Eodromites aequilatus ( von Meyer, 1857 )

Starzyk, Natalia, 2015, Reappraisal of the primitive crab Eodromites, with description of three new species from European localities (Decapoda: Brachyura: Goniodromitidae), Palaeontologia Electronica 35 (7), pp. 1-19 : 8-11

Eodromites aequilatus ( von Meyer, 1857)

Figures 2, 5

FIGURE 4. Eodromites grandis 1. Groups of hepatic pits (hp) on the hepatic region (3604, Bzów). 2. Rostrum (4874, Niegowonice). 3. Lateral margin covered with serrations (6259, Ogrodzienic). 4. Hepatic tubercles (ht) in the hepatic groove (4244, Ogrodzieniec). 5. Carapace (6259). 6. Mesogastric region, cervical pits (cp), hepatic tubercles (ht) (928, Niegowonice). 7. Lateral view (6255, Niegowonice). 8. Augenrest, anterior view (6259). Scale bars equal 1 mm.

1857 Prosopon aequilatum von Meyer ; von Meyer, p. 556.

1860 Prosopon aequilatum von Meyer ; von Meyer, p. 194, pl. 23, figure 5.

1929 Pithonoton aequilatum (von Meyer) ; Glaessner, p. 318.

1985 Pithonoton aequilatum (von Meyer) ; Collins and Wierzbowski, p. 82, pl. 2, figure 2.

1988 Pithonoton aequilatum (von Meyer) ; Wehner, p. 74, pl. 5, figures 4-5.

2008 Pithonoton aequilatum (von Meyer) ; Schweitzer and Feldmann, p. 130, pl. 3, figures E-F.

2010 Pithonoton aequilatum (von Meyer) ; Schweitzer et al., p. 60.

FIGURE 5. Eodromites aequilatus 1. Rostrum and augenrest, dorsal view, pit (I) on the upper orbital margin (IGPUW C/1/26, Antonie). 2. Serrations on the lateral and upper orbital margin, pit on the upper orbital margin (I), groups of hepatic pits (hp) (SMNS70011/2, Stetten). 3. Groups of hepatic pits (hp) (3558). 4. Carapace (IGPUW C/1/11, Holly Cross Mountains). 5. Mesogastric region, cervical pits (cp), hepatic tubercles (ht), tubercles between cardiac and hepatic groove (hct) (SMNS70011/1, Stetten). 6. Pits on the epibranchial region next to cervical groove (II) and branchio-cardiac groove (III) (IGPUW C/1/27, Zalesiaki). 7. Carapace, groups of hepatic pits (hp) on the hepatic region, pit (I) on the upper orbital margin (3558, Bzów). 8. Augenrest, anterior view (IGPUW C/1/26). 9. Augenrest, anterior view (SMNS70011/2). 10. Lateral view (IGPUW C/1/11). Scale bars equal 1 mm.

2011 Eodromites aequilatus (von Meyer) ; Schweigert and Koppka, p. 11, figure 9.

Diagnosis. Large sized species (length of the carapace up to 16.52 mm), relatively long (length/ width 0.74-0.8). Lateral borders between the outer orbital spine and cervical groove are covered with small spines. Lateral borders behind the cervical groove are smooth. The AtC distance is long (0.42- 0.50 of RtC). Rostrum is short and narrow with a truncated edge. Augenrest is short (length 0.80 of the width), asymmetric along the horizontal axis, with a rounded posterior angle. Upper orbital margin is covered with serrations, the anterior groove is present. Suborbital margin extends beyond upper orbital margin. Projection of orbital margin intercepts longitudinal axis at an angle of ca. 75 degrees. Hepatic tubercles are small. Hepatic pits are arranged in groups. Three pairs of symmetric pits are present: I pair on the upper orbital margin and two pairs on the epibranchial region – II next to cervical groove and III next to the branchio-cardiac groove.

Type material examined. SMNS67336 /1 – neotype , SMNS67336 /2 - topotype - Braunenberg near Aalen-Wasseralfingen (South-West Germany), Upper Oxfordain , Planula Zone, Galar Subzone .

Comparative material. Germany: SMNS 70011/1; SMNS 70011/2 - Stetten near Eybach, Lower Kimmergidian, Divisium Zone.

Poland: MWGUW C/1/11 – Holly Cross Mountains, Oxfordian; MWGUW C/1/026 – Antonie (Wieluń Uppland). MWGUW C/1/027 – Zalesiaki (Cracow Jura Chain), Upper Oxfordian, Planula Zone.

Additional material. Poland, Bzów: I-F / MP /3558/ 1533/08.

Dimensions. Length of the largest specimen (SMNS70011/1) is 16.52 mm. The smallest specimen (IGPUWC/1/27) is 7.73 mm long and 5.92 mm wide.

Description of material. The carapace is convex, relatively long (width 0.74-0.80 of the length) (Figures 2, 5.4, 5.7, 5.10). Lateral margins between the outer orbital spine and cervical groove are covered with small serrations; behind cervical groove the margins are smooth, parallel. The outer orbital spine is distinct and blunt (Figure 5.1). AtC distance is long (0.42-0.50 of the RtC distance) (Figure 3).

The rostrum is short and narrow, with a truncated edge, slightly directed downwards. An axial groove is very deep, reaching the anterior edge of the rostrum (Figure 5.1). The anterior groove is distinct.

The augenrest is short (length 0.8x width), bordered and deep, asymmetric along the horizontal axis, with rounded posterior angle. The upper orbital margin is covered with small spines. The suborbital margin extends beyond the upper orbital margin. The projection of orbital margin intercepts longitudinal axis at an angle of ca. 75 degrees. Details of the augenrest are best visible in specimens SMNS70011/1, SMNS70011/2 and MWGUW C/1/11 (Figures 2.3, 5.8-9).

Hepatic tubercles are faint (Figure 5.5). Groups of hepatic pits are distinct (Figures 2.2, 5.2- 3, 5.7). Three pairs of symmetric pits are present: one pair on the upper orbital margin and two pairs on the epibranchial region – II next to cervical groove and III next to branchio-cardiac groove (Figures 2.2, 5.1-2, 5.6, 5.9). Three small tubercles are present between the cervical and the hepatic groove (Figure 5.5).

Epigastric regions are small, rounded. Mesogastric region is bottle shaped, with distinct borders in the anterior and posterior part, weakly marked in the middle. Two delicate scars occur on both sides of a small incision in the middle of posterior border of the mesogastric region. Anteriorly to them there is a pair of similar, smaller scars (best preserved in specimens SMNS70011/1, SMNS70011/2, SMNS67336/1 and SMNS67336/2; Figures 2.2, 5.5). An easily visible tubercle is present on the urogastric region. Cardiac region is convex, distinct, with two tubercles in the anterior part and one in the posterior part.

The epibranchial region is more convex and much shorter than the branchial region.

The cervical groove is deep; the branchio-cardiac groove is deep in lateral parts (parallel to cervical groove); its middle part is shallower, but also distinctly visible. The postcervical groove is deeper in lateral parts, shallower in the middle and merges with the branchio-cardiac groove.