Amerus cuspidatus, AVANZATI & SALOMONE & BARATTI & BERNINI, 2003

AVANZATI, A. M., SALOMONE, N., BARATTI, M. & BERNINI, F., 2003, Taxonomic revision of Amerus troisi (Berlese, 1883) (Acari, Oribatida, Ameridae) using morphological and biochemical characters, Journal of Natural History 37 (7), pp. 797-819 : 808-813

Amerus cuspidatus n. sp.

Damaeus troisii: Michael, 1890: 417 .

Amerus troisi (partim): Berlese, 1914: 131.

Amerus troisii: Pérez-Iñigo, 1976: 86–90 .

Diagnosis

Ameridae . Rostrum tripartite with an additional sagittal pointed cusp. Exobothridial, rostral and lamellar setae of equal length. Interlamellar setae are short and never touch each other. Bothridial border abaxially indented. Humeral foramen generally shallower and smaller than in A. troisi . Ten pairs of notogastral setae of varying length: the marginal setae p –p are shortest (but longer than in

1 3 troisi ), setae te, ti, ms, r and r are longest.

3 1

Description

The new species is compared to A. troisi : only differences are remarked and illustrated. The new species is also found in the Berlese collection housed in Florence (ISZA). Nevertheless, we have used new material from Farma Valley (SI) to describe the new taxon.

Measurements. The mean size of 10 randomly selected specimens are 1013 m m× 574 m m. The male selected as holotypus is 980 m m× 570 m m.

According to these measurements, A. cuspidatus is larger than both A. troisi and the populations of A. cuspidatus from the Canary Islands.

Colour, cerotegument and cuticle. The only difference in character states seems to be the amount of cerotegument, more dense in A. cuspidatus (figure 3d) and the presence of a punctated microsculpture in the fourth epimeral furrow (figure 2g) and on the humeral surface (figure 3h).

Prodorsum. The most evident diagnostic character of this new species is the peculiar morphology of the rostrum. Its basic structure is similar to that of A. troisi , with two deep incisions forming three cusps, but a pointed tooth surmounts the medial, downward curved cusp (figures 3b, 4a). This feature is so peculiar that no authors, including the good redescription of Amerus troisi from Tenerife by Pérez-Iñigo (1976), have observed it previously: when viewed dorsally, the medial depressed cusp was confused with the long, desclerotized ventral infracapitulum (figure 2f).

All prodorsal setae are similar except for the interlamellar ones: the latter are very short, smooth and slender (figure 5c). Antiaxially, the border of the bothridium is deeply indented; from a dorsal view there are two clear ridges (figure 3c, g).

Lateral characters and notogaster. The humeral foramina seem shallower and the microsculpture is more marked (figure 3e). The notogastral setae are similar to those of A. troisi , but setae r and the p -series are generally longer in the new species 3

(figure 3a, i). Latero-abdominal gland opening is evident (figure 3f).

Ventral characters. It is hard to discern differences; only the g and g genital 5 6

setae and the epimeral setae 4a are generally longer than those of A. troisi (figure 2e). The surface depression at the level of the insertion of pedotectum I is deeper than in A. troisi (figure 2e).

Gnathosoma and legs. There are no differences.

Immatures. Unknown.

Variations. These are related to the dimensions (see above) and all the stated diagnostic characters. We have studied the variability of the most significant diagnostic character: the rostral morphology. The rostral outline of selected specimens from the type population is illustrated dorsally and laterally (figure 5a). The basic morphology is constant, but the medial tooth differs in prominence and sharpness.

Material examined

When not otherwise indicated, the samples were collected by F. Bernini.

Italy: Carpineta, Farma Valley ( SI), Southern Tuscany, U. T.M. 32TPN8372: humus near the river, 250 m, 27 February 1979 (33) (Coll. G. Callaini); locus typicus; Monte di Portofino ( GE), U. T.M. 32TNQ1508: forest humus, 20 May 1974 (2) (Coll. G. Gardini); ibidem: 1 September 1976 (19) (Coll. S. Zoia); ibidem: 6 June 1977 (16) (Coll. R. Poggi); Traso, Bargagli ( GE), U. T.M. 32TNQ0522: forest humus, 22 October 1978 (9) (Coll. R. Poggi); S. Stefano d’Aveto ( GE), M. Groppetto, eastern Ligurian Apennines, U. T.M. 32TNQ3633: forest humus, 1300 m, 1 October 1978 (9) (Coll. S. Zoia); Zumaglia ( VC), Piedmont, U. T.M. 32TMR2949: forest humus, 600 m, 17 August 1979 (1) (Coll. R. Poggi); Poiano ( RE), Reggian Apennines, U. T.M. 32TPR1618: forest humus, 400 m, 13 March 1984 (1) (Coll. G. Manicardi); Mt Freddone, Apuan Alps. U. T.M. 32SPP0378: humus under Fagus sylvatica and Castanea sativa , 850 m, 29 October 1969 (11) (Coll. R. Dallai); ibidem: U. T.M. 32SPP0378: humus under Castanea sativa near stream, 830 m, 29 October 1969 (1) (Coll. R. Dallai); ibidem: humus under C. sativa , 850 m, 29 October 1969 (4) (Coll. R. Dallai); ibidem: idem, 870 m, 29 October 1969 (4) (Coll. R. Dallai); Mt Altissimo, Apuan Alps, U. T.M. 32SNP9878: humus under Fagus sylvatica wood, 1000 m, 12 June 1984 (16); ibidem: idem, 1120 m, 14 April 1997 (1); Mt Forato, Apuan Alps, U. T.M. 32SPP0774: moss on ground and rock, 400 m, 16 June 1970 (3); Camaldoli ( AR), Tuscan Apennines, U. T.M. 32TQP2854: moss and humus under fir trees, 900 m, 5 August 1972 (4) (Coll. R. Dallai); Badia Prataglia ( AR), Tuscan Apennines, U. T.M. 32TQP3253: humus under Fagus sylvatica wood, 1100 m, 5 August 1972 (3) (Coll. R. Dallai); Vallombrosa, Tuscan Apennines, U. T.M. 32TQP0545: humus under Fagus sylvatica wood, 950 m, 21 October 1964 (12) (Coll. J. Travé), kept in Travé Collection, Banyuls-sur-Mer; Farma Valley, Carpineta ( SI), U. T.M. 32TPN8372: humus under Quercus ilex , 250 m, 15 January 1972 (6); ibidem: idem, 250 m, 27 February 1979 (27) (Coll. G. Callaini); ibidem: idem, 250 m, 13 April 1981 (6); ibidem: Bosco della Bandita ( GR), U. T.M. 32TPN8372: humus under Taxus baccata , 25 September 1977 (28) (Coll. G. Callaini); ibidem: humus under Taxus baccata , Fagus sylvatica , Quercus ilex and Castanea sativa wood, 3 October 1977 (38) (Coll. G. Callaini); ibidem: humus under Castanea sativa , 27 February 1979 (1); ibidem: humus under almer wood near Troscia pond, 20 March 1986 (12); ibidem: humus under Taxus baccata and Fagus sylvatica near Troscia pond, 23 March 1986 (1); ibidem: Il Belagaio ( GR), U. T.M. 32TPN8073: humus under Fagus sylvatica , 250 m, 14 December 1979 (51); ibidem: humus under Fagus sylvatica , Castanea sativa , Juniperus and ferns, 6 February 1985 (16); ibidem: humus under Fagus sylvatica and Castanea sativa , 6 February 1985 (1); ibidem: humus and litter in mixed wood of Fagus sylvatica , Quercus cerris and Castanea sativa beside river, 21 April 1988 (15); Puzzolaia del Palazzo, Pietri Neri ( SI), Mt Zoccolino slopes, U. T.M. 32TQN1858: humus under Alnus ornus , 650 m, 24 August 1976 (2); ibidem: forest humus, 650 m, 8 November 1981 (5); Mt Zoccolino, Amiata Massif ( SI), U. T.M. 32TQN1856: humus under Fagus sylvatica and Corylus avellana , 900 m, 5 February 1984 (10); ibidem: idem, 5 May 1984 (5); Pian di Stura, Reatini Mountains ( RI), U. T.M. 33TUH21: humus under Fagus sylvatica wood, 1300 m, 3 August 1967 (4) (Coll. R. Dallai); ibidem: 6 August 1969 (1); Parco degli Astroni, near Naples ( NA), U. T.M. 33TVF2922: humus inside of a trunk, 75 m, 16 February 1972 (9); Galdo ( SA), U. T.M. 33TWE2989: humus under Castanea sativa wood, 380 m, 4 July 1970 (9) (Coll. M. T. Di Gasero); Bosco di Rifreddo ( PZ) (Basilicata), U. T.M. 33TWF7091: humus under Fagus sylvatica, 1200 m , 22 May 1984 (64); Mt Dragone slopes, Pollino massif, U. T.M. 33SWE9617: humus under Fagus sylvatica wood, 1300 m, 14 October 1976 (14); ibidem: humus under Pteridium aquilinum and grasses, 1300 m, 14 October 1976 (4); Il Fortino, Pollino Massif, U. T.M. 33SWE9412: humus and moss under Fagus sylvatica wood, 1500 m, 12 October 1977 (37); Pantano degli Abruzzi, Sila Massif, U. T.M. 33SXD2829: humus under Fagus sylvatica wood, 1250 m, 28 March 1972 (1); Falconara Albanese, Catena Costiera, U. T.M. 33SWD9549: humus, 12 October 1976 (2) (Coll. A. Di Penna); Sardinia, Iglesiente (southwestern Sardinia), is Seddas, U. T.M. 32SNJ2675: humus under Quercus ilex , 1 May 1975 (6) (Coll. E. Malatesta); ibidem: Sa Duchessa, U. T.M. 32SMJ6658: idem, 300 m, 21 March 1976 (1) (Coll. R. Dallai); ibidem: Colle della Campanasissa, U. T.M. 32SMJ83: humus under Quercus ilex and Arbutus unedo , 250 m; 22 March 1976 (1) (Coll. R. Dallai); ibidem: humus under Arbutus unedo , 22 March 1976 (2) (Coll. R. Dallai); ibidem: near Perdaxius, U. T.M. 32SMJ63: humus under Pistacia lentiscus , 100 m, 22 March 1976 (26) (Coll. R. Dallai); ibidem: near Is Carillus, U. T.M. 32SMJ71: humus and moss under Pistacia lentiscus , 280 m, 23 March 1976 (8) (Coll. R. Dallai); ibidem: Domus de Maria to Teulada, U. T.M. 32SMJ81: humus and moss under Mediterranean maquis, 50 m, 24 March 1976 (1) (Coll. R. Dallai); ibidem: Rio Mt Nieddu, Sarroch, U. T.M. 32SNJ02: moss and humus under Quercus ilex , 150 m, 24 March 1976 (57) (Coll. R. Dallai); ibidem: along the road between Is Palaceris and Is Cannoneris, U. T.M. 32SMJ90: humus under Quercus ilex , 565 m, 24 March 1976 (3) (Coll. R. Dallai); Sicily island, Nebrodi Mountains, Cesarò ( ME), U. T.M. 33SVB6994: humus under Quercus cerris, 1050 m , 25 March 1972 (3); ibidem: humus under Fagus sylvatica, 1200 m , 25 March 1972 (12); ibidem: S. Fratello ( ME), humus under Quercus sp. , 800 m, 25 March 1972 (1); ibidem: M.te Pagano, Valle del Caronia, U. T.M. 33SVC5005: humus under Quercus suber , 300 m, 14 May 1991 (2) (Coll. M. Migliorini and M. Baratti); ibidem: U. T.M. 33SVC5003: humus under Quercus gussonei and Q. suber , 580 m, 14 May 1991 (9) (Coll. M. Migliorini and M. Baratti); ibidem: Peloritani Mountains, Monforte S. Giorgio ( ME), U. T.M. 33 SWC 3323: moss and humus in a Quercus wood, 300 m, 25 March 1972 (2); Ibidem: Malabotta Forest, U. T.M. 33SVC0401: humus under Fagus sylvatica, 1250 m , 26 October 1981 (35) (Coll. R. Arcidiacono); ibidem: humus under Quercus cerris, 1185 m , 26 October 1981 (1) (Coll. R. Arcidiacono); ibidem: humus under Quercus cerris and Fagus sylvatica, 1215 m (1) (Coll. M. Migliorini and M. Baratti); ibidem: Etna volcano slopes ( CT): humus under Fagus sylvatica, 1500 m , 12 September 1972 (30) (Coll. R. Arcidiacono); ibidem: along the coastal road near Gioiosa Marea ( ME), U. T.M. 33SVC9025: humus under meadows and Mediterranean maquis, 25 March 1972 (3); ibidem: along the coastal road near Tindari ( ME), U. T.M. 33 SWC 0522: moss on the ground, 25 March 1972 (2); Aeolian archipelago, Salina island, Malfa ( ME), U. T.M. 33SVC8570: humus under Castanea sativa , 120 m, 24 April 1970 (26); ibidem: moss on the ground in garigue near a canyon, 80 m, 24 April 1970 (3); ibidem: moss on the ground in meadows, 90 m, 24 April 1970 (2).

Portugal: Madeira island: on trunks, 3–12 August 1956 (3) (Coll. J. Travé), kept in Travé Collection, Banyuls-sur-Mer .

Spain: Goernika, Pais Vasco: humus under Quercus and Castanea , 18 October 1994 (2) (Coll. N. Salomone); Ceida, Pais Vasco: humus under Quercus sp. , 18 October 1994 (21) (Coll. N. Salomone); Canary Islands, Tenerife, El Bailadero, U. T.M. 28 RCS 8258: humus and litter under Laurisilva, 1 September 1961 (3) (Coll. D. Selga); ibidem: Taganana, U. T.M. 28 RCS 8058: moss, 1 September 1961 (2) (Coll. D. Selga); ibidem: Monte del Agua, cumbre de Erjos, U. T.M. 28 RCS 2134: humus and litter under Laurisilva, 9 September 1961 (1) (Coll. D. Selga); ibidem: Vueltas de Taganana, U. T.M. 28 RCS 8058: 15 March 1973 (1) (Coll. A. Machado); ibidem: M.ta de Totavista, Ruigomez: humus under Laurisilva, 880 m, 21 March 1991 (34) (Coll. G. Sabella); ibidem, Montes de la Mercedes: humus under Laurisilva, 700 m, 10 March 1992 (7) (Coll. A. M. Avanzati and M. Migliorini); ibidem: Macizo de l’Anaga, Afur: humus under Laurisilva, 700 m, 10 March 1992 (13) (Coll. A. M. Avanzati and M. Migliorini); ibidem: Macizo de l’Anaga, El Bailadero, U. T.M. 28 CS 134: moss and humus in Laurisilva, 700 m, 10 March 1992 (40) (Coll. A. M. Avanzati and M. Migliorini); Canary Islands, Gran Canaria, Barranco de los Tilos, Moya: humus under Laurisilva, 700(m, 19 March 1991 (23) (Coll. G. Sabella); Canary Islands, La Gomera, M.te del Cedro, Barranco del Cedro: humus in Laurisilva, 800 m, 19 March 1991 (9) (Coll. G. Sabella); ibidem, Parco Garajonay: moss on the ground and on trunks, 1200 m, 7 March 1992 (10) (Coll. A. M. Avanzati and M. Migliorini); ibidem: humus under Laurisilva forest, 1000 m, 7 March 1992 (21) (Coll. A. M. Avanzati and M. Migliorini); ibidem: Cerro de Araña, U. T.M. 28 RCS 7616: humus under Laurisilva, 1100 m, 2 April 1997 (7) (Coll. N. Salomone); ibidem: Aparta-Caminos, near the boundary of the Parque Nacional de Garajonay, U. T.M. 28 RCS 7516: humus under Laurisilva, 1000 m, 2 April 1997 (3) (Coll. N. Salomone); ibidem: La Laguna Grande, U. T.M. 28 RCS 7913: humus under Laurisilva, 800 m, 2 April 1997 (2) (Coll. N. Salomone); ibidem: Camino per El Cedro, U. T.M. 28 RCS 8213: humus under Laurisilva, 800 m, 3 April 1997 (3) (Coll. N. Salomone).

Morocco: near Ketama, Rif: humus under Quercus ilex in Cedrus atlantica wood, 1550 m, 22 April 1986 (5).

Algeria: Blidah, Algeria, 4/89, specimen kept in Michael’s Collection (British Museum of Natural History, London) and labelled Damaeus troisii Berl. , 1930.8.25.925. (figure 4a); Aokas, Great Kabylia: humus and moss under Eucalyptus sp. and Pinus alepensis near the beach, 2 May 1983 (26); Forêt d’Akfadou, Great Kabylia: humus under Quercus mirbeckii, 1230 m , 3 May 1983 (70); ibidem: humus under Q. mirbecki and Taxus baccata, 1230 m , 3 May 1983 (2); ibidem: moss and humus under Pteridium sp. alongside the stream, 1230 m, 3 May 1983 (3); Forêt du Col de Taimez: humus under Quercus , 3 May 1983 (39); near Tala Guilef, Massif du Djurdjura, Great Kabylia: humus under Quercus ilex and Citisus sp., 1200 m, 9 May 1983 (12); Forêt de Mizrana: humus under Quercus suber , Q. afares and Mediterranean maquis, 740 m, 10 May 1983 (60); Fontaine de Singes, Great Kabylia: humus under Quercus mirbeckii and Q. suber , 695 m, 11 May 1983 (2); near Seraidi, Massif de l’Edough: humus under Quercus suber and Mediterranean maquis, 625 m, 23 October 1984 (5); ibidem: humus inside of a stump, 23 October 1984 (23); Aokas, Great Kabylia: humus under Eucalyptus sp. and Pinus alepensis , 26 October 1984 (5); Forêt d’Akfadou, Great Kabylia: humus under Quercus mirbeckii, 1250 m , 26 October 1984 (13); ibidem: humus and moss in meadow, 1350 m, 27 October 1984 (30); Azeffoun, Great Kabylia: moss and humus under Mediterranean maquis, 10 m, 1 November 1984 (15); Aftis, Lesser Kabylia: moss on ground and rock, 20 m, 4 November 1984 (30); Col du Malab, Lesser Kabylia: humus under Quercus suber and Quercus mirbeckii , 600 m, 6 November 1984 (16); Tamanart, Lesser Kabylia: humus and moss under garigue, 50 m, 8 November 1984 (5).

Tunisia: Ain Drahan: humus under an oak, 700 m, 30 April 1983 (1); ibidem: humus inside of a trunk of Quercus sp. , 700 m, 30 April 1983 (4); ibidem: humus under Quercus suber and Q. mirbeckii , 21 October 1984 (5).

France: Montrejeau , Hautes Pyrénées: without indication of habitat, 6 March 1970 (2) (Coll. A. Valle) .

Greece: Mt Pelion : humus under Fagus sylvatica wood, 15 August 1966 (2) (Coll. Matzakis), kept in Travé’s Collection , Banyuls-sur-Mer; Mt Ossa: humus and litter, about 1000 m, 6 November 1968 (3) (Coll. J. Travé), kept in Travé’s Collection, Banyuls-sur-Mer .

The analysis of material labelled Amerus troisii in the Berlese Collection revealed that some specimens belong to the new taxon: (1) Corfù, Thon! decol. artif. (10/39); (2) Vallombrosa, muschio (147/49, 150/5, 171/17); (3) Boboli, castagno (24/5); (4) Firenze, legno castagno (210/35).

Preparation 171/16 from Vallombrosa contains a dried specimen and its diagnostic characters cannot be detected.

Other specimens, preserved in alcohol vials, have not been examined. They come from the following localities: Vallombrosa (20°/999 and 22°/1095), chestnut-tree wood, Firenze, Cascine (40°/1974) and Populonia (40°/1975).

Geographic distribution and ecology

Amerus cuspidatus is a Mediterranean element widespread in the North ( Italy and Greece) and South ( Tunisia, Algeria and Morocco). It is also present in the Atlantic islands and has colonized the southern mountains (Apennines, Mt Amiata, Pollino, Peloritani Mountains and Sila Massifs). In these countries A. cuspidatus is neither rare nor localized, apart from its ecological preference for forest humus.

In spite of thorough collections by several authors, this taxon is rare and localized in north-eastern Spain (our collection) and French Pyrénées and apparently absent in central Spain (even its presence in southern Spain is dubious, see earlier), Mediterranean France ( Corsica included), most of the islands of the Tuscan Archipelago (except for a few specimens on Elba Island) and most of Sardinia. Collections on the latter island are almost all concentrated in its south-western corner, the Iglesiente.

Amerus troisi and A. cuspidatus cohabitate at many sites along the whole Italian peninsula: in the Ligurian and Tuscan Apennines, the Apuan Alps, Mt Amiata, the Farma Valley ( SI), the Pollino Massif and the Nebrodi Mountains.

Comparative analysis

The diagnostic characters of this new species are as follows: (1) presence of an additional medial tooth in the typical generic rostrum (tripartite); (2) short interlamellar setae; (3) long exobothridial setae; (4) indentation of the antiaxial bothridial border; and (5) very long notogastral setae. Character-states (1), (2) and (4) differentiate A. cuspidatus from A. troisi , while (1) and (5) distinguish the new species from A. polonicus . Finally, the short notogastral setae and the rounded rostrum distinguish A. laticephalus from all the other congeneric species (Mahunka and Mahunka-Papp, 1995).

Do these character-states really distinguish these species or are they only the expression of subspecific differences due to ecologic or geographic factors? In the past, some authors have confused these classical species and/or have identified A. troisi with A. polonicus or A. laticephalus with A. polonicus . New data reveal that specimens of A. troisi and A. cuspidatus largely cohabit, apparently without giving rise to intermediate morphological phenotypes. Is this sufficient evidence? To address this issue and establish the presence of hybrids, we have tested the genetic structure of populations of these two phenotypes ( A. troisi and A. cuspidatus ). The next section describes the results of this study.

To investigate the systematic relationships between A. polonicus and A. laticephalus , we undertook a morphological study; due to the rarity of these species ( A. laticephalus , in particular, may only be a relict or missing entity), biochemical systematics could not be applied.