Nemastomatidae Simon, 1872
Nemastomatidae represents the most diverse family of the Dyspnoi, contributing more than half the genera and about a third of the species. They are very small to medium sized harvestmen with a disjunct Holarctic distribution. The center of diversity is the Western Palearctic, where most genera and species of the Nemastomatinae occur that often reach high population densities. The subfamily is also present in Asia. The second subfamily, Ortholasmatinae, has the most described species in Central America and along the Western Coast of North America. Two species occur in isolated localities in Asia.
Prominent features of Nemastomatidae are the complex club-shaped hairs on the palps, whose function is still speculative (Wachmann 1970). These hairs can be found in juveniles of other Troguloidea, but in Nemastomatidae they are prominent in all stages of live. The translated scientific name “thread-mouth” likely refers to the palps being covered with these conspicuous hairs (Simon 1872). Other features of the family are unique male genital morphological traits within the Dyspnoi: unlike other Troguloidea, the glans is not movable against the truncus and the slender truncus cane is probably deformed as a whole when the muscles are contracted. The muscles are concentrated in the bulblike base of the penis and muscular tendons connect muscles and the distal part of the truncus (except for Mitostoma). The mechanical stress applied to the distal part of the penis leads to the development of exotic wing like stabilizing structures (Martens 2011, Schönhofer and Martens 2012). Many Nemastomatidae show rich and elaborate ornamentation of the dorsal body, with rows of spines, elevated cones, bridge-thorns and/or triangular intersecting thorns, forming distinct patterns that are species- or even group- specific.
Taxonomy and Discussion of Phylogenetic Relationships
Efforts to organize the diversity within Nemastomatidae started relatively late with Roewer (1951) and Kratochvíl (1958). Since then, taxonomy moved from applying exclusively external morphological characters towards an elaborate systematic interpreting male genital morphological functionalities and male cheliceral apophyses and glands (started by Šilhavý 1966, summarized in Schönhofer and Martens 2012). New genera and species are still described on a regular basis, suggesting research to be necessary in many geographic areas, especially in Asia (Martens 2006, Snegovaya 2010, Schönhofer and Martens 2012) and Central America (Shear 2006, 2010).
References
Kratochvíl, J. 1958. Höhlenweberknechte Bulgariens (Palpatores - Nemastomatidae). Práce Brnenské základny Ceskoslovenské akademie ved 30(12):523-576.
Martens, J. 2006. Weberknechte aus dem Kaukasus (Arachnida, Opiliones, Nemastomatidae), Senckenbergiana biologica 86(2):145-210.
Martens, J. 2011. The Centetostoma scabriculum complex - a group of three cryptic species (Arachnida: Opiliones: Nemastomatidae). Zootaxa 2783:35-51.
Roewer, C. F. 1951. Über Nemastomatiden. Weitere Weberknechte XVI. Senckenbergiana 32:95-153.
Schönhofer, A.L. and J. Martens. 2012. The enigmatic Alpine opilionid Saccarella schilleri gen. n., sp. n. (Arachnida: Nemastomatidae) - isolated systematic placement inferred from comparative genital morphology. Organisms Diversity and Evolution (online).
Shear, W. A. 2006. Martensolasma jocheni, a new genus and species of harvestman from Mexico (Opiliones: Nemastomatidae: Ortholasmatinae). Zootaxa 1325:191-198.
Shear, W. A. 2010. New species and records of ortholasmatine harvestmen from México, Honduras, and the western United States (Opiliones, Nemastomatidae, Ortholasmatinae). ZooKeys, 52:9-45.
Šilhavý, V. 1966. Über die Genitalmorphologie der Nemastomatidae (Arach., Opiliones). Senckenbergiana biologica 47:67-72.
Simon, E. 1872. Notices sur les arachnides cavernicoles et hypogés. Annales de la Société Entomologique de France 5(2):214-244.
Snegovaya, N. Y. 2005. New Harvestman Genus and Species from Kyrgyz Republic (Kyrgyzstan) (Arachnida: Opiliones: Nemastomatidae). Acta Zoologica Bulgarica 62(3):351-354.
Wachmann, E. 1970. Der Feinbau der sog. Kugelhaare der Fadenkanker (Opiliones, Nemastomatidae). Zeitschrift für Zellforschung 103:518-525.
Credits
Page created by Axel L. Schönhofer. Angela DiDomenico helped improve the English
Prominent features of Nemastomatidae are the complex club-shaped hairs on the palps, whose function is still speculative (Wachmann 1970). These hairs can be found in juveniles of other Troguloidea, but in Nemastomatidae they are prominent in all stages of live. The translated scientific name “thread-mouth” likely refers to the palps being covered with these conspicuous hairs (Simon 1872). Other features of the family are unique male genital morphological traits within the Dyspnoi: unlike other Troguloidea, the glans is not movable against the truncus and the slender truncus cane is probably deformed as a whole when the muscles are contracted. The muscles are concentrated in the bulblike base of the penis and muscular tendons connect muscles and the distal part of the truncus (except for Mitostoma). The mechanical stress applied to the distal part of the penis leads to the development of exotic wing like stabilizing structures (Martens 2011, Schönhofer and Martens 2012). Many Nemastomatidae show rich and elaborate ornamentation of the dorsal body, with rows of spines, elevated cones, bridge-thorns and/or triangular intersecting thorns, forming distinct patterns that are species- or even group- specific.
Taxonomy and Discussion of Phylogenetic Relationships
Efforts to organize the diversity within Nemastomatidae started relatively late with Roewer (1951) and Kratochvíl (1958). Since then, taxonomy moved from applying exclusively external morphological characters towards an elaborate systematic interpreting male genital morphological functionalities and male cheliceral apophyses and glands (started by Šilhavý 1966, summarized in Schönhofer and Martens 2012). New genera and species are still described on a regular basis, suggesting research to be necessary in many geographic areas, especially in Asia (Martens 2006, Snegovaya 2010, Schönhofer and Martens 2012) and Central America (Shear 2006, 2010).
References
Kratochvíl, J. 1958. Höhlenweberknechte Bulgariens (Palpatores - Nemastomatidae). Práce Brnenské základny Ceskoslovenské akademie ved 30(12):523-576.
Martens, J. 2006. Weberknechte aus dem Kaukasus (Arachnida, Opiliones, Nemastomatidae), Senckenbergiana biologica 86(2):145-210.
Martens, J. 2011. The Centetostoma scabriculum complex - a group of three cryptic species (Arachnida: Opiliones: Nemastomatidae). Zootaxa 2783:35-51.
Roewer, C. F. 1951. Über Nemastomatiden. Weitere Weberknechte XVI. Senckenbergiana 32:95-153.
Schönhofer, A.L. and J. Martens. 2012. The enigmatic Alpine opilionid Saccarella schilleri gen. n., sp. n. (Arachnida: Nemastomatidae) - isolated systematic placement inferred from comparative genital morphology. Organisms Diversity and Evolution (online).
Shear, W. A. 2006. Martensolasma jocheni, a new genus and species of harvestman from Mexico (Opiliones: Nemastomatidae: Ortholasmatinae). Zootaxa 1325:191-198.
Shear, W. A. 2010. New species and records of ortholasmatine harvestmen from México, Honduras, and the western United States (Opiliones, Nemastomatidae, Ortholasmatinae). ZooKeys, 52:9-45.
Šilhavý, V. 1966. Über die Genitalmorphologie der Nemastomatidae (Arach., Opiliones). Senckenbergiana biologica 47:67-72.
Simon, E. 1872. Notices sur les arachnides cavernicoles et hypogés. Annales de la Société Entomologique de France 5(2):214-244.
Snegovaya, N. Y. 2005. New Harvestman Genus and Species from Kyrgyz Republic (Kyrgyzstan) (Arachnida: Opiliones: Nemastomatidae). Acta Zoologica Bulgarica 62(3):351-354.
Wachmann, E. 1970. Der Feinbau der sog. Kugelhaare der Fadenkanker (Opiliones, Nemastomatidae). Zeitschrift für Zellforschung 103:518-525.
Credits
Page created by Axel L. Schönhofer. Angela DiDomenico helped improve the English
Fig. 1 from Schönhofer and Martens (2012): Systematic framework of Troguloidea depicting development of selected character within the Nemastomatidae. Bold branches and GB (GenBank) following genus names indicate phylogenetic information based on 28S rRNA, dashed branches indicate tentative placement of additional genera upon outlined morphological features. Numbers at nodes indicate posterior probabilities less than 1.00 (according to Schönhofer and Martens 2010). Black arrows special features; red arrows independent evolution of wing-structures as discussed in the text. All drawings on the right show the distal part of the penis cane with glans and stylus; from top to bottom: Carinostoma carinatum (A; ventral, Martens 1978, Fig. 195); Histricostoma caucasicum (A; dorsal, Martens 2006, Fig. 26b); Paranemastoma kochi (A; ventral, Martens 1978, Fig. 169); Vestiferum alatum (B; dorsal, Martens 2006, Fig. 18 k); Mediostoma variabile (B; ventral, Martens 2006, Fig. 25o); Caucnemastoma golovatchi (C; dorsal, Martens 2006, Fig. 19c); Giljarovia trianguloides (C; ventral, Martens 2006, Fig. 7c); Nemaspela femorecurvata (C; ventral, Martens 2006, Fig. 14c); Nemastoma triste (D; dorsal, Martens 2006, Fig. 22d); Hadzinia karamani (E; dorsal, Šilhavý 1966, Fig. 1); Pyza bosnica (F; dorsal, Gruber 1979, Fig. 20); Acromitostoma rhinocerus (G; dorsal, Rambla 1983, Fig. 1f); Centetostoma juberthiei (G; dorsal, Martens 2011, Fig. 32); Nemastomella dubium (H; dorsal, Rambla 1969, Fig. 6); Starengovia kirgizica (I; dorsal, Snegovaya 2010, Fig. 7); Saccarella schilleri (K; dorsal); Mitostoma gracile (L; lateral, Martens 2006, Fig. 35c); Dendrolasma mirabile (M; ventral, Shear and Gruber 1983, Fig. 184); Ortholasma coronadense (M; ventral, Shear and Gruber 1983, Fig. 121). Within the tree (in lower case letters, including those between genera names) from top to bottom: Carinostoma elegans (a; penis ventral, Martens 1978, Fig. 201); Paranemastoma quadripunctatum (b; basal cheliceral segment lateral, Martens 1978, Fig. 156); Paranemastoma kochi (c; penis ventral, Martens 1978, Fig. 169); Vestiferum funebre (d; apophysis medial, Martens 2006, Fig. 18f); Giljarovia vestita (e; chelicera apophysis, medial, Martens 2006, Fig. 9k); Nemastoma triste (f; penis lateral, Martens 1978, Fig. 127); Mitostoma chrysomelas (g; body and legs; Germany, Mainz); Saccarella schilleri (h; chelicerae medial); Centetostoma scabriculum (i; apophysis medial, Martens 2011, Fig. 7); Mitostoma chrysomelas (k; chelicerae lateral, Martens 1978, Fig. 214); Ortholasma coronadense (l; chelicerae lateral, Shear and Gruber 1983, Fig. 102); Ortholasma colossus (m; body; Tulare, Three Rivers, CA); photos by A.S.
