritimus (Leach, 1809). mars Hammar, Gotland, listing 4 females as Leach, W.E. 1809, article »Entomology« in the type series, collected 21. vii.l943, from Brewster's Edinburgh Encyclopedia, IX: among loose stones with sparse vegetation 77. on a rocky shore. He also ascribed to the P. Lohmanderi Agrell, 1944. Syn. n. species material from 5 other localities in Agrell, I. 1944. Die schwedischen Thysanu southern Sweden and from Bornholm. ren. Opusc. Ent. 9: 23-36 (description of I have compared the type specimens in P. lohmanderi, pages 31-33). detail with specimens of P. maritimus from British and Danish localities. I can find no differences between P. lohmanderi and P. I have examined the type series of P. loh maritimus. Therefore I consider that manderi from the Natural History Museum, Agrell's taxon is conspecific with P. mariti Goteborg, consisting of three females and mus, so the name P. lohmanderi is a junior one head. The material is in good condition synonym of P. maritimus Leach in my view. Ent. Meddr 56, I -1988 53 ] ..·· 4 5 3 Figs 1-5. Distal abdominal structures in Petrobius maritimus, 1-2 in ventro-lateral, 3-5 in ventral view. la, tip of ninth coxite with style flexed, same specimen as Fig. I. Ninth coxite identified with numeral '9' in each case. Scale lines, approx. 0.75 mm. Approximate body lengths of specimens drawn: Fig. I, fema le, 14 mm; 2, male, 13 mm; 3, female, 11 mm; 4, female, 9 mm; 5, too young to sex, 5 mm. The features of this species that serve to se rable from other Petrobius spp. by two cha parate it from the sole other European Pe racters, first by differing in the relative trobius species that authors consider valid, lengths of certain maxillary palp segments, namely P. brevistylis Carpenter, are discus and secondly by the red colour of the P. loh sed in a later part of this paper. manderi lateral ocelli. Measurements of In the original description of P. lohman lengths of maxillary palp segments in va deri, Agrell stated that the species was sepa- rious specimens from many localities of 54 Ent. Meddr 56, I -1988 [ 6 7 [ 8 9 10 Figs 6-10. Distal abdominal structures in Petrobius brevistylis. Angles of view and other details as for Figs 1-5. Fig. 6, female, 16 mm; 7, male, 13 mm; 8, female, 9 mm; 9, female, 7 mm; 10, not sexable, 5 mm. both Petrobius species show that these di able to enable any reliance to be placed mensions do not provide reliable species upon this feature. separating characters, as indeed was long ago concluded by Womersley (19 30). As to the second character, it is clear to me from Characters for separating P. brevistylis examining many specimens that the colour and P. maritimus of lateral ocelli in these insects is too vari- During the past century and more, some Ent. Meddr 56, I -1988 55 nine species names have been proposed for above male genitalic features. However, the coastal north European Petrobius. On the antenna! character is subject to the limita basis of examination of type or topotypical tion that it cannot be used with very deco material, Womersley (1930) concluded that Iorized specimens after prolonged alcohol there were in reality only two European storage, since the flagellum as a whole be species whose valid names were P. comes pale. The difference between the two maritimus and P. brevistylis. P. /ohmanderi species can still be appreciated in partly was a supposed third species subsequently decolorized specimens if the antennae are recognized, but as stated above this is now viewed at 20-40 X against a white back synonymized with P. maritimus so that the ground. number of valid European species recogni The most widely useful feature for species zed is again reduced to two. separation is undoubtedly the form of the tip Since both species are rather common and of the ninth coxite (foot of Table 1), since it widespread on coasts, provided there are applies to both sexes and all sizes down to 5 rocks above high water mark or where there mm juveniles, and is usable with decolorized are man-made equivalents such as harbour material. This ninth coxite feature was part walls and piers, it seems appropriate to give ly but not clearly specified as such by Car the means for distinguishing the two species, penter (1913) in his text (page 229) giving including a re-discovered distinguishing fea the original description of P. brevistylis, and ture long overlooked, namely the shape of he also partly illustrated it in accompanhing the tip of the ninth coxite. These features figures (Plate 2, Fig. 9 and Plate 3 Fig. IX). are gathered in Table l, illustrated in part in Because Carpenter gave the character in a Figs l-10, and are amplified by the follow rather incomplete way it has been sub ing remarks. sequently overlooked. The male genitalia features separating the two species have been shown in figures in Delany (1954), Mehl (1977), and others. Distribution records for Petrobius spp. Since adult males (that is, those over about 9 mm body length) normally form only a mi in Denmark nority of the total specimens collected, the features are of limited use, particularly since Material of the genus in the Zoological Mu mixed populations of the two species do oc seum of the University of Copenhagen was cur (Davies & Richardson 1970). kindly loaned to me for re-examination. Since in Archaeognatha adults continue This material leads to the locality records as to moult and grow after reaching sexual specified in the two lists of collections given maturity, variation in the length of the aede below for the two Petrobius species now re agus relative to that of the ninth coxite oc cognized. The distribution information so turs. In both species males thus vary in afforded is illustrated by the maps in Fig. body length from 9 to 14 mm, reflecting this 11. continued growth. The shape of the distal Collection information is given in the list part of the aedeagus and the length of its below in the order specified here: name of hairs therefore afford more reliable features locality and sub-locality if available; date of for separating the two species than does the collection as given on the label; name of length of the aedeagus relative to that of the collector if known; and lastly in brackets the ninth coxite. name under which the material was original Because it applies to-both sexes and juve ly determined. Unless otherwise stated each niles down to about 5 mm body length (pro collection was from either stones on beaches bably second or third instars), the antenna! above high water mark, or from harbour flagellum character is more useful than the walls or piers. 56 Ent. Meddr 56, I -1988 Table I. Features distinguishing the two Petrobius species. P. maritimus P. brevistylis (1) Features applying to males only, over (1) Features applying to males only, over about 9 mm body length. about 9 mm body length. Eigth coxite Eigth coxite Not produced into a lobe on the distal edge Produced into a lobe on the distal edge on on median side ofinsertion ofstyle (Fig. 2) medial side ofinsertion ofstyle (Fig. 7). Aedeagus Aedeagus Tip portion shorter, blunt and short-haired, Tip portion longer, more tapering, with lon extending little or not at all beyond end of ger hairs, extending well beyond end ofninth ninth coxite (Fig. 2) coxite (Fig. 7). (2) Features applying to both sexes and juve (2) Features applying to both sexes and juve niles down to 5 mm body length. niles down to 5 mm body length. Antenna! flagellum Antenna/ flagellum Whole flagellum seems to be split into dark Whole flagellum dark, not divided into sec sections, each separated by a single pale tions by single pale joints. joint. Form ofthe tip ofninth coxite. Form ofthe tip ofninth coxite. Distal edge of ninth coxite, on median side Distal edge of ninth coxite, on medial side of of style articulation, prolonged into a sharp style articulation, with shorter and blunter point (Figs 1-5}, such that process so formed process (Figs 6-10), process shorter than dia equals the basal diameter of the style, best meter ofstyle when seen flexed as in Figs 6a, seen when latter is flexed as in Figs la, 2-5.

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