Neotype is

Options

A. Nomenclatural type from original ma- terial
B. Nomenclatural type when original ma- terial is missing
C. One of the two or more specimens cited by author
D. New species discovered by a worker

Answer

### Step-by-Step Solution:

1. **Understanding Neotype**:
- Neotype is a term used in biological nomenclature. It refers to a specimen that is selected to serve as the type when the original type specimen (holotype) is no longer available.

2. **Identifying the Context**:
- In taxonomy, a type specimen is crucial for the identification and classification of species. If the original specimen is lost or cannot be located, a neotype can be designated to maintain the stability of the nomenclature.

3. **Evaluating the Options**:
- **Option A**: Nomenclature type from original material - This is incorrect because a neotype is used when the original material is not available.
- **Option B**: Nomenclature type when original material is missing - This is correct as it directly defines what a neotype is.
- **Option C**: One of the two or more specimens cited by the author - This describes a different concept, not specifically a neotype.
- **Option D**: New species discovered by a worker - This is also incorrect as it does not relate to the definition of a neotype.

4. **Conclusion**:
- Based on the definitions and the evaluation of the options, the correct answer is **Option B**: Neotype is a nomenclature type when original material is missing.