Morphological variation of Stratiodrilus circensis (Polychaeta, Histriobdellidae) from a new host, Aegla leptodactyla (Crustacea, Anomura, Aeglidae) with identification of its type host species * Author Daudt, Luiz C. C. Author Amato, José F. R. text Zootaxa 2007 1450 57 62 journal article 10.5281/zenodo.176233 c994e6d2-ed8a-4484-9728-f67e184c04d7 1175-5326 176233 Stratiodrilus circensis Steiner & Amaral, 1999 ( Figs. 1–12 ) Description (based on 82 mounted specimens) Male ( n = 28) ( Figs. 1 , 3–4 ): 730–1230 in total body length (892.4; 125.2). Head 100–180 long (143.7; 16.7) with five antennae; median antenna (T1) as long as the first lateral pair (T2), both unsegmented; second lateral pair (T3) bisegmented, twice as long as the length of T2. Three pairs of lateral, unsegmented cirri (C1, C2, C3) a little longer than T2 length, with a pair of posterior cirri (C4) as long as C1-C3 length, with adjacent, conical ventral lobes (Lb), half, shorter or as long as C4; each posterior locomotor appendage with two tubercles (Tu). Posterior locomotor appendages (Pl) 349.6–580 long (450.3; 50.5). Jaw apparatus (Ja) 77.7– 160.9 long (114.1; 22.7) not reaching the limit with the first trunk segment; fulcrum (Fu) 30–100 long (62.2; 19.3). Penis (Pe) 38.8–122.1 long (71.0; 19.2; n = 22). Claspers (Cl) 83.2–88.8 long (86.0; 3.9; n = 2). Female ( n = 25) ( Figs. 2 , 5–6 ): 710.4–1120 in total body length (864.7; 97.2). Head 127.6–180 (142.4; 12.8) long. Birth pores (Bp) immediately behind C3 ( Fig. 2 ). Posterior locomotor appendages 344.1–540 long (443.6; 44.4). Jaw apparatus 77.7–150 long (112.2; 16.7); fulcrum 33.3–100 long (60.3; 16). Number of eggs (Eg) per female, 0–5. FIGURES 1–2. Stratiodrilus circensis . 1. diagram, male in ventral view; 2. diagram, female in ventral view. T1 — median antenna, T2 — first lateral pair of antennae, T3 — second lateral pair of antennae, Ja — jaw apparatus, Ala — anterior locomotor appendages, Fu — fulcrum, C1 - C3 — lateral pairs of cirri, Cl — claspers, Eg — egg, Pe — penis, Bp — birth pores, Pla — posterior locomotor appendages, Tu — tubercles, Lb — conical ventral lobes, C4 — posterior pair of cirri. Scale bars = 300 µm. Host : Aegla leptodactyla Buckup & Rossi, 1977 . Hosts deposited : Coleção de Crustáceos UFRGS Nº 4119 to 4147. The type host specimen as well as two other specimens of A. schmitti , collected from Rio Piraquara, State of Paraná, were deposited in the same collection under Nº 4175. Site of infestation : Branchial chamber. Locality : Rio da Divisa, locality of Silveira, Municipality of São José dos Ausentes, RS, Brazil ( 28º38’17”S , 049º57’46”W ). Prevalence : 70%. Intensity of infestation : 1 to 41 (arithmetic mean 13.3; SD 10.4). Deposited specimens : Ex. A. leptodactyla - adult male CHIOC Nº 36.837 (SBA 1907-2-11 ); adult female CHIOC Nº 36.838 (SBA 1910-2-19 ); juvenile male CHIOC Nº 36.839 (SBA 1907-2-3 ); juvenile female CHIOC Nº 36.840 (SBA 1910-2-5 ); adult male INPA Nº 127 (SBA 1907-2-12 ); adult female INPA Nº 128 (SBA 1907-2-4 ); juvenile male INPA Nº 129 (SBA 1907-2-13 ); juvenile female INPA Nº 130 (SBA 1907-2- 14 ); and juvenile male MZUEC Nº 150 (SBA 1907-2-18 ); adult female MZUEC Nº 151 (SBA 1907-2-1 ); adult male MZUEC Nº 152 (SBA 1907-2-6 ); juvenile female MZUEC Nº 153 (SBA 1910-2-9 ). Ex. A. schmitti - adult male MZUEC Nº 154 (SBA 2084-2-1 ) and adult female MZUEC Nº 155 (SBA 2084-2-3 ). Specimens examined : 11 specimens of S. circensis (mounted in toto ) from Rio Carvalho, collected from the branchial chamber of A. schmitti .